Hi all,

After forced 2 weeks rest, and as ribs are mending, I am back to dealing with the problem of bike refusing to start.

Yesterday I finished putting in the H4 kit from “easterbeaver” and now I have a powerful source of light, stationary... but powerful...

With your permission I want to sum up status with bike and perhaps someone will have some insight how to continue, to ease the discussion I numbered each statement.


1. Bike is a 1987, naked or “base” K100 with about 140K KM.

2. Till this event bike ran very well – only issue was eating a little oil and not so good fuel efficiency – but really ran very well so decided not to play with this and deal with other issues before.

3. Bike has never before failed starting up, I did flood it once, a month before, but after 30 minutes (in summer sun) all was well.

4. Oils and filters less then 1000KM/ 2 months old.

5. Day before failure I had a great 3 hours ride and bike was behaving very well.

6. At end of ride I filled tank completely at a station that is not my usual one (and is only 1.0Km from home).

7. Next day early morning bike would not start.

8. Also would not start downhill – no misfiring – simply nothing.

9. I think a very important indication is the suddenness of the failure, there was no gradual process leading to this.

a. Question: Are there any internal switches that can “kill” / prevent proper start?

10. There is no micro-switch in side stand (regardless I ALWAYS use central stand).

11. IIgnition witch is OK as far as bike electrics are turned on with no issue (lights and indicator lights are strong).

12. When pressing the start button:

a. The starter makes its usual sound (had a friend who is mechanic listen as well.)

b. Question: How can I know if it is turning the engine?

c. Fuel pump can be heard working.

d. After disconnecting fuel line and then pressing the start button, fuel squirts from tube so I ASSUME pump is doing its job?

13. Battery showed 12.4V, connecting my cars battery to bikes battery made no difference.

14. All fuses are intact and correct.

15. Sparks are OK (asked a friend who is experience to have a look as well).

16. Sparkplugs (Bosch x5dc) had some black coating, rather soft.

a. As per HAYNES manual they look something between pictures called “carbon fouling” and “oil fouling”. But spark was good.

b. Regardless, I replaced with new NGK (D7EA) – they too have clear spark.

17. I disconnected, cleaned and reconnected the “ignition control unit” and the “computer” (connections look very good - no free movement)

18. With fuel tank off I pressed start and try very closely to see if any sparks or foul smell come from electric wiring – nothing.

19. I drained fuel completely by siphoning of the tank and then disconnected fuel line and with a few very short presses on start button had it spew out remaining fuel.

20. I replaced fuel with new fuel bought at regular gasoline station and also used to refill car on SAME occasion. Car ran fine (till I wrecked it). I also added some magic potion that is supposed to take water out. I tried again next morning and no difference.

21. There is very little gas smell during all these attempts.

22. Throughout all the attempts there is no misfiring ever, sound is “dry”.

23. Question: How Do I test if fuel is coming out of the injectors – I am hesitant to touch this system – is it possible to take them out one by one and see them spray?

24. Questin: Is it possible that ignition switch will operate lights, starter, sparkplugs and fuel pump but NOT send fuel thru injectors?

25. And finally - what next?


Sorry this is a bit lengthy but perhaps better then a very long back and forth.



I have the HAYNESS and CLYMER manuals but it’s like reading a medicine book – you immediately think you have 90 different diseases.



I really welcome all ideas, it’s all new to me.



Thank you,

Roy

Roy regarding question b. I think even though it may point to a far more serious problem if the engine was not turning it won't hurt to check and at least get that out of the way. One thing immediately comes to mind in that you are getting a spark suggests the hall effect sensor or ignition trigger on the front of the engine is operating and that requires the engine to rotate for that to work. To be certain you could take the cover off and check but I don't think it necessary.

I can't offer anything more than that to go on as you seemed to have covered most bases and I will leave it for those more knowledgeable to assist.

Regards,

Phil

Roys,

Years ago I did have a similar problem and it was a deffective air flow meter.
I also had this type of problem when a squirl decided to use my air filter canister to store his sun flower seeds. Yes, it was close to a pound of seeds inside the canister. The squirl was dropping the seeds from the small air intake in front of the bike .
Have you checked your air filter?
Also check your temperature sensor. It is located in front of the engine below the radiator. The fuel injection computer get signals from the temperature sensor and the air flow meter.

OK,
So Roy has done the good stuff in clearing out the old fuel and even flushing through so that is ok. He has as Phil says verified the engine is turning over because of the stream of sparks, that verifies the engine is turning and the Hall effect sensor is firing. He has also verified the fuel pump runs and fuel pressure is supplied. The strongest clue is the comment by Roy that there is very little gas smell. One would expect to see the plugs wet with fuel after prolonged cranking and one would also smell it coming out of the exhaust as unburnt fuel. Would you try an experiment please Roy. Ignition on, bike in Neutral - warning light showing green all other lights showing on instrument panel. Operate the Kill Switch on the handlebar above the throttle does the condition of the warning lights change in the instrument pod when you switch it on and off, does the fuel pump run every time you return it to the centre position? Having determined that switch off the ignition and report back please. I know how these should perform on my 1990 K100RS 4 Valve but I am not familiar enough with yours to say what they will do on your 1987. I tend not to suspect the fuel because he went from refilling and starting at the gas station then riding home without any problem then the following morning the fault had appeared without any miss firing on the way home which makes me suspect the fuel fill was coincidental not causal.
Regards,
K-BIKE

phil_mars wrote:Roy regarding question b. I think even though it may point to a far more serious problem if the engine was not turning it won't hurt to check and at least get that out of the way. One thing immediately comes to mind in that you are getting a spark suggests the hall effect sensor or ignition trigger on the front of the engine is operating and that requires the engine to rotate for that to work. To be certain you could take the cover off and check but I don't think it necessary.

I can't offer anything more than that to go on as you seemed to have covered most bases and I will leave it for those more knowledgeable to assist.

Regards,

Phil

Hi phil,

I think engine has not seized a (I read that this can actualy happen after engine cools) and bike did role downhill in gear.

still - what can cause a fine running bike to completely fail the next morning?

Roy

Crazy Frog wrote:Roys,

Years ago I did have a similar problem and it was a deffective air flow meter.
I also had this type of problem when a squirl decided to use my air filter canister to store his sun flower seeds. Yes, it was close to a pound of seeds inside the canister. The squirl was dropping the seeds from the small air intake in front of the bike .
Have you checked your air filter?
Also check your temperature sensor. It is located in front of the engine below the radiator. The fuel injection computer get signals from the temperature sensor and the air flow meter.

Following on the well known example of a zoological text with chapter title "snakes of ireland" followed by single sentence "there are no snakes in ireland". There are no squirl in Israel

Perhaps I can do this test - remove airfilter completely for a moment and try starting up? does this make sense - only problem is that I will need to remove fuel tank again.

The tempreture sensor seems well connected - how does one actualy test it , some voltage at rest VS when starting up?

also: how can I test if injectors are passing fuel? Is it allowed to take one injector out and simply look at it while pressing start button?

thank you,
Roy

K-BIKE wrote:OK,
So Roy has done the good stuff in clearing out the old fuel and even flushing through so that is ok. He has as Phil says verified the engine is turning over because of the stream of sparks, that verifies the engine is turning and the Hall effect sensor is firing. He has also verified the fuel pump runs and fuel pressure is supplied. The strongest clue is the comment by Roy that there is very little gas smell. One would expect to see the plugs wet with fuel after prolonged cranking and one would also smell it coming out of the exhaust as unburnt fuel. Would you try an experiment please Roy. Ignition on, bike in Neutral - warning light showing green all other lights showing on instrument panel. Operate the Kill Switch on the handlebar above the throttle does the condition of the warning lights change in the instrument pod when you switch it on and off, does the fuel pump run every time you return it to the centre position? Having determined that switch off the ignition and report back please. I know how these should perform on my 1990 K100RS 4 Valve but I am not familiar enough with yours to say what they will do on your 1987. I tend not to suspect the fuel because he went from refilling and starting at the gas station then riding home without any problem then the following morning the fault had appeared without any miss firing on the way home which makes me suspect the fuel fill was coincidental not causal.
Regards,
K-BIKE

hi,

My ride home is 1 Km and so perhaps the bad fuel did not effect bike yet.

Is it possible that the bad fuel is still in engine?

can i put in engine - thru the spark plugs some VERY strong liquid that will burn for sure ?

tnx
Roy

Roy, I think there was another post about igniting some sort of liquid in the combustion chambers but I don't think it is a job for the faint hearted.

Have you tried starting the bike with the throttle off the stop as mine had a similar fault and I found it only attempted to start with the throttle open a little. It would crank all day with no hint of firing and prior to that had been perfect.

As far as removing the injectors, I have not done it but the instructions in the manual makes it looks quite straight forward and as your bike is not encumbered with a fairing it will make it easier.

They come out as an assembly and you might have enough free play in the cables to at least see if they squirt out. Assuming they are pointed away from the bike

Regards,

Phil

phil_mars wrote:Roy, I think there was another post about igniting some sort of liquid in the combustion chambers but I don't think it is a job for the faint hearted.

Have you tried starting the bike with the throttle off the stop as mine had a similar fault and I found it only attempted to start with the throttle open a little. It would crank all day with no hint of firing and prior to that had been perfect.

As far as removing the injectors, I have not done it but the instructions in the manual makes it looks quite straight forward and as your bike is not encumbered with a fairing it will make it easier.

They come out as an assembly and you might have enough free play in the cables to at least see if they squirt out. Assuming they are pointed away from the bike

Regards,

Phil

After I do some reading.

i will also remove air filter and try.

Will report when done (not much free time these days)

Roy

Everybody has given some good leads to Roy, but his problem is still not solved.
I will try to educate people about the EFI on the Kbikes. I am not an EFI specialist, but here is what I can make of it.
This is a short version of one of the file that you can download (in French).
lets start.........

2 major factors influence the EFI computer: Air flow detected by the air flow meter and engine rpm detected by the HALL sensor
Other data collected by the EFI computer are: Air temperature, Water temperature, Throttle switch position and Battery voltage

Basic:
Fuel pressure is sent from the pump to the Fuel injector ramp. The fuel pressure regulator will keep a constant pressure into the fuel injector ramp. The fuel pressure regulator is located on the back of the fuel injection ramp (not easy to access) and its depression is collected at the intake manifold for cylinder #4.



Air traverses the air filter and goes to the air flow sensor. When you open the throttle, the depression is moving the butterfly and a bigger amount of air is sucked in by the engine.
The idle switch (at the end of the fuel injector ramp) will cut-off the fuel injector when the engine is idling or decelerating. (A good indication of a bad setup is when the engine back fire when decelerating).
When you twist the throttle, the same switch (contact # 2) will tell the EFI computer that the engine is going on full load and the mixture air/fuel will be enriched.



When the engine revs under 900rpm, the EFI computer doesn’t take into account the data collected by the air flow meter. It collects only the air temperature and adjusts the fuel injection accordingly. (The air temperature sensor is a small thermal-resistance located in the air flow meter. Here is a picture of the air temperature sensor:

The EFI computer is pre-programmed to get maximum optimization during startup. As long as the stater switch is depressed, the EFI computer will enrich the mixture air/fuel.
When the engine reaches 900rpm, all data collected by the air flow meter are fed to the EFI computer.

Here are the EFI components: or a full schematic of them:

Here we have the principle of the EFI and related components:

The result is this schematic:

Now, what is interesting is to see the sequence of switches and security affecting the start of the bike (kill switch, starter button, throttle switch, Hall sensors). everything is closely interconnected. As all of us know, when we have an electronic problem, unless you own a BMW circuit analyzer it's like finding a needle in a hay stack...

Before removing the injectors, I would check a couple of things:
Is there any hoses cracked or disconnected? The small vent hose coming from the engine to the air filter (used to recycle oil vapour) is known to crack and this will affect the way that the engine runs as it will unbalance the mixture air/fuel.
Just for the fun, when your bike is iddling open the plug where you refill the oil in the engine. Your bike will start to run like crap. This has the same effect as the vent hose cracked. If you don't see any difference in the way that the bike is running, yes you have an air leak somewhere in your system.
Are the small protecting rubber caps in good shape and not missing (#17 on the next picture)?
Is there enough fuel pressure supplying the fuel injector ramp? (fuel pressure regulator is #2 on the next picture)



Now Roy, you have enough information to keep you puzzled for many days.
By trying to help you, I learned a lot about the EFI. As a result, my previous suggestion that you may have a bad air flow meter seems to be wrong. As I said earlier, the EFI computer doesn't use the data from the airflow meter when the engine is reving under 900rpm. The only think that could be bad would be the thermal resistor. This information is also very important as it rules out a bad water temperature sensor.
Checking your air filter and the electrical connections to the air box could be a good thing.
Don't worry, we will help you to put your bike back on the road.

Years ago, I helped somebody in australia to troubleshout his bike. The fellow had just bought it and it wasn't starting. A the time, we corresponded by Email, I was asking questions and giving leads. The guy was sending me the result of the tests and we continued like this for weeks. I just don't remember who he was and where he was located.

Good luck!

hi,

Thank you for taking the time to write this; I am sure this will benefit mnay people.

It is now early Sat morning and as usual only me and the dogs are up (actually the big one is snoring on the sofa next to me in study). I am reading this with great interest and also the relevant chapters in the manuals.

I hope that over time I too will be able to contribute assistance to others.

Thank you,
Roy

K-BIKE wrote:OK,
So Roy has done the good stuff in clearing out the old fuel and even flushing through so that is ok. He has as Phil says verified the engine is turning over because of the stream of sparks, that verifies the engine is turning and the Hall effect sensor is firing. He has also verified the fuel pump runs and fuel pressure is supplied. The strongest clue is the comment by Roy that there is very little gas smell. One would expect to see the plugs wet with fuel after prolonged cranking and one would also smell it coming out of the exhaust as unburnt fuel. Would you try an experiment please Roy. Ignition on, bike in Neutral - warning light showing green all other lights showing on instrument panel. Operate the Kill Switch on the handlebar above the throttle does the condition of the warning lights change in the instrument pod when you switch it on and off, does the fuel pump run every time you return it to the centre position? Having determined that switch off the ignition and report back please. I know how these should perform on my 1990 K100RS 4 Valve but I am not familiar enough with yours to say what they will do on your 1987. I tend not to suspect the fuel because he went from refilling and starting at the gas station then riding home without any problem then the following morning the fault had appeared without any miss firing on the way home which makes me suspect the fuel fill was coincidental not causal.
Regards,
K-BIKE

The kill switch does indeed kill everything and palying back and forth with it works OK.

The fuel pump can be heard working only when starter is pressed - but i think this is OK.

Fuel pump in this model only works when pressing the starter button by design (I THINK I read somewhere that more advanced model pre-pressure by operating the fuel pump before starter button is pressed)

I hope I understood corretly what you requested of me.

Thank you,
Roy

This morning I sent the following Email to Roy and I thing that everybody can use a bit of extra information:

The only problem with removing the injector is that you will have to replace the O-rings. Knowing your difficulties to get parts, I would keep it as the last option. I cannot see 4 injectors going at the same time.
If one was bad, your engine would start on 3 cylinders.
If one stay permanently open, you would lose the pressure for the other one and the particular cylinder would be flooded all the time.
The two easy test that I will conduct would be:
- Put a manometer in line with the fuel injector ramp and test if there is pressure.
- Test if you get power going to the fuel injector.
On the K100 engine, the 4 fuel injectors open at the same time.
The positive is always on (when the ignition switch is turn on) and the EFI computer controls the negative.
Is your positive going to the injectors? If not, it could simply be a bad relay. ( in the electrical tray under the tank).

One other question is: In the US, the K100 was equipped with an "altitude correction plug". This never work and was later removed. Would you have one on your bike? If yes, just remove it and jump the connections.
Follow is a couple of pictures to complement my information:

Hi Roy,
Thanks for performing the test, what you verified with the Kill Switch test is that the Kill Switch and wiring to it is not faulty which is good news and that has been eliminated as a fault. We know you have some pressure when starting so the pump runs otherwise you could not have pumped fuel out.

Unplug an injector electrical connector and with the ignition turned on test the connections in the plug with a voltage not current meter you should see + 12 volts on one and nothing on the other. Also operate the start button. Check if you still see + 12 volts on one, as said above the relay supplies 12 volts and the EFI computer supplies a train of earth pulses to operate the injectors so as to dispense fuel. Check to see 12 volts on the injectors and report back
Regards,
K-BIKE

K-BIKE wrote:We know you have some pressure when starting so the pump runs otherwise you could not have pumped fuel out.
K-BIKE

I would make some comments about this statement...

First in general a pump will never build pressure but provides flow. In the case of the BMW fuel pump, a relief valve is built in the unit and the output is 4.5 bars(or 65 psi). This is higher than what is required by the EFI system. To regulate the pressure at 36psi, BMW has installed an external pressure regulator (or relief valve).

As everybody knows, one of the principle of hydraulic is that the liquid will always uses the path of least resistance.(This applies to electricity too)
If the external regulator has any sort of problem (ie:broken internal spring) all the pressure built by the pump will be dumped back to the tank and the result will be only flow to your fuel injectors (Not good).
If the fuel pump has an internal leak, the same thing will happen and the pump pressure will be dumped back to the tank as soon as you restrict the flow.

Now after typing this, I recognized that I missleaded Roy in my explanation.
If you unplug the hose coming from the tank and plug a manometer to it, you should get around the 65psi provided by the pump.
if you install a tee in line with the hose, you should get only 36psi because the external regulator will drop the pressure.
The second test is really the best one in his case.

I really like this post as so many people are sharing their opinion and expertise. At the end, we will put his bike back on the road and we will learn a lot. This is great!

Thanks a lot to all the posters.

Been following this interesting problem. Can I make what may be a stupid suggestion? Sometimes they do work!
Because Roy used an unfamiliar filling station, could he have filled up with diesel by mistake?
Car drivers around here seem to do this a lot and it probably would drive for a kilometre afterwards using petrol in the filter and fuel line.
Maybe our more experienced brethren could suggest what to look for. Clogged injectors perhaps?
As I said, may be a daft idea but I know how frustrating these things can be and sometimes it can be the most obvious.

Hi Roy,
OK standing back what do we know,
You have sparks so the engine is turning over and the Hall Effect units are producing sparks otherwise you would not see sparks at the spark plugs.

Also we know that your comment is there is not much fuel smell> so I am sure we are not injecting any fuel.

I discount sudden blockage of the air filter as that can only happen over days with rodents or squirrels using the airbox as a granary and we know there are no squirrels and it happened overnight. That sort of blockage happens over weeks or at least many days not overnight.

We know the fuel pump runs but taking Crazy Frog's point we don't know what pressure is on the rail but given it pumps fuel I tend to discount sudden failure of the pressure regulator but that certainly is the next check to follow.

The simplest check you can do right now is to check injector plug voltage, I am suspicious we will not find power on the injector when you check with a meter when the ignition is on. If that is the case then check the feed to the relay in the relay box as that is a likely suspect.

Silly of me I know at this stage to ask but I suppose you have checked all of the fuses are intact and making good contact both sides. I recall your comment about funny smell and just wondered if an intermittent short had popped a fuse.

So let us know what you find when you check the injector plug socket.
Regards,
K-BIKE

Excellent point about diesel fill up I would have thought it would get through before the 1K and make it misbehave but the smell of diesel is easy to spot so really well worth a check.
Regards,
K-BIKE

Comberjohn wrote:Been following this interesting problem. Can I make what may be a stupid suggestion? Sometimes they do work!
Because Roy used an unfamiliar filling station, could he have filled up with diesel by mistake?
Car drivers around here seem to do this a lot and it probably would drive for a kilometre afterwards using petrol in the filter and fuel line.
Maybe our more experienced brethren could suggest what to look for. Clogged injectors perhaps?
As I said, may be a daft idea but I know how frustrating these things can be and sometimes it can be the most obvious.

Hi,

Interesting point.


The diesel filling gun here has a special yellow cover u need to take off before filling up - which reduces these mistakes but everything is possible.

Fuel in tank did smell like petrol.

I have replaced all fuel and disconnecting the fuel line used the starter button to squirt out remaining fuel in tank - and the fuel pumps distinguished sound is loud and clear.

The fuel now in tank is same as one in my car, from same filling station at same time, and car ran fine (before o wreked it).

Both Bert and kbike suggest I examine injector plug voltage - I will do that. Today (sunday) is my 1st day back at work after accident and I hope to these tests earliest.

but I think your point that maybe the injectors ALL gummed up at once because of Diesel (other bad stuff in fuel) is possible. And I will test this later.

Thank you,
Roy

K-BIKE wrote:Hi Roy,
OK standing back what do we know,
You have sparks so the engine is turning over and the Hall Effect units are producing sparks otherwise you would not see sparks at the spark plugs.

Also we know that your comment is there is not much fuel smell> so I am sure we are not injecting any fuel.

I discount sudden blockage of the air filter as that can only happen over days with rodents or squirrels using the airbox as a granary and we know there are no squirrels and it happened overnight. That sort of blockage happens over weeks or at least many days not overnight.

We know the fuel pump runs but taking Crazy Frog's point we don't know what pressure is on the rail but given it pumps fuel I tend to discount sudden failure of the pressure regulator but that certainly is the next check to follow.

The simplest check you can do right now is to check injector plug voltage, I am suspicious we will not find power on the injector when you check with a meter when the ignition is on. If that is the case then check the feed to the relay in the relay box as that is a likely suspect.

Silly of me I know at this stage to ask but I suppose you have checked all of the fuses are intact and making good contact both sides. I recall your comment about funny smell and just wondered if an intermittent short had popped a fuse.

So let us know what you find when you check the injector plug socket.
Regards,
K-BIKE

Hi,

Fuses:
I did check all the fuses, taken them out, they seem OK, cleaned and returned. I will replace them all as this is very easy to do.

injector plug voltage: will be my next test - If I understood Bert corretly all get same pulses so if I disconnect the connector from one then I can measure there (negative on bike body, looking for positive pulse). I do wonder , the pulse is supposed to be very short, How will I see it on the measuring device?)

I am less sure how to test if fuel relay is getting /passing any electricity (they are relatively in expensive and I shall order a spare regardless).

Fuel pressure:
I will try to obtain a manometer to test this.

Today (Sun) is my 1st day back at work - but I will try to run these tests soonest.

Thank you
Roy

Hi Roy,
The positive should be continuous when ignition is on, in order to operate the injectors receive a stream of earth signals from the EFI computer giving an earth return for the injector via the EFI computer.

So the check is to see if when you turn on the key the 12 volts supply is present and stays present when you spin over the starter. If it is not present or disappears when the starter operates no fuel will get to the engine even if the pressure is perfect in the fuel rail.
Regards,
K-BIKE

Just a quick note so as not to add more confusion.

The FI relay has to be working otherwise the fuel pump would not run but the positive for the injectors comes off the same relay so if not present would indicate a broken wire or bad connection between the injectors and the relay.

Might not be a bad idea if not already to start a written check list and cross off one thing one at a time as there are an enormous number of variables and a massive amount of information being thrown about.

There is also the hideous but rare option of two simultaneous faults. It has happened to me on electro mechanical equipment and a bike is no different so we might need to take a step back and tick off one thing at a time and it will get sorted.

Regards,

Phil

Hi Roy,
On the base diagram for your bike the fuel injection relay is shown as having two poles commoned on pin 30 in the base and directly connected to the battery with no fuse in line.

One pole out the relay 87b supplies via fuse 6 to the fuel level sensor and the fuel pump (we know fuse 6 is OK as the pump runs).

The other pole of the fuel injection relay (pin 87) supplies direct via plugs and sockets the fuel injectors and is connected to pin 9 on the EFI computer.

Interestingly or annoyingly the official BMW circuit diagram for your model shows two types of relay one with one pole and one with two dependant upon which diagram one looks at. The full circuit diagram shows a double pole relay whereas the engine electrics only diagram shows a single pole relay grrr.

Both diagrams however show the power for the injectors going via a multi-pin plug whereas the power to the fuel pump does not go via that plug! So the plug is a point where all else would work except if there was a bad connection then that plug will stop the 12 volts for the injectors which would stop the injectors opening.

Regards,
K-BIKE

K-BIKE wrote:Hi Roy,
On the base diagram for your bike the fuel injection relay is shown as having two poles commoned on pin 30 in the base and directly connected to the battery with no fuse in line.

One pole out the relay 87b supplies via fuse 6 to the fuel level sensor and the fuel pump (we know fuse 6 is OK as the pump runs).

The other pole of the fuel injection relay (pin 87) supplies direct via plugs and sockets the fuel injectors and is connected to pin 9 on the EFI computer.

Interestingly or annoyingly the official BMW circuit diagram for your model shows two types of relay one with one pole and one with two dependant upon which diagram one looks at. The full circuit diagram shows a double pole relay whereas the engine electrics only diagram shows a single pole relay grrr.

Both diagrams however show the power for the injectors going via a multi-pin plug whereas the power to the fuel pump does not go via that plug! So the plug is a point where all else would work except if there was a bad connection then that plug will stop the 12 volts for the injectors which would stop the injectors opening.

Regards,
K-BIKE

Thank you very much for this info- seems this problem is a real learning experience for me, especialy as yours and Bert's explanations help me better understand what i read in the manuals. I will go thru some tests as soon as I can, now that my "vacation" is over I need to handle many things at work.

I have ordered some relays from motobins, hope they will arrive within 10 days. Regardles it is good to have some around for testing.

Roy

K-BIKE wrote:Hi Roy,
On the base diagram for your bike the fuel injection relay is shown as having two poles commoned on pin 30 in the base and directly connected to the battery with no fuse in line.

One pole out the relay 87b supplies via fuse 6 to the fuel level sensor and the fuel pump (we know fuse 6 is OK as the pump runs).

The other pole of the fuel injection relay (pin 87) supplies direct via plugs and sockets the fuel injectors and is connected to pin 9 on the EFI computer.

Interestingly or annoyingly the official BMW circuit diagram for your model shows two types of relay one with one pole and one with two dependant upon which diagram one looks at. The full circuit diagram shows a double pole relay whereas the engine electrics only diagram shows a single pole relay grrr.

Both diagrams however show the power for the injectors going via a multi-pin plug whereas the power to the fuel pump does not go via that plug! So the plug is a point where all else would work except if there was a bad connection then that plug will stop the 12 volts for the injectors which would stop the injectors opening.

Regards,
K-BIKE

Hi,

I did some of the tests and here are the results - all ideas are welcome.

I measured on the rear most injector plug 9.2 to 9.4 V. this is after cleaning with contact cleaner and slightly scratching engine cover with the grd wire of multimeter.

Can anyone tell me what actual measurments he has made on in injector plugs?

pls note Battery is down to 11.4 V from 12.4 a month ago.

BTW, I found in HYNES manual a disquieting paragrapph:
"NEVER attempt to test either the trigger assembly or the control unit using equipment which has its own source (eg multimeters.....); the applied voltage may damage one or more of their sensetive circuits"

I hope I have not done any damage with the battery operated multimeter.

I have not as yet found a proper manometer.

Thank you,
Roy

Hi Roy,
Worry not about tests with a voltmeter they impose such a small load on the circuit it will not be noticed, you were after all testing voltage not ohms and the voltage comes direct from the bike battery via the relay. Now the Haynes manual coverage of fuel injection is absolutely useless other than in bad English raising all sorts of fears. I would not recommend you test OHMS with your meter but testing the output from the battery via a relay cannot do harm.

I am surprised to see that you have lost 2 volts just passing down a few wires through a relay and down to the injector plug. Given the meter draws next to no current and the injectors draw quite a lot of current that is surprisingly low.

Also if the battery is down to 11.4 you need to get it onto a trickle charger pronto and charge it back up. I keep my battery on a charger at a constant 13.6 volts the same as we do for sealed burglar alarm batteries. The charger is also current limited to prevent overcharging with a flat battery, but primarily balances the very slight drain from the bike alarm the insurance company insisted upon.
Regards,
K-BIKE

Kbike is right (as always)

When you measure voltage, the only power from your tester goes to the digital display.
When you measure a resistance, you have to send power in order to get some result. I don't know how many volts your sending with the meter, but it is minimal.
By the way, if you want to understand the basic of Ohms law, check this site:
Electrical formulas

It seems that Roy gets power (at least the positive) to the fuel injectors. It proves that the relay is OK.
As Roy has difficulties (parts are very expensive in Israel), he followed my advise and started to bid on the basic electronic equipment on Ebay. Please don't over bid him. He's in a bind and needs his bike back on the road.
I would not be surprised that there is a problem with the pressure regulator or the EFI computer.
Time will tell
On the bright side, Roy is learning a lot about his bike and we do too.
Thanks Roy for picking up our brain (or what is left).

Hi Folks,
I went and measured the voltage on the fuel injection rail on my K100 RS 4V which has a slightly different FI set-up in that the power is not on all the time but is only on whilst the pump runs which is about 1 1/2 seconds when you turn on the ignition. The crunch is the voltage is only 0.4 volts below the voltage measured off the battery so with a 2 volt drop I begin to suspect that Roy has a bad joint or a duff relay contact, especially as his circuit diagram shows two relay contacts only one of which supplies the fuel pump and the other the injectors. Roy can I suggest you whip the tank off (easier said than done and take out the relay and check for any poor connections with its socket and its base.
Regards,
K-BIKE

K-BIKE wrote:Hi Roy,
Worry not about tests with a voltmeter they impose such a small load on the circuit it will not be noticed, you were after all testing voltage not ohms and the voltage comes direct from the bike battery via the relay. Now the Haynes manual coverage of fuel injection is absolutely useless other than in bad English raising all sorts of fears. I would not recommend you test OHMS with your meter but testing the output from the battery via a relay cannot do harm.

I am surprised to see that you have lost 2 volts just passing down a few wires through a relay and down to the injector plug. Given the meter draws next to no current and the injectors draw quite a lot of current that is surprisingly low.

Also if the battery is down to 11.4 you need to get it onto a trickle charger pronto and charge it back up. I keep my battery on a charger at a constant 13.6 volts the same as we do for sealed burglar alarm batteries. The charger is also current limited to prevent overcharging with a flat battery, but primarily balances the very slight drain from the bike alarm the insurance company insisted upon.
Regards,
K-BIKE

I am ordering a battery charger. Following other conversations I had, Do you think replacing the grd wire with a heavier duty one is a good idea, can it be relevant to the lost 2v?

thank you,
Roy

Crazy Frog wrote:Kbike is right (as always)

When you measure voltage, the only power from your tester goes to the digital display.
When you measure a resistance, you have to send power in order to get some result. I don't know how many volts your sending with the meter, but it is minimal.
By the way, if you want to understand the basic of Ohms law, check this site:
Electrical formulas

It seems that Roy gets power (at least the positive) to the fuel injectors. It proves that the relay is OK.
As Roy has difficulties (parts are very expensive in Israel), he followed my advise and started to bid on the basic electronic equipment on Ebay. Please don't over bid him. He's in a bind and needs his bike back on the road.
I would not be surprised that there is a problem with the pressure regulator or the EFI computer.
Time will tell
On the bright side, Roy is learning a lot about his bike and we do too.
Thanks Roy for picking up our brain (or what is left).

----------------------
Hi Bert,

I think the advice to get spares when I can rather than when I must is one of those "I should have thought of it myself" -and certainly may help in trouble shooting.

I have ordered some relays (new) from motobins in England. And have won 2 bids, both from a 1985 bike (my bike is 1987) for Fuel injection and fuel ignition computers for low price. I am now bidding for an airflow meter.

Have not as yet found a fuel manometer but have found ones used by gas people - do you think it can measure a liquid like fuel passing thru?

Indeed, seeing my learning curve, it seems I am in for a lot of (the) joy... of learning.

Seriously now, I think the camaraderie shown on this forum is a good part of the bike experience for me. I do hope to be able to help others in future.

I hope others reading these posts benefit from them and don't see them as a total bore - sorry guys.

BTW - I have am reading relevant chapter in both HAYNES and CLIMER and have found 2-3 interesting sugestions and will post them soon.

Thank you,
Roy

K-BIKE wrote:Hi Folks,
I went and measured the voltage on the fuel injection rail on my K100 RS 4V which has a slightly different FI set-up in that the power is not on all the time but is only on whilst the pump runs which is about 1 1/2 seconds when you turn on the ignition. The crunch is the voltage is only 0.4 volts below the voltage measured off the battery so with a 2 volt drop I begin to suspect that Roy has a bad joint or a duff relay contact, especially as his circuit diagram shows two relay contacts only one of which supplies the fuel pump and the other the injectors. Roy can I suggest you whip the tank off (easier said than done and take out the relay and check for any poor connections with its socket and its base.
Regards,
K-BIKE

Hi,

Thank you fo making the tests.
I am already an expert in fuel tank removal..
I have removed most relays and used contact cleaner there and have ordered new fuel relays just in case.

Sorry for being so dense but how do I "check for any poor connections with its socket and its base"?

Also - pls see Q on replacing grd wire with a heavier duty one - can this be relevant to V drop (but then should I have not seen same drop everywhere)?

Thank you,
Roy

Hi Roy, The first thing to look at is the condition of the relay pins are they bright and shiny or tarnished. If they are tarnished is there a clean scratch where the relay socket has scratched through the tarnish to clean metal? that would be better than even tarnish. With regard to contact cleaner I am interested to know what you are using, many of them are just a solvent spray degreaser. The trick is to have bright shiny clean contacts and give them the Deoxit treatment. The fuel injection relay is nothing special and niggling away in my memory is the thought that you can swap the relay with one of the others but I will check. Can you tell me how many pins are on your FI relay when you pull it out and look at its bottom so to speak?

With regard to earth connections there was an excellent post from Fluke on the importance of good grounds on EFI systems and how much trouble and replacement by dumb techs is due to failure to check and fix bad earth grounds. There are a number of earth grounds on the BMW K Bike and these need to be

disassembled

thoroughly burnished Deoxited and screwed back together. Same with the battery terminals and the extra wires that piggyback onto the terminal posts of the battery.

I used to have the Fluke post and if I can find it I will post it in the downloads section as it is very thought provoking.

As the bike did work I would change no physical device or wire until you have proved it faulty. Sure in the future put in a heavier wire in parallel with the current one to improve earth ground but first off clean all terminations on the circuit including all chassis earths. The circuit diagram shows a plug and shoket in line with the injectors and the relay check that out too.
Regards,
K-BIKE

K-BIKE wrote:Hi Roy, The first thing to look at is the condition of the relay pins are they bright and shiny or tarnished. If they are tarnished is there a clean scratch where the relay socket has scratched through the tarnish to clean metal? that would be better than even tarnish. With regard to contact cleaner I am interested to know what you are using, many of them are just a solvent spray degreaser. The trick is to have bright shiny clean contacts and give them the Deoxit treatment. The fuel injection relay is nothing special and niggling away in my memory is the thought that you can swap the relay with one of the others but I will check. Can you tell me how many pins are on your FI relay when you pull it out and look at its bottom so to speak?

With regard to earth connections there was an excellent post from Fluke on the importance of good grounds on EFI systems and how much trouble and replacement by dumb techs is due to failure to check and fix bad earth grounds. There are a number of earth grounds on the BMW K Bike and these need to be

disassembled

thoroughly burnished Deoxited and screwed back together. Same with the battery terminals and the extra wires that piggyback onto the terminal posts of the battery.

I used to have the Fluke post and if I can find it I will post it in the downloads section as it is very thought provoking.

As the bike did work I would change no physical device or wire until you have proved it faulty. Sure in the future put in a heavier wire in parallel with the current one to improve earth ground but first off clean all terminations on the circuit including all chassis earths. The circuit diagram shows a plug and shoket in line with the injectors and the relay check that out too.
Regards,
K-BIKE

Will do.

Yesterday I got the battery charger and hoefully will do some more TS this weekend.

The contact cleaner is most likely a simple solution.

Roy

A couple of questions in general. 1)If the temperature sensing was reading high temp (extreme) i.e. open or closed circuit depending if it was an NTC, would the FI unit allow the bike to start?

2) If the throttle position switch was dud and reading wide open throttle or open circuit what would happen?

3) Anybody got a spare fuel injector to see what voltage they open at?

Regards,

Phil

Phil,

You have a very good point.

In a previous post, I indicated that the EFI computer DOESN'T take the engine temperature in consideration if it runs at less than 900rpm. (This was stated in the course notes of a BMW technician.) BUT...

I just remember reading on another forum (maybe 2 years ago) that the K bike has a security feature that prevents you to restart the bike if the temperature exceeds the maximum permitted. (it has to cool down first). Would it be possible that the EFI computer checks only if the temperature is high (ie; the lead that triggers the temperature light on your dash)?

QUESTION FOR ROY:
Is the temperature light on the dash ON when you turn on your ignition? I think that it should be OFF if you just turn your ignition on.

Hi,
I went and tested my 4Valve and the following happens when I turn on the ignition without the engine running - all warning lights including temperature come on except the choke and low fuel level. If I turn the choke lever the choke light comes on. I will need to check the fuel float as I have not run low on fuel for the last three fills and hence have not seen it on.
Regards,
K-BIKE

Sorry Bert I re-read your post before I made my comment but missed the bit about the temperature sensor. I am trying to cross all the "I's" and dot the "T's"????

Interesting difference between the 2V and 4V. How do you know if the temperature sensor is working or the bulb is blown on the early model. It appears they fixed it on the later models.

Regards,

Phil

Yes, I just went to check my bike (very cold outside) and the high temperature light doesn't light on when you turn your ignition on.
This is the same on the 1986 K75.

Crazy Frog wrote:Phil,

You have a very good point.

In a previous post, I indicated that the EFI computer DOESN'T take the engine temperature in consideration if it runs at less than 900rpm. (This was stated in the course notes of a BMW technician.) BUT...

I just remember reading on another forum (maybe 2 years ago) that the K bike has a security feature that prevents you to restart the bike if the temperature exceeds the maximum permitted. (it has to cool down first). Would it be possible that the EFI computer checks only if the temperature is high (ie; the lead that triggers the temperature light on your dash)?

QUESTION FOR ROY:
Is the temperature light on the dash ON when you turn on your ignition? I think that it should be OFF if you just turn your ignition on.

Hi,

I checked and when I turn on the ignition tem light is NOT on.

Roy in an email has identified that Haynes and Clymer are very flaky with regard to what relay does what in the relay box. Just for completeness of the thread I sent him the following troubleshooting notes to determine which relay does what. In case anyone needs to do this here is what I sent him.
.hmmessage P {
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BODY.hmmessage {
FONT-SIZE: 10pt; FONT-FAMILY: Verdana
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Hi Roy,
First off we know the fuel pump runs via the fuel
injection relay what we did know was if your relay had five contacts, so thanks
to you at least it shows one of the diagrams BMW has published on their CD of
circuit diagrams which I have here applies to your bike you have a
five pin relay.

So can I suggest that you do a little test.
reconnect your tank petrol pipes and plug the tank in rest it on top with the
relay box cover off. Turn on and verify fuel pump runs in the conditions it did
before. Then gently raise the tank, probably would help to prop it with a book
or something. Then pull out the relay you believe to be the fuel pump relay and
then check to see if that has prevented the pump running when you repeat the
process that normally runs the fuel pump. If the pump still runs then try and
toot the horn if it sounds that is not the horn relay.

If it has stopped the pump then replace the
relay and repeat the test again confirm the pump now runs?

OK then remove the other relay and repeat the
test again the pump should run as only the fuel relay should stop the pump if
the engine is starting or running I think. When the relay is out and ignition is
on try and toot the horn if it does not sound you have found the horn
relay.

Tell me what happens this test should confirm
which is the fuel pump relay the other is the horn relay or load shedding
relay.

I was able to cut and paste the list of
components from the circuit diagram for your bike as you can see. I particularly
like number 5 the "cattery" perhaps that is so named because of the howl all BMW owners
give out when they are told the price of a genuine BMW battery :-)

Still all jokes aside I can only see fuel
injection, starter, load shedding and horn relays no others listed so that lines
up with the three relays you have and the big chunky starter relay is wired direct
to the cattery :-)

1		instrument
	a)	speedometer
	b)	revolution counter
	c)	4 x instrument lighting
	d)	Charge-current warning light (red)
	e)	not used
	f)	gear indicator
	g)	Neutral telltale light (green)
	h)	Oil-pressure warning light (red)
	i)	clock
	k)	Turn signal repeater, left and right (green)
	l)	High-beam headlight telltale light (blue)
	m)	Choke telltale light (orange)
	n)	Coolant temperature high (red)
	o)	2 x fuel indicator (red and orange)
	p)	Bulb telltale light (red)
2		lnductive sensor
3		gearbox switch
4		generator
5		cattery
6		temperature sensor
7		oil pressure switch
8		temperature switchbox
9		fan motor
10		flashing turn-indicator unit
11		fuel-level sensor
12		Fanfare horn, left
13		Fanfare horn, right
14		Multifunction switch, right
	a)	light switch
	b)	Turn-indicator switch, right
	c)	emergency off switch, kill switch
	d)	starter switch
	e)	turn-indicator cancel switch
15		Multifunction switch, left
	a)	horn switch
	b)	high-beam headlight switch
	c)	Turn-indicator switch, left
23		Turn indicator, front left
24		Turn indicator, front right
25		Turn indicator, rear left
26		Turn indicator, rear right
27		Hazard warning lights switch (optional extra)
28		rear light
29		Hall-effect transmitter II
30		Switching device for ignition
31		Hall-effect transmitter I
32		Ignition coil 1
33		Ignition coil 2
34		bulb monitoring unit
35		Brake-light switch, front
36		Brake-light switch, rear
37		brake light
38		parking light
39		not used
40		fuel injection relay
41		Fuse box
42		ignition lock
43		starter relay
44		load-shedding relay
45		clutch switch
46		Control unit for LE-Jetronic
47		airflow meter
48		throttle-valve switch
49		Valve 1
50		Valve 2
51		Valve 3
52		Valve 4
53		Fuel pump
54		starter motor
55		not used
56		not used
57		not used
58		not used
59		not used
60		horn relay
61		headlight
62		not used
63		spark plugs
64		differential pressure switch
65		choke switch
66		Connection for heated handlebar grips (optional extra)
67		Connection for optional extras
68		Connection for anti-theft alarm (optional extra)
69		Box for additional instruments
70		Connection for additional instruments

Regards,
K-BIKE

[quote="K-BIKE"]Roy in an email has identified that Haynes and Clymer are very flaky with regard to what relay does what in the relay box. Just for completeness of the thread I sent him the following troubleshooting notes to determine which relay does what. In case anyone needs to do this here is what I sent him.
.hmmessage P {
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}
BODY.hmmessage {
FONT-SIZE: 10pt; FONT-FAMILY: Verdana
}
Hi Roy,
First off we know the fuel pump runs via the fuel
injection relay what we did know was if your relay had five contacts, so thanks
to you at least it shows one of the diagrams BMW has published on their CD of
circuit diagrams which I have here applies to your bike you have a
five pin relay.

So can I suggest that you do a little test.
reconnect your tank petrol pipes and plug the tank in rest it on top with the
relay box cover off. Turn on and verify fuel pump runs in the conditions it did
before. Then gently raise the tank, probably would help to prop it with a book
or something. Then pull out the relay you believe to be the fuel pump relay and
then check to see if that has prevented the pump running when you repeat the
process that normally runs the fuel pump. If the pump still runs then try and
toot the horn if it sounds that is not the horn relay.

If it has stopped the pump then replace the
relay and repeat the test again confirm the pump now runs?

OK then remove the other relay and repeat the
test again the pump should run as only the fuel relay should stop the pump if
the engine is starting or running I think. When the relay is out and ignition is
on try and toot the horn if it does not sound you have found the horn
relay.

Tell me what happens this test should confirm
which is the fuel pump relay the other is the horn relay or load shedding
relay.

I was able to cut and paste the list of
components from the circuit diagram for your bike as you can see. I particularly
like number 5 the "cattery" perhaps that is so named because of the howl all BMW owners
give out when they are told the price of a genuine BMW battery :-)

Still all jokes aside I can only see fuel
injection, starter, load shedding and horn relays no others listed so that lines
up with the three relays you have and the big chunky starter relay is wired direct
to the cattery :-)

-------------------------------------





Hi,



I performed the tests. great idea to keep the tank on - very easy to put a hand in and remove /add relays.



left most at front is the fuel pump.

center front is horn (and lights do not turn on either)

did not remove right front, which I guess we need to now assume is the power shedding relay as I do not have replacement for this one. However it seems to work because when I "start" then engine the lights go out.



more info:

I did 8-10 3-5 seconds (and a few longer) attempts to start in sequence with perhaps 2 secs between attempts. I stopped there as I do not know what kind of duty cycle the starter can take.

Some observations:

1. same "dry cough" - not a single misfire.
   
2. engine seems to be turning powerfully by starter as hand on exhaust feels the air being pumped out (I now have an air motorcycle - very green).
   
3. Very little to no gas smell in exust.
   

Is it time to try to remove injectors and see if they squirt fuel? If so then I will wait till new ones ordered arrive so I can replace if necessary. Now IF injectors do not "fire" then what do we suspect then?



Much Obliged,

Roy

Here is a long posting from Roy summing up what he found on the fuel injector relay.
There is so much confusion and it seems that nobody has a real anwswer yet.
Too big to be posted but click here to get it as a PDF format

According to the color schematic that I posted in the download section, the bike has only 3 relays + the starter relay. This is the schematic for a 1985 and seems to match what the majority of us found on their bike.
If you check the ETK, the electrical tray has only 3 relays + the starter relay. 2 are identical (#13) which should be the horn relay and the fuel injection relay. The third one (#15) is the load shed relay.
If BMW gives them as identical, It should not be any problems to switch them. (I think I did it before)

Hi Roy,
Try a quick test, as the two 5 pin relays are similar, try swapping the horn relay for the fuel injection relay it is a recognised check when you know the horn relay works and check to make sure the fuel tank pipes are connected the right way round after so many on and off tank removals. Then try it to see if it will start.
Regards,
K-BIKE

K-BIKE wrote:Hi Roy,
Try a quick test, as the two 5 pin relays are similar, try swapping the horn relay for the fuel injection relay it is a recognised check when you know the horn relay works and check to make sure the fuel tank pipes are connected the right way round after so many on and off tank removals. Then try it to see if it will start.
Regards,
K-BIKE

hi,

I replaced the left most relay and the center relay with a new ones from motobins - leftmost is necessary for fuel pump to work - Center for horn and light. But bike still will not start.

I do not have a replacment relay for right mostone - I hesitate to swap it with the oneson left as they do not seem to be same (different codes and schematic on them).

Roy

Crazy Frog wrote:Here is a long posting from Roy summing up what he found on the fuel injector relay.
There is so much confusion and it seems that nobody has a real anwswer yet.
Too big to be posted but click here to get it as a PDF format

According to the color schematic that I posted in the download section, the bike has only 3 relays + the starter relay. This is the schematic for a 1985 and seems to match what the majority of us found on their bike.
If you check the ETK, the electrical tray has only 3 relays + the starter relay. 2 are identical (#13) which should be the horn relay and the fuel injection relay. The third one (#15) is the load shed relay.
If BMW gives them as identical, It should not be any problems to switch them. (I think I did it before)

Hi all,

In my PDF u will find data from 4 sources, all of which I have: HAYNESS, CLYMER, BMW service Manual, BMW CD. They are in disagreement. I think we can agree that last two can be considered more reliable but situation seems "dirtier" then that.

Things are further complicated by fact that the BMW cd (same as Bert Quote) shows top (forward) center and right side relays to be same (#13) BUT that is not so in my bike. The center relay has 4 prongs and the right side one 5 prongs and they are abviousely different (I can give the specs).

Leftmost and center I replaced with new obtained from "motobins" - bike will still not run. Rightmost I have no replacment - not sure what to order as we still have not identifies them by name.

Starter is strong and I feel dry puffs of air coming from exhust. not a singlr misfire and practicaly NO gas smell even when one would expect to get a flodded smelly engine. I added 2nd grd wire and cleaned all contacts - no V drop from battery to any point on frame or engine now.

It's a bit of a pain (but can be done without disconnecting fuell tank as k-bike has shown) but perhaps we can together, for benefit of all, collect some real world info concerning this first row or relays?

I am missing out on wonderfull cool and dry winter riding days and would be gratefull for all ideas on this problem.
Roy

Hi Folks,
First and foremost when troubleshooting it is a slow and iterative process testing and measuring as you go. Now Roy has changed the relay what voltage is on the injector when cranking I remember it was 2 volts down which is way too much voltage drop for a connection to the battery via a relay contact.

Is the voltage still 2 volts down if so, and you are confident the replacement relay is OK, then it is an annoying job of tracing the wiring back from the injectors via the plug & socket shown on the drawings which may need cleaning up and then checking and cleaning the earth point for the various electrical bits including the earth for the EFI "computer" As the Fluke manual says a poor earth there will give rise to all sorts of issues.

We will get there and get the bike running but fault finding is a tedious and painstaking process.

Contrast that with the modern garage where a PFY (pimply faced youth) merely replaces ever more expensive bits until the bike starts working again and NO WAY do they put the bits back that were not the problem, no you just paid for the PFY's learning experience
Regards,
K-Bike

Hi al

I am corresponding from the "other" my bike won't start post.

I am at the same last stage as this post so either see the "other" or read this background:
1986 K100RS 2V

Won' start...Fixed fuel pump, fuses etc etc

My relays are as follows:

1. Front left = 5 pin (larger than the RHS 2X)
2. Next front (moving right!) = blank socket
3. next one is Hella Brand 4 pin
4. Front Right is also a Hella Brand 4 pin

#3 and #4 interchange and the horn and lights(???) work - I am not sure which relay runs the lights as the front fairing/lights is off... If I remove either of these two relays the horn (and I suppose the lights) stop working.

I am assuming the fuel pump relay is the Front Left #1 relay as indicated in the Paul Glaves article on Electrical Box Content from http://www.ibmwr.org/ktech.shtml

So, I suppose I can't readily see if the LHS 5 pin relay is not working - which isn't giving me 12 volts at the injector voltage connections (as per my "other" won't start post)

Question: is my description of the front row relays correct?

Regards

Mal WELLS

God this is getting confusing, and I say nothing like consistency, and it appears this is nothing like it on these models!
Mal your description of relays is similar to mine but from the sound of things more like Roy's.

Mine (1984) is LHS Fuel pump relay 5 pins. No2 is blank. No3 BMW 30A load shed relay 5 pins apparently interchangeable with No1 and No4 is Hella 4 pin horn relay.




Fuel Pump/Fuel Injection



Load Shed Relay (5 Pins)



Horn Relay (4 Pins)

So the plot thickens in that if your fuel pump is working then you should have 12V on your injector (according to the circuit diagram) however there is a plug in-between the relay and the injector which I think is the one I have disconnected below as the thick green/red wire at the very least connects to the relay.

Good man if that is indeed the plug shown on the circuit diagrams it is an excellent place to check for bad contacts.
Regards,
K-BIKE

Hi Phil

Another day...More investigation and reading last night has found:

My number 1 relay is the same as your picture. It is an original BMW 1 373 912.3 five pin relay.

However my second relay (which I thought was for the headlights! I'm a dummy!) and is, as you have stated, for the load shedding is in fact a duplicate 4 pin Hella that runs the horn relay.

All I can think of is that at some stage the load shedding was replaced with a Hella 4 pin. I will need to remove the tank (again) and investigate whether the load shedding socket is 4 or 5 pin. If it is 5 pin then I assume I need to get a proper replacement? Internet search has indicated a Tyco/Bosch replacement part with 5 pins Bosch 0 332 019 150 which has a mounting bracket (just a plastic lug at the top for a screw) or Bosch 0 332 019 150 which has no plastic lug. US$7 so I should just get one!


To add more confusion I am watching Ebay for a complete set of relays from a similar bike which came on line today! the confusion comes from the uncanny resemblance to my setup e.g. one black FI relay and two yellow looking Hellas?


Don't sweat over this as I probably won't do much until the weekend.

Again, thanks

Mal