Yes, yet another "not starting".

1985 K100RS.

It's less than 2K km into a new set of plugs and oil, air and fuel filters. After I pulled the tank off and cleaned all electrical connectors as part of diagnosing the headlight, it has been running the sweetest, smoothest and nicest it ever has while I've owned it. This lasted a week.

Then it got torrential rain on it after I got home and went to bed under clear skies and the clouds rolled in while we were all asleep.

Now: The (brand new) battery will crank it vigorously. With NO idle adjust it will catch, sort of just about not quite run while the starter button is depressed, but not idle properly, and die instantly when the starter button is released. With ANY idle adjust, it will turn over, fire, then stop turning. The TPS has been cleaned and pulled off entirely but no change.

I've checked all the easily accessible hose connections and the hoses and plug for the fuel tank. The spark plugs looked okay but I've put new ones in anyway, and nothing. I can't see any water in the tank.

I don't have any more time today to try anything.

Does anyone have any specific ideas for me to start on?

I would start with a check of the plug on the ECU and CDI units . The CDI is fairly good at getting water inside the rubberboot and causing problems.

Check the Hall sensor on the front of the engine for water and possibly even the switch blocks themselves.

And there is a rip roarin storm comming through Stanthorpe so about an hour you may cop it.

similar thing happened to me jh .....after i hit a huge bump on that lions road (over the hill) my injector control unit had come loose on the connector (under the seat ) ...was a quick fix ...but checked most things like you .



would turn over ...almost catch ...if it started would die with any throttle at all



whilst your playing around theres only about 12 odd connections used ....apply deoxIT

Thanks charlie99 and K Freak, that gives me hope.

The storm ended up monstering Beaudesert on the way out to sea, and we only got a ferocious wind up Ipswich way, lucky!

If I'm lucky I'll get time this afternoon to pull the tank off. I'm going to need more deoxIT, though, I'm out!

Well, it's not the connections for the CDI or EFI units.

Now, next point: There is a breather hose behind the engine, from the bottom of the air box to the crankcase (I think). It's a tight S-bend shape and mine is clearly cracked in several places.

What happens when that splits? Is the engine unable to run, or runs with messed-up idle?

I sprayed it liberally with degreaser then tried to start, and it ran almost well for a few seconds, which is the best result yet. This suggests to me there is a problem with the mixture. I'm going to replace it, and treat Hermann to new HT leads at the same time (the leads look fine, but the sockets are filthy, even after I tried to clean them) and I am crossing my fingers very hard.

Any more ideas welcome!

yes that little blighter is a troublesome devil jh ...i just replaced mine on sunday ....the old one is still in good state all the same ....your welcome to it ..

otherwise its a under $30 item that is definatly needed ...ive had no luck finding something similar yet .

Thanks for the offer charlie99, but dammit I've already ordered a replacement from munichmotorcycles!

Your motor does have to be 'airtight' and that means the airbox halves snug against one another, the clamp between the upper airbox and the intake plenum tight and the engine breather hose in good nick as well. It's been written about before but bears repeating: once your bike is idling properly after you've replaced that hose, go round to the right hand side and while it sits chugging away remove the oil filler plug and watch what happens. It wants to die because a whole gulp of air has got in. Same thing with that hose. It can't be cracked or split in any way if you want the bike to run smoothly.

I had the same problem on my old Yamaja XJ600, when one of the two vacuum hoses (the other one operates the fuel tap) came adrift while riding, while I was going to work through morning traffic. It was pure luck that I had extra tools so I could trim the split hose and replaced the lost hose clamp with a bit of wire twisted around the end.

This is one of the reasons I added to the K100's fuel kit with electrical tape, gaffer tape, silicon rescue tape, a multitool and a couple of occy straps. I love the storage space on the K.

aye !!! + 1

And we have a winner!

After the replacement breather hose arrived, and I lost a day to the fact I was going to work when I got the mail and another day to torrential rain, I put the hose on this morning. A bit of I've-been-sitting-for-a-few-days catch on starting, and it idles sweetly again.

I put new HT leads on - customised NGK's, not BMW's, so I don't have those weird little metal tabs any more - and did more electrical contact cleaning.

So: Next project will be putting on the eBay replacement original shock ...

lol good luck with that jh ....giggles

GAHHHHHH.

So, after working perfectly for one brief ride, stopping for petrol, starting again, and getting me smoothly into work, it wouldn't start after work. Then it did start, so I though it was just feeling a bit cold, then it stalled on me while rounding a corner in the parking garage, which was briefly entertaining. I checked the breather hose, adjusting the bottom clamp, and it started again.

It ran for long enough for me to get my jacket and helmet back on, then stalled and wouldn't start. Yes, I double-checked the plug leads when I put them on.

At this point, it's sitting in a secure garage at work and I am tempted to have a chat to the BM Shop at Stafford and get them to take it and fix it. I was preparing for a major bit of paid work including a new fuel pump anyway, so they may as well start the process, with pump. I just hope they can do it quickly. Preferrably, starting Monday.

*Grumble*

dang it jh .. good luck hope its not all bad news ....btw ,,,many have sought out different alternatives to the "stock" and expensive fuel pump ...

Well, I just couldn't leave it alone, of course. After more reading, I took tools in tonight to work, where it's still sitting while I wait to hear back from the BM shop, resolving to test the resistance of the coils. I also took one of the old, slightly used spark plugs and used that to test each (new) lead and (old) coil.

Nice, big, fat, bluish spark from every single one. So that means I can assume the coils, Hall sensor and CDI computers are all good? Please?

Which leaves me with another vacuum leak, or fuel. And it's clearly getting some fuel because it can catch. The tank is full so I can't look for fuel returning, so I'll need some other way of checking flow there.

I think I'll take in degreaser tomorrow night, spray some around the breather hose area and see if it catches and tells me there's a different leak.

Fun, fun, fun.

first check that the fuse 6 is in good shape or replace it anyhow and that you hear the fi relay working ...might be a good idea to have a replacement anyhow ,,,a 4 pin type i think

make sure you have checked the connector to the fuel pump ....mine was a dismal afair to start with i had to crimp the female part of the connections to clamp the male parts properly not sure if yours is under the seat rhs area like mine ...85 model should be i guess ...(deoxIT) mate

another 1 meter piece of fuel hose cut in half for 2 x 1/2 meter sections would be a good thing to have jh ...you could also take a inline joiners with you as well ( maybe a barb type off those garden hose stuff )right internal size of corse um 8mm.

first extend the fuel lines by about 1/2 a meter so that you can control the fuel leakage (you have no stop return ball in the return line ) some vice grips could be handy to clamp the lines whilst your playing around

what you could do is 2 things

1> confirm that you are getting presure to the fuel rail by hitting the start button and then checking that you have presure build up.

2> if first test passes do the same with the return line

an other piece of 4 mm line would be good to use as a mouth sucking vacume creator to let it operate the presure regulator

or if it fails could be the fuel pump



good luck

This is starting to sound like hall sensor problems John. Running for a while and stops then won't start then goes well then stops again it is very symptommatic of a hall sensor. PM me your address and I will send a plate down, that way you can replace it and get a better idea. they aren't hard to do. If it is that I would then buy a new one as an old one is just as liable to turn up it's toes soon and I keep it as a backup.

K Freak wrote:If it is that I would then buy a new one.

Or replace the sensors, far much cheaper. Honeywell.

Inge K.

Inge K. wrote:
Or replace the sensors, far much cheaper. Honeywell.

Inge K.

For people in Australia: Jaycar - http://jaycar.com.au/productView.asp?ID=ZD1900&keywords=hall&form=KEYWORD.

$50 for both sensors, or $775 from munichmotorcycles.com.au? Hmmm, tricky one!

Well, then.

Thanks, Charlie, that's pretty much what I was planning on doing. I'm printing out Crazy Frog's diagnostic sheet and will see what I can get to with a multimeter in the time available - EFI computer, that sort of thing.

Since I was getting good spark of all four plugs but it wasn't starting, and since I know they can run perfectly well on three cylinders (girlfriend's bike had a blocked injector) I'm still leaning towards something that isn't specific to one cylinder - Maybe EFI computer, maybe a plug is loose, maybe the ground under the tank is bad. I'm also leaning away from the Hall sensor being a problem for the same reason, but thanks very much K Freak, I sent you a message.

What I'm actually hoping for is that it's the pump, which I was about to get replaced anyway. That would be convenient

Put this one in the "hopeful" bag: Had enough time to test the coils before work - 1/4 is about 13k and 3 ohms - good enough to bang on. The 2/3 coil is about 10k and 3 ohms.

Both coils are getting 12V from the battery.

Second data point: If I leave the ignition on for a few minutes, the bike starts for a up to a minute or two. Charge building up?

Will continue testing, but I'm crossing my fingers I've found it. Now: To track down cheap coils ...

(Oh yes - all the injectors have a coil resistance of about 17 ohms, which is good).

still sounds like fuel presure to me jh ......those coils are reading ok ...and i dont think that that is your issue ......hmm even more info ....have you changed the fuel filter at all ....we have seen gummed up fuel filters in here ...that hold presure at zero revs ....but not quantity of flow ...cheep option as well ...all things concidered



hope you did the tank fuel cable connector fix .....

Haven't had time yet to look at fuel pressure, Charlie - I'm working in one hour blocks before and after work until I either hear from the mechanics, or give up and get it towed back to my place. I think I'll be getting it towed home, at this point.

I did the filter a month or so ago with the rest of a service and it's been fine in daily usage since (which doesn't mean it's fine now, of course).

Opinions seem to differ on whether a drop to 10k Ohms on the coil is meaningful - I've seem comments that it's way too low to produce a usable spark. Hmm. Luckily, we have an almost identical bike I can borrow a coil off to test. Maybe tomorrow.

I went from auto shop to auto shop this afternoon picking up a few things I needed and none of them stocked a pressure gauge I could use to actually measure fuel pressure. I'll be checking that fuel is pumping all the way around, at least.

I had considered the FI relay - should have written down the part number this afternoon before leaving the house.

Which connector to the pump are you referring to? The only one I'm familiar with is the plug under the tank, between the inlet and outlet fuel hoses.

yes you have the early pump connection if its placed there....

already replaced the filter ? ,,i saw that some one took it out and blew back the reverse to flow ...to clean up the gunk inside ....with positive results ....

worth doing at least before replacing the pump outright ...i saw that a few have used the peugeau pump at really cheep replacement prices (second hand i expect )

You know the worst thing, the absolute worst thing about this problem?

The bike is stuck at work and I can only work on it in half-hour or one-hour increments, and can't take it apart properly or leave stuff scattered about.

Since the BM Shop doesn't seem to be calling me back, I think I'll get it trailered home where I can devote a day to it.

Anyway, frustrated bitching aside:

It's not the coils. I pulled one off my girlfriend's bike (they both 11.5k Ohms between the high voltage terminals, but it's always started first time with barely any idle adjust, even in winter) - no improvement.

Plus, the symptoms are different! It will now start, run perfectly happily for 30 seconds to a couple of minutes, then stumble and die. It's not a starting problem, it's a running at idle problem.

So: Coils seem to work with a resistance between the high voltage terminals of 10.5k Ohms. Cautiously file that one away for future reference.

Next up:

Check all the intake air hoses and the air filter.

Drain the tank (I filled it on the way to work the night it died) and check the fuel filter.

Check the Hall sensor, when K Freak's spare gets here (thank you, once again!)

Oh, and: On Friday, when I have the day off - arrange for it to be trailered home.

On the other hand, the new battery is lasting fantastically well.

its a nice feeling huh jh? (battery being good ) just hope it doesnt go low enough to weld the starter contacts ...slow charger available jh ?.....start looking for fuel pump is my prediction ....although i havent had a look at your style of under tank connection (fuel pump power supply) might be worth having a dig in around there ol mate . make sure all the contacts are well and trully connected .....you could test this by attempting a start whilst measuring the terminals on top of the fuel pump itself (a couple of aligator type clip leads to get the meter probes out of the tank would be verry adviseable) ....look for anything below about 10.5 -11 volts whilst the pump is tying to do its thing.....given that the battery volts are still in the 12 or so volts area .

just a suggestion hope it helps

Okay, after testing things at work, finally getting it towed home, waiting a couple of days of socialising and bad weather and hangover until I can look at it, I am ready to make my second pronouncement:

FUEL PRESSURE REGULATOR.

A pressure gauge connected directly to the pump will show ~60psi before the pump cuts off (it's a compression tester with some modifications, so it goes to 300psi and isn't very finely calibrated).

A pressure gauge connected to the back of the fuel rail will show ~50psi before the pump cuts off.

A pressure gauge connected anywhere inline to the fuel system, letting the bike run, will show no detectable pressure at all.

All other symptoms - will or won't run for 30 seconds, temperature may or may not make a difference - can probably be explained by: "Dying, but not entirely dead yet, it just looks that way."

In addition, one extra thought: It has always needed more priming before starting than my girlfriend's bike - it has always seemed to bleed pressure out of the system faster, and that includes after the other bike has sat for a month without being ridden. This may have been getting worse lately, but that may just have been my imagination because everything else has been getting steadily better while I've worked on it.

Now, your mission, if you choose to accept it, is explain why it might be something else.

crikey ....im confused jh ......yes after hitting the start button the rail should build up presure .....when vacuum is applied to the triger of the fuel presure regulator it should regulate at 32-36 psi ....if you measure the fuel return line it should be nearly nothing ...but still something ..as the only presure it should have is the balence of the fuel in the tank to get over ....so under 14 psi .. if your return ball valve is stuck all sorts of things might happen ...but not likely .

would it be an idea to get a longer tube that sits outside the return rail return to the tank and let it (connected at the fuel presure regulator output ) and see what its doing ? do you have vacuume at all getting to the fpr ? if it doesnt start ...im afraid this maybe so .maybe a additional 4mm pipe could be used to see if the frp opens when you suck on it ?



as in the words of someone we loved to cringe at ..."please explain "?

just thought ...if you have 50 odd psi on the return line to the tank ....it kinda sounds like your breather tube is well and trully blocked (exits from under the tank ....is it folded over ..? have you tried with the cap off ?)

Okay, I may have confused everyone (well, charlie99, but I'll take him as a proxy for "everyone").

I connected a pressure gauge to the back of the fuel line directly, so that the gauge blocked the line. This was to check fuel was getting that far at least. So that tripped the pump cutoff so fuel wasn't getting anywhere (also, with everything connected normally fuel can be clearly seen bubbling back into the tank when the pump is running, so yes, the system is unblocked.)

Then I spliced the gauge in between the end of the rail and the FPR, so the fuel system is uninterrupted but I was checking pressure essentially at the injectors, and the bike could not build up enough pressure in the lines to start. So, I concluded that the FPR was just stuck open and fuel was going straight through, back to the tank, without building up pressure.

So: The pump can deliver 64psi, but the FPR does not seem to be holding 32 in the lines, and the only pressure is whatever's required to send petrol through an 8mm gap, back to where it started!

um ...replace the fpr ? it should be holding it

That's what I was going for, I was just waiting half a day to see if anyone could give me a compelling reason not to spend nearly $300! (Edit: I would buy from overseas, but at this point I'll pay the extra locally to get it on the road faster).

I really, seriously can not conceive of any reason why it could not be the FPR at this point, but I'm wary of assuming anything on a comlicated beastie like a K!

$300 crikey ...its just a vacuume accuated , sping loaded diaphram type valve ....is this chris (bmshop ) price ...or a real one



moto bins list one for 44 pounds (plus delivery ) that could be um under a hundred and 6- 8 days max



maybe even give twb a call at "whiteline bmw" and get a quote huh ?

Well, $220 from Munichmotorcycles. I get to get this resolved sharpish - Imbil rally in mid November, and both bikes need to be trustworthy by then. Also, we're a bit low on reliable vehicles at the moment, and a taxi fare home from work is $60.

I'm not going to help here , but it could be the pump as well. It has a relief valve that could be stuck open (specially after you had it run against a closed line).
If you have a bicycle pump with a gauge you could connect it to the line into the FPR (aft end of the fuel rail) and see at what pressure the valve opens.
The vacuum line has no relevance for this, it is just a 'fine adjustment' for the pressure once the bike is running but doesn't affect the base setting. Remember that the 1100 doesn't have the vacuum line. These parts have been used in lots of (car-) engines, so a second hand should be readily available. New ones go for 50-70 GBP.

Actually, ReneZ, that sort of input is exactly what I was hoping for!

The behaviour has now been consistent enough for me to think the relief valve in the pump is not the issue, but what the hell, it could be!

I hadn't thought of that bicycle pump idea, that's a good one, thank you. Don't currently have one with a gauge but we've been meaning to get another car foot pump for so long I may as well do that - they're only $20 or so, and that's an easy and quick check.

Doh !!! silly me for phrasing it like that ......should have said vacume assisted .....yes indeed there are lots of cars out there that run almost the same presures and a more homley version might be obtainable really quick and far cheaper .

great update rene....

Should be much cheaper at a car parts store, or Bosch workshop/part store
(if you got those ones down under?).

Bosch # 0 280 160 200.

Search a crossreference list to find exact similar products from other manufacturers, is another possibility.

Inge K.

Well, for final confirmation: Hooking a bicycle pump up to the FPR results in the return valve in the tank cycling with merely one pump. That's not even pressure I can detect in the pump, let alone on a gauge.

Anyway: Pricing of parts? Expletive. Really quite a lot of expletives. From, get this lovely name for you non-Australians, "Supercheap Auto" it is $240. It's only $220 from http://munichmotorcycles.com.au and, as charlie99 pointed out, just under $70 Australian plus postage from the UK.

Someone (guess who) has to pay the 5mil that the Bathurst race costs them, so I heard.

Plus there is the probably 15mil that it costs to run a team of V8 supercars

Great you found it. Now realise that many car systems were equiped with the same FPR. Saab, Jaguar, all others that had a Bosch Jetronic fitted. They don't go duff that often, so have a look around. Then again if you like new (and bling) go for it ;-)

Hello again.

Well, I finally sorted it and got it running again.

I got the new FPR, pulled the other one off, found that I could blow through it with no resistance at all so the pressure diaphram/spring was completely shot, checked the new one, installed it ... Still not starting, but the symptoms had changed again!

I went over the entire bike with a multimeter again and found that all the values were within reasonable, previously found, pretty good ranges.

Only one thing to do, then ...

I pulled the spare EFI module out of my girlfriend's bike, plugged it in, start first go, idle sweetly ...

It's never just one thing, is it?

So my undying gratitude to Crazy Frog for collating the EFI trouble-shooting sheet and to BMW for making it so incredibly easy to work on compared to some other bikes I could mention.

I am also rethinking my position vis-a-vis preferring fuel injection over carburetors.

Of course, it's entirely possible I burnt out the EFI by repeated attempts at starting while trouble-shooting, which is a worrying thought ...

Added note:

A long time ago, my girlfriend had a boyfriend with a Kawasaki B1. She remembers him going through about four computers, because they kept burning out.

Spare me!

I very rarely hear of an ECU dropping it's bundle they have proven over the years to be reliable.

Far more common to fry a CDI unit and of course finding one is a bit harder.

If you were refering to the Z1300B1 they had a habit of cooking the ECU. They were very similar to the BMW ones and made by Bosch. Some of the Z1000s were similar and didn't have much trouble, I don't know if the problem was solved but the next model had a very different unit and isn't interchangeable.

I have been considering putting two K75 units on my Z1300 and running them in tandem. Be an interesting project.

dang huh ! jh ......didnt i hear that bean bought one from someone up here just recently .. between you and me ...after firring it up and cleaning out all the gunk .....might be worth a re-try with the original ?

you never know just the fact of unplugging and reconnecting might have cleared the issue ....worth a try at least ....just make sure you have left it off for at least over night ...sometimes the computer bits get stuck on a logic high and need time to settle back to normal levels with a good discharge ....

Finally, I have a running bike again.

This makes me very, very happy.

Old unit wasn't going to cooperate, even after resting. Replacement plugged in, bike has now started several times and, more importantly, stayed running for three trips.

Now I just have to get a new front tyre next week, and pay the rego. Fun times.

Good news at the end but as you say who would figure on two significant problems. Your persistence paid off though good on you!
Regards,
K-BIKE