Approx 8 weeks ago I had to lay down my 92 K100RS to keep from going airborne over the car that had pulled in front of me(and then pulled in front again after stopping so I could go around). This shattered the faring and headlamp and bent the sub-frame that the faring attaches to. The bike started right up after the accident and again 3-4 days later at the shop. After 2-3 weeks the bike was towed home so I could put it back together. It is back together now and refuses to start the following is a rundown on all repairs I made til now:

First I removed the tank to replace the filter and fuel float apparatus. The tank then sat complete in my living room until about 1 week ago. I replaced the air filter. I replaced the fork oil. It should be noted that all fluids (radiator, oil, brakes) were at their pre-crash levels with no evidence of leaks anywhere.

I then set about, when it hasn't been raining lately, replacing the top faring/headlight with items I purchased from Re-psycle parts in Ohio. Everything back together I put the tank back on, charged the battery and no joy. The starter turns strongly but there is no combustion. I replaced the plugs. No combustion. I have tested the pressure of the fuel pump and it is good(>30 psi) so I know I have fuel at the rail. I know I have spark from both coils(tested at cylinders 1 and 2). Still no combustion.

I conversations I have had with Beemer pros across the country, the consensus is that, with all the above, we have 4 faulty injectors. They *are* 20 years old and I have forced this bike to live outside in CA, MA and TX in the last 4 years. Then they sat dry for 4-6 weeks through mostly winter rain, soft covered but still outside. I have been advised to just replace them and also that a good cleaning may revive them. I have tested the injector coils and they all give 16 Ohms as they should.

So the questions: What else could it be besides injectors? Are Bosch injectors @ $89 as good as BMW @$211? Cleaning/rebuild as good as new? TIA

Hi krome,
Before you spend one cent on new bits to get it started follow the diagnosis chart in the Download section. Once you have introduced yourself in the Member Introduction Area Crazy Frog will give you the password to access the download files. So go to it.

As a first tip look at all the things you disconnected are they reconnected especially the fuel pump connector to the cable coming out of the bottom of the tank.

Can you hear the fuel pump start when you turn the ignition key on there should be a few seconds of pump run. Next is the kill switch set on BTDT found out it won't start if it is off. Is the side stand up (only matters if you have the side stand switch) mine does.
Regards,
K-BIKE

Side stand is up and kill is set to on. Fuel pump turns on with key and pumps with start button. Will check DLs.

Turns out I already have that How to doc.

hmm heres a silly idea ...why not check the connector to the brain under the seat ....recently i had a big thump over a rickety bridge on a back road ....and the connector to the efi computer came loose ....

this might explain why everything apears correct but no injection ?

Checked that and connection is tight. Doesn't mean the box isn't shot of course, but...

headlights work ?

My two cents..I had a similar problem. Turns out I had not reconnected the temp probe. The bike would turn over all day but it wont start without this signal. Its cheap as to check this. I came to this solution by working through the flow chart in downloads.

can tell you on the two K100's I restored, both needed the injectors replaced. If left 'out' on their own with no fuel to keep them wet, these old injectors dry out and the varnish on them seals them forever. I've bought one refurbed 'Ford' set for $100, and one used set for $40 and had perfect success with both.

ebay used for $40 shipped: used injectorsI

ebay refurbed for $95 shipped: refurbed Ford injectors

If you go used, just ask them to put 12 volts across them and make sure they 'click' which will confirm they are operational.

Club_c, thanks. That makes sense.

Does your sparkplugs remain dry after several starting attempts?

Have you checked if the injectors getting signal?
The positive current is feed from the same relay as the fuel pump (which working).
The negative side of the coil is grounded through the Motronic unit (which is the pulse signal).

You should also hear that the injectors clicking (with aid of a screwdriver, or stethoscope) when
activating the starter (but it could be difficult with the starter humming in the background).

Inge K.

I've pretty much decided I will stick the injectors back in the rail and see what kind, if any, spray I get from them. Then decide to buy used from one or another source if no good.

If you put 12 volts across the injector pins you should be able to hear it click as you make contact. If not, the injector is sealed shut.

To avoid further headaches, if you can afford it, I would suggest the refurbed units.

I used my spare battery to test each and they seemed OK. I put them back on the rail with my pressure gauge as the end of it and it looks like all are functioning. Odd thing was that when I first turned the key on the pressure only went to 15 psi or so rather than the 36 it should be. I shut it down and did it again and then it was >30 psi(the limit of my gauge). Hit the starter and all injectors were 'spitting' until over-pressure allowed leaks at the gauge. So, some blockage in the rail or maybe when I get it back on it still won't fire and I have to look elsewhere.. Ideas still welcome.

Will it fire on starter fluid?

krome wrote:I put them back on the rail with my pressure gauge as the end of it.

Did you disconnect the fuel return, and connected the gauge to the stub?

You must use a T-piece, and that way you also got the pressure regulator with in the circuit
when measuring the pressure.

It could be that the pressure regulator is stuck open.

Just asking.

Inge K.

good point inge ....we have seen that a few times in here .....

Yeah, I disconnected the return and put my meter on the stub. Interesting point about the pressure regulator. Part I've never seen.

You find a description in the troubleshooting doc. which you said you allready got.
The only difference is that on a 4V you ain`t got the vacum stub.

Inge K.

Yeah. The return line had to be 'coaxed' from its stub so I will have to cut it back a bit and perhaps augment it to get it back on the stub. Looking at the fiche diagram, if it was stuck open I wouldn't be getting the necessary pressure at the rail which may in fact be what's going on. Probably have to wait until next week to look but thanks.

If you have done several starting attempts with your gauge setup, you have achieved an overrich mixture.

It could be a good idea to get the spark plugs out and dry them, use a propane torch...... or hurry up and
throw them into the big hot box in the kitchen, before the turkey walks in.....in a couple of days.

Inge K.

I could use some hints on the best way to get to and remove/replace the pressure regulator should I need to. TIA

the easiest way is to get at it from the riders right hand side ...(its behind the throttle bodies )

it may be helpfull to remove the air cleaner stuff (especially the air feed to the box first )

of corse it requires the removal of the lower fairing

from memory its a phillips head screw

might be easiest to undo the return line at the fuel rail and the tank and draw the whole lot out ....on mine there is some rubbery baffling around the back of the throttle boddies (heat management stuff )

hope that helps

Another place to look is the fuel return line to the tank. Check for kinks I recently replaced mine and thought I wold be generous by adding 40 mm , started the old girl went for a coffee came back and smoke everywhere then refused to start .Plugs showed wet but good spark ,moved tank to check connections and she fired up found the kink near the top of the throttle bodies

hope yours is as simple fix
Cheers Tony

Hi Krome,

Excuse me if this is a silly suggestion but I don't know how far the bike was stripped down. I read that you are getting a spark at the plugs but if the feed wires have been crossed on re-attachment to the ignition coils I believe the sparks will occur near bottom-dead-centre ie: 180 degrees out.

best of luck

Wingless

here is a silly suggestion you havent mixed up the fuel lines where they join onto tank by any chance you wouldn't be the only one thats done it.

Tank lines are fine and ignition wires were never removed at the coils, only at the plugs where they are numbered and of such lengths as they would be really, really difficult to mix up.

2 and 4 are about the same length ...worthwile checking from the coils

But they are all numbered and I was very careful to put them back from where they came.

OK, I have a gauge inline with the fuel pressure regulator and it gives about 35 psi. The injectors are all 'spitting'. I am considering putting it back together with the gauge still on there the see what we've got. Ideas?

36psi is the correct reading so that should be OK. You say the injectors are all spitting, is the fuel comming out as a fine mist or in globs because if it isn't a fine mist then the engine probably wouldnt fire if it is cold. By that I mean ambient temperature cold.

just to clean up the plugs ....they use a wasted spark system ie 1 coil fires through both of the plugs attached ...make sure they fire well and arent wet ...all the way along 1-4

when changing the air filter , you didnt notice if the afm (in the top of the air box )had loose cables ? there is a connector in the airbox ...and check that there is definatly a seal both ends of the pipe between the airbox and plenum

hope that helps

charlie99 wrote:just to clean up the plugs ....they use a wasted spark system ie 1 coil fires through both of the plugs attached ...make sure they fire well and arent wet ...all the way along 1-4

when changing the air filter , you didnt notice if the afm (in the top of the air box )had loose cables ? there is a connector in the airbox ...and check that there is definatly a seal both ends of the pipe between the airbox and plenum

hope that helps

This bike is a 1992 16v and will have a motronic ECU so no MAF (afm) sensor but do make sure there are no leaks in the induction system.

ah ! missed that one mate ...good catch ..

So, I still can't get it to start though I did get a backfire trying the other day. I figured it was just out of gas and put a gallon+ in. I still have the gauge inline with the fuel rail output and now when I try to start it goes up to ~40 psi but then falls back to 0 pretty rapidly. I starts falling even when I am still leaning on the starter. Bad pump? Bad regulator?

One thing you have to do first is try a new set of plugs, cleaning/drying used ones can be an utter waste of time as even as little as 250 combustion cycles without firing can distroy the plugs. I've seen it happen several times and one of the symptoms is backfire. A replacement set of even cheap plugs can work wonders.
If the injectors are squirting any way reasonable the good ol K will start. Pull the rail and turn the engine over and see what kind of spray you have, if its spraying you reg and pump is probably ok. I'm not sure how easy this is to do with the engine in a bike? For me all the bits are easily got at.

AS an alternative to new plugs pour petrol on the tips of the old one and light them thus heating the plug put them back in bike warm and see how you go

krome wrote:So, I still can't get it to start though I did get a backfire trying the other day. I figured it was just out of gas and put a gallon+ in. I still have the gauge inline with the fuel rail output and now when I try to start it goes up to ~40 psi but then falls back to 0 pretty rapidly. I starts falling even when I am still leaning on the starter. Bad pump? Bad regulator?

could be all sorts of things ...fuel line in tank ..has a leak loosing presure ....filter becomming blocked with flow ...bad clamp in tank .... pump just had it ....?

prolly a good idea to undo the last connection to the fuel delivery steel pipe and see if it continues to pump ...or at least do some observing with the cap open ...maybe even the fuel cap assy undone to see properly ...only 4 screws

good luck

Another thought did you run it out of fuel completely ?? may have sucked the crud from the bottom of the tank into the pump either blocking it or strangling it if not filled the filter full of crap ( giving high fuel pump reading then dropping to zero) also may have water in the tank still and finally you did,nt mix the plug leads when putting them back on ( causing the backfire 180 degrees out )

Here's a re-rundown of what has been tried w/out success to get the thing started. It will be C&Ped to others. I have talked to techs in TX, MA, SF and no one has a clue as to what might be keeping it from kicking over. All I get is crank.

Bike started right after crash and I drove it 15 feet onto sidewalk from which it was towed. 3-4 days later I went to the shop where it was stored and it started right up, no hesitation at all. 4 weeks later had it towed to my place where I removed the tank(to replace the float and filter) and renewed the air filter. Another 3 weeks or so and the battery was too low to start it.

Battery charged and still no start.

New plugs(gap checked) no change; crank, no start.

Check for spark and find it at each plug.

Pull injectors and test on extra battery. Find they are functioning and further find that they are visibly 'spitting' fuel, back on the bike.

Fuel pup is directly tested at start conditions and shown to be functioning. Pressure is tested at the end of the fuel rail, as it goes to pressure regulator and is found to be 35-40 PSI as it should be.

No start.

Use starter fluid at air intake, eventually going all the way to spraying directly in the air box. No effect.

All the techs are now talking 'timing' but there is no reason to believe that the timing should ever have been effected and testing timing on a K is more complicated and potentially expensive than just a timing light and a compression gauge. That is one needs to be able to see signals from at least one computer as the engine is turning. The device for doing this runs $3500 or so.

Lone Star BMW here would ask for a minimum $170 up front to even look at it and it would cost $70 to tow it back there(and potentially another $70 to tow it back home if they can't do anything. I don't have this cash right now.

My thoughts have started to look toward seized valves or somesuch. Any new ideas greatly appreciated.

Krome,

When the engine started straight after the crash, and some weeks later it started first kick in the shop, were there any weird mechanical type noises emanating from the engine? Probably not, because you would've mentioned it. So, logically, (stating the bleeding obvious) something has changed from the time you last switched it off, and the next time you tried to start the thing.

If its got fuel and air into the combustion chamber, spark at the correct time, it MUST at least fire.

For what its worth, I took some compression readings at 82,000Km on my 4V K, only when the engine was cold. I haven't done it yet with the engine hot.

All 4 cylinders were 65psi with the throttle closed.
With the throttle fully open I got 95, 90, 90, 95.

The engine sings like a bird, and always starts first kick, even when its been sitting for several weeks.

I don't know of any cheap way to check/test the magic box of electronic wizardry which controls the ignition/fuel injection.

This may be useful if you suspect seized valves.

Rickmeister.

can you confirm that you have checked the temp sender unit connector as albyalbatross has suggested ?

This might sound dumb but have you pulled the return line of the tank and turned the key on to see if you have got fuel all the way to that point. Just another process of elimination thing.

I'm not sure but i think the pump only runs for 15 seconds when you turn the key on (one of the more learned members might no more). It then runs once engine has fired.

Also if when you have tried to start it have you pulled the plugs straight after to see if there is any hint of fuel? The hall effect wiring all in place ok?Nothing electrical has become dislodged.

I know what your saying about the cost of things, plus your towing. Particularly if theres no positive result.

maybe a induction type timing light might help ....you will find that there is a specific timing point in the hall effect sensors location , as there are 2 , use the timing light to check that the flash is indeed occuring when 1 / 4 fires and its the right sensor ...same for 2/3 ....if it was out ...this way you would know real quick ....



just a thought

beanoldboy wrote:can you confirm that you have checked the temp sender unit connector as albyalbatross has suggested ?

I have not as I considered that and the air flow sensor 'ephemera' that couldn't have gone bad just sitting. Now I am forced to look at this stuff too.

when you attempt to start the bike does it sound like it wants to fire?? If you have spark at the plugs fuel is confirmed in chamber she would attempt to fire no matter how far the timing is out even back firing

No attempt to fire, just cranking.

check the computer plug under the seat may have come loose in the accident also you could put fuel in each cylinder using a syringe and see if it tries to start that would count out electrical at least else it could be loose connection or bad joint in the wiring

Plug under the seat is clean and firmly set.

You say 4weeks later towed tank removed float and filter replaced etc . This is the break down point IMHO.