I now have a rebuilt starter new fuel lines, new computer, new spark plugs, new FPR, new intake manifold rubbers, new battery, and the darn bike is now doing the same thing that caused me to start this thread, oh yeah, new vacuum lines. I got about four hundred miles out of it before all this started again. The difference this time is I noticed when it is running the low fuel light, my bike has a yellow light and a red light, not sure what the yellow light is for, it has never worked and the red light has remained lit the entire time I have owned this bike, but it now brightens and dims as I increased or decrease throttle, it seems I recall that happeneing just before it failed the first time. Is there some switching or relay, or something that is effected by those indicators? To clarify, the bike is turning over and fuel is flowing into the cylinders and of course flooding but it is not firing, unless I unplug the electrical connector on the fuel tank. It starts and throttles with that connector unplugged but as soon as you plug it back in the engine stalls.






I've been throught the checklist of things to check out, found here, i forget which thread. I checked the coils, I bought a known working ECU, I replaced the FPR, New plugs, new plug wires etc, etc. I saw a thread on this forum on exactly the same problem but I did not ever see where anyone had actually stated what the problem was in the end. Can anyone give me a clue where to go next. I've been riding this bike all this country for a decade and never had any problems, now this.
  Bike floods when trying to start it, and it won't run. Ive had to empty the oil and remove the oil filter three times as the crank case fills up with fuel when attempting to start it. I found this post:

https://www.k100-forum.com/t2062-bike-will-not-start-flooding-1984-k100rt

A little way down in the thread there is a checklist:

Problem:

Bike will not start
after having been down, once in a while a backfire. Continued
starting will result in fuel in the exhaust. On occasion it sounds as
if she will pick up, but dies again. This whilst playing with the
throttle a bit. We had her running for some time on Sunday, but the
next day it was same old.....

What we have done:

Check battery voltage -
OK

Check injector pulse
with LED – OK

Check loom between
injectors and ECU – OK

Check injector
resistance – OK (16 Ohm)

Check injectors outside
of engine – OK (bit of doubt about the amount, but they all
'squirt' – OK

Check fuel pressure –
OK (after change of pump and fuel pressure regulator)

Check fuel hoses – OK
(part renewed)

Check fuel return to
tank - OK

Check coils – OK
(Prim 2.5, sec 12.5K)

Check FI computer –
OK (replaced with known good part, same issues remain)

Check the spark plugs –
OK (the 'tell-tale light' blinks)

Check the AMM – OK
(Flap moves, electrically measured and is OK)

Check connection
between AMM and plenum – OK

Check cooling water
temp sensor – OK (2.5K at 20C)

Cleaned all connectors
in sight

Still to do:

Check compression,
however bike has ran OK

Measure amps during
starting


Ceremonially burn the
bike!

On completion:

Oil
change

Anything we might have missed? Thanks!


Last edited by ReneZ on Tue Apr 12, 2011 2:38 pm; edited 1 time in total (Reason for editing : Strange formatting text)

I have been through all of these items and still have not been able to get my bike to start or run. It turns over and over and occaisionally will fire but if I turn the throttle it dies instantly. The motorcycle now has :

New fuel pressure regulator, new ECU, Tested the coils, as far as I can see they are fucntioning as they should, all new vacuum hoses, all new fuel hoses, etc. I'm an electrician by trade so I have the neccessary meters. I just am not seeing what else I could be missing.
 As for all the little connectors, I have made a habit of regularly checking and cleaning them as a couple years ago I stalled the bike in southeast Colorado, essentially a desert, in 100 degree heat middle of the day because of corrosion on connectors. Expensive Tow, long wait for a ride, lesson learned. I'm just stumped

Probably best to put a bit up about the problem and what has already been done

6strings wrote:Ive had to empty the oil and remove the oil filter three times as the crank case fills up with fuel when attempting to start it.

Do a compression test. Fuel in the oil sounds very much like stuck or worn rings.

It's my party piece, but, don't see a new fuel filter on that list?
Don't ask why this is always my first thought, except it was more like 45F than a 100 at the time. 
You say you've checked the plugs, that's a nice juicy spark from a plug sitting on the cylinder head?
Don't worry, someone will come with the answer. They love a challenge.

Crank case filling up with fuel suggest an injector problem to me. Flooding wouldn't normally put so much fuel into the crank case that would require a sump drain. Recheck the hose routing connections to make sure you are not putting fuel pump pressure onto the injector rail, not sure how injectors would cope with that but it would pump a lot of gas........

My only other thought is a valve/camshaft/rings problem and compression test will tell you more.

busted diaphragm on the fuel pressure regulator ....then feeding back the vacuum line into cylinder 4 ?
just a wild guess

although with this one I would expect the exhaust to flood as well

That doesn't sound so wild. I wondered could pipes be wrong way round sending the full pressure to the fuel rail but the diaphragm makes a lot of sense with the quantity of petrol in the oil. The petrol in the oil points away from the usual suspect list of electrical items.

would be pretty easy to test the theory ...just pull the vacuum line and see if fuel flows out it on start

Sorry guys, the flooded crank case was caused by me trying to start it over and over and over.  Once I cleaned everything up the second time, is when I found this Forum and began looking at all these things. And yes now If I turn it over it does begin to leak from one of the exhaust manifolds. I have taken out the fuel rail and injectors they seem to squirt right, not sure I'm no expert. They don't seem to be stuck open though. I'm starting to think maybe the coils. I saw somewhere in this forum about them not firing 'hot' enough, or not enough voltage. I can hear the fuel pump working, and can see the injectors squirting, that to me means the thing is sending those signals correctly. and yes I have replaced every single hose and fuel line, one at a time so as to not mix them up and route them wrong. I also put on a brand new fuel pressure regulator. At this point I may purchase a set of coils, it can't hurt, I've replaced everthing else.

This old bike has been to every state on this continent and Canada, I sure would like her to keep running, I have a k100rs, they were purchased from the dealer the same day in 1986, I bought them from the original owner as a pair. Just trying to keep the RS stock, I believe that body style will be the 'classic' one day.

I would say that a sump full of fuel is symptomatic of leaking injectors.
Pull the injector rail off with the injectors still attached, block the outlet on the rear end and leave them hanging over night and see if they dribble. Also check that the FPR is not leaking by using Charlie's method. You say you replaced the FPR, was it a new item. Old unused FPR has a far higher chance of leaking than a continuously used old one.

I bought a new FPR, on Amazon, of all places, but still OEM bosch piece.

That should rule out the FPR being the problem  so check out the injectors for leaking. Even without the pump running there will be some pressure due to the tank being higher. This may not be the original problem but does need to be addressed because one day you may try to start it with a cylinder of fuel and damage the engine.

Just took the fuel rail out and turned the bike over, the injectors are spraying intermittently as they should be. I wonder just how much 'in volume' they should spray, as the amount of fuel being projected from these seems excessive.

They should have a very fine mist, if you hold a piece of dark cardboard in front of the nozzle it should show as a dark patch after 4 - 5 sprays and be a circular pattern. If you get droplets or squirts then they need servicing or maybe even replacing

Maybe leaking injectors but you say...

Check injectors outside
of engine – OK (bit of doubt about the amount, but they all
'squirt' – OK

From your description of how the injectors operate, they are all squirting and pulsing. I don't see how all would start leaking and I don't think one leaking injector would flood the exhaust and crankcase to that degree. Maybe if one was stuck open?? and you'd probably notice that. Rick's suggestion will certainly clear that up but if the injectors are squirting excessively it can only mean too much pressure or they're stuck open.

I had a close look at the photo you posted in the previous thread and the fuel hoses appear to be routed correctly. but obviously can't see the FPR... unless this is an old photo and you've done work since??

Fuel in the exhaust and sump would indicate excessive fuel delivery to me. Are you sure you bought the correct FPR. You got a number for it? You sure its hooked up right. R-series FPRs are 3bar for example. I'd test with a pressure guage.
When you tested them out of the head, did they stop squirting when you stopped cranking?


Incorrect fuel line routing could certainly cause excessive fuel.

You said it was running for a while. How well did it run?

How long are you cranking it over each time?

Check the HT leads are hooked up in the correct order.

Just my thoughts. Hope you get it sorted.

I bought the OEM fuel pressure regulator for this bike, 1985 k100rt, I don't have a pressure gauge to check it. Maybe should get one. I was just thinking, about four years ago I had to replace the fuel pump and I used an alternate, I think from some small ford vehicle. I found that info somewhere online and new a guy that was using that fuel pump. But it worked great for these years since installing it. Note, I don't know what the flow should look like when the injectors are squirting, but from what i'm seeing, they are releasing about, just a guess, didn't put a measuring device up to it, but maybe 10 or 15 mL per injector, per 'squirt'. Funny, I've never worked on the fuel system before, always electrical issues, just a K bike thing. Change oil, check the spark plugs and go for a ride. Last evening  did notice that the fuel lines seem to "puff up" or expand, quite a bit, I don't recall seeing that before I changed the fuel lines, Maybe to big?

Thank you, Rick, that is exactly what was thinking, mine are pouring not spray or mist. They completely drenched the piece of card stock I put under them. I'm now off to find some injectors. Any thoughts on the re-manufactured injectors on ebay with the four nozzles?

!5ml is a lot of fuel to let go in one hit. They should deliver 155ml/ minute at 36psi, that is open for a full minute and at full throttle they open for about 450micro seconds which is just under 1/2 milli second and that equates to 0.075 ml for each opening. Like I said it is a fine mist that takes a few squirts to even wet a surface.

That's exactly what I thought, just not a mechanic so wasn't sure. This forum is awesome, I've been fixing this bike by trial and error for years, The local BMW dealership won't even look at an old K-bike, they're funny that way.

Injectors are fine. They can't open any more than what they're designed to. You've got excess fuel pressure.
There's only 2 reasons that would happen
- Faulty/incorrect FPR
- Incorrectly connected/routed fuel lines

Throw up a part number for your FPR and a pic of the fuel lines. I couldn't find any K100 FPR on Amazon so not sure what you bought there.
OK. Found that
The BMW part no is 13531460451
The Bosch oem is 0 280 160 200

You said in post#16 "the fuel lines seem to "puff up" or expand, quite a bit"... Is this when the pump goes on or they just look that way normally? If they're not handling the pressure you need to address this asap as it's a potential catastrophe

crikey a lot of fuel indeed

I wonder if the fpr is reverse plumbed ?  just a thought

For what its worth I decided when I was replacing fuel lines to stay with the BMW pipe. Its an 8 x 13mm but at least its the right one and not expensive. I even keep a length inside the pannier lid where it lives out of the way. All the black fuel lines are pressurised, some at the fuel pump pressure [much higher] and some at the FPR pressure 36psi..
 
There is no way that pipe would expand under pressure so I am thinking if you use an incorrect one could it cause the FPR to end up 'confused' and pump higher pressure. I would think recheck that fuel pipe first to make sure its the correct rating and be fully sure its the correct routing and no kinks anywhere.

I don't have the part nos but some of the parts that look similar are not and I wonder is it the right FPR too. I still am concerned the fuel lines are routed correctly.

Anyone an answer for this: Does the FPR have an electrical connection and what happens if its not connected/faulty?

If your fuel lines are visibly expanding with the pressure then you have the wrong type of line. You need fuel line that is rated for fuel injection.
There is no electrical connection on the FPR.

I just got the correct "fuel injection" high pressure fuel lines. Waiting for new injectors, checked on the FPR number and I did in fact get the correct FPR. So wait for new injectors and install the new fuel lines, and check in with you all later. I appreciate all the feedback.  Motorcycle people around here look at this bike like it just landed from another planet, this is Harley country after all.

6strings wrote: I'm now off to find some injectors. Any thoughts on the re-manufactured injectors on ebay with the four nozzles?

If they are the green ones from the States that are touted as an 'upgrade' for the K, they are the #0280150415 and while these will work fine, by my calculation they will run a bit lean. They are not designed for the K engine or to work efficiently with the K 2V inlet manifold.
Lots of posts here about injectors.
IMO you'd be better off saving your money and stick with the ones you've got. They're working ok and have had a bit of a pressure clean . Its the fuel pressure you need to worry about... before you install the new lines.

I've been thinking on the pressure thing. I know absolutely, the FPR I purchased is correct, I researched it extensively, buying online has cost me alot of return postage. If the fuel lines are expanding I can imagine the fuel pressure regulator would be able to deliver a consistent pressure. With that in mind I also began to think about the tubing lengths. I was not careful to replicate lengths. My shop rat dutifully cleaned up the shop and swept the floors yesterday so all the old parts are probably in the landfill somewhere. I don't suppose anyone here would happen to have those measurements. Also The tubing I purchased maybe kinking as it is not preformed for the K. I don't know that it is kinked as you can't really see behind the airbox readily. But it would seem to me that the expansion and possible length difference may cause the FPR some difficulty. As for the injectors I still have the originals and will definitely reinstall them. Those green one are so cheap I'm sure I can find some body with a Ford truck that can use them. I have an Auto mechanic in the shop bay next to mine. I'm still concerned with how much they actually release, they do not produce a mist at all just a steady stream

What's the number on the side of your old injectors? You may have the wrong ones... but they were working ok before...??

Hose lengths (to a point) will not matter, how they are routed and connected will.
This will show how it's supposed to be hooked up
https://www.k100-forum.com/t6037-hose-replacement#68571

6strings wrote:I've been thinking on the pressure thing. I know absolutely, the FPR I purchased is correct, I researched it extensively, buying online has cost me alot of return postage. If the fuel lines are expanding I can imagine the fuel pressure regulator would be able to deliver a consistent pressure. With that in mind I also began to think about the tubing lengths. I was not careful to replicate lengths. My shop rat dutifully cleaned up the shop and swept the floors yesterday so all the old parts are probably in the landfill somewhere. I don't suppose anyone here would happen to have those measurements. Also The tubing I purchased maybe kinking as it is not preformed for the K. I don't know that it is kinked as you can't really see behind the airbox readily. But it would seem to me that the expansion and possible length difference may cause the FPR some difficulty. As for the injectors I still have the originals and will definitely reinstall them. Those green one are so cheap I'm sure I can find some body with a Ford truck that can use them. I have an Auto mechanic in the shop bay next to mine. I'm still concerned with how much they actually release, they do not produce a mist at all just a steady stream

A few years back when I had a problem I had an idea to extend the fuel pipes on the K, as in replace the old ones with slightly longer ones. I did this and many others on the forum have done it without any problems. It allows you to move the tank sufficiently to access the radiator cap, the relay box and some connectors under the tank without having to disconnect the fuel lines. Even last night talking to 88KE he was commenting on how it works so well. Definitely the length wont be the cause of a problem.

My knowledge of mechanical engineering and hydraulics is more limited but it does suggest that the priority is to change the fuel pipe to the correct one if its not the right one. There is a valid argument for the pipe being the source of the problem if its actually bulging under pressure. I know you are confident on the routing but something is not right and it may be the new FPR is a dud. Its logical, working backwards from the last task. I just find it hard to take in all 4 injectors failing at the one time with an identical issue when all was working fine before.

That's turning the engine over with the starter, rail still attached, but just removed from the injector ports. I just finished installing the correct fuel line type and checking for kinks in the vacuum hoses, I was concerned about the vacuum line to the FPR, as it is not the preformed type that was on the bike but generic vacuum hose I got at the auto parts store. didn't appear to be kinked but I don't know how actual bend the hose can handle without starting to close the opening too much. When I had the rail out and was turning the bike over checking the fuel flow, the bike started and ran until the excess fuel in the cylinders burned off. I'm beginning to be confused again. Maybe the coils are firing but not hot enough. I put D7EA plugs into it. That was at the beginning of this episode, as the bike had just started acting like this that day. I just thought plugs, as they were 9 years old, but new plugs didn't help, hence, this posting frenzy. I have another known woring computer arriving Friday, although i'm certain that is not the problem. At this point I think coils might be the thing to check out. I am absolutely certain on the hose placement, as I took them off and replaced them one at a time. At no point did I have more than one tube off at a time. no chance of mixing up those, I did this intentionally with this in mind. There is a thread here somewhere, where someone mention that the coils checked out as not shorted and sending spark, but it turned out the spark was of less voltage than neccessary, in other words, not hot enough. that would explain the sudden nature of the bike's failure. The coils are similar to transformer coils and when a transformer fails very often it's one minute on, next minute shorted or simply burned through somewhere in the windings, decreasing the output. That's why you'll often see street lights switching on and off, the capacitor will start the lamp but the damaged transformer, aka ballast, cannot support the load. I was looking for that post as I believe I saw the actual K ohms a good coil should read. Of course now I don't know where it was.

Ah hah! just found the thread on coil readings, check that tomorrow

http://hrsbstaff.ednet.ns.ca/bvogel/K100/download/bike-wont-start1.htm

don't forget that with that much fuel getting into the cylinders that it will foul plugs up pretty quick

might be an idea to have 2 sets available ,,,,one cleaned and good ...ready to swap into the head as you make changes ?

I double checked my coils with two other meters just to make sure. I am in fact getting 12 to 13 ohms.
But now a new turn of events. I unplugged the electrical connector to the fuel tank, the bike started right up and sounded good until the backed up fuel ran out. So I let the fuel pump run a second or two and unplugged the connector again and the bike started up. is it possible to have a fuel pump gone rogue, so to speak, my experience is that the pump might stall once or twice and then start and run for a while and then just crap out completely. My second one did it on a lonely road in Wyoming. I'm thinking of trying to find mechanic. I'm kind of out of my pay grade already.

It is very possible, I have had two pumps behave like that just prior to dying.

Didn't someone have a stuck fuel return check valve once that was causing a similar problem?

Link to stuck valve: Stuck return valve  also: Another stuck return valve

yes I remember that too

perhaps a search might find it again

good pickup technoid

The fact that the motor runs with just the residual fuel says the electrics are ok. The problem is the fuel supply.
If the safety valve on the pump is stuck, that would cause excess fuel but I'm sure the FPR would handle that unless maybe it was really excessive. I think I read somewhere that the pump can produce around 100psi when it kicks in. Not sure if that's correct, but if the release valve is stuck then that would explain the bulging fuel lines and fuel filling the sump etc. But for me, it seems more likely to be the FPR. Try taking the return line off the tank and stick it into a bottle. Press the starter and see if you get fuel.

I'm going to try that right now. That's the reason I replaced the regulator, because wasn't letting anything through, I tried starting the bike, it flooded and I took that line off and it was dry, so I replaced the FPR. But obviously that didn't get the bike to run. That was about the time I started this posting. I'm also going to double check the vacuum system. I just ordered the p74095 ford fuel pump next day air so should get it Tuesday. I noticed last evening that it seems to run on after I let off of the starter button, and makes a sort of squeeky sound when it pulses, I don't recall ever hearing that in the past. The pump that's in it is the p74095 and it's been in there since 2009, with no problems. I don't know how long a fuel pump should last, but I don't recall ever hearing it before these last few days.

I was checking the vacuum lines, and had the air box out. I turned the engine over and happened to look at the base of the throttle bodies, they are 'blowing bubbles' you could visibly see  air moving in and out through the gunk and build up on the rubber gaskets or whatever they are called, don't think the parts store is going to have anything like that, and at thirty years old even new old stock is likely to be crispy. Okay found a whole throttle body set with the manifold rubbers, $65.00 US. They are refurbished the rubbers look new so I guess I'll have a spare set of throttle bodies. They're nice and shiny, so may just install them as a whole and remove my old ones that are grimey and corroded. I got them from a BMW dealer on ebay, I think it was boxerworks. So wait another week for another part, bummer the season is getting away.

Oh yeah forgot to elaborate. I saw a crack on the air box side of the manifolds, so I went to the other side and swabbed off the grime on the rail side and sure enough the manifold on cylinder number one is cracked almost all the way round, Gotta think that would definitely cause a lot of problems for the fuel/ air system. Having damn near replaced everything in  the fuel system including the computer, and verifiying that I was getting fuel through the return. I have to think this is the problem. I know everybody is done reading my posts but I am grateful for someone elses in put as I have minimal mechanical, or diagnostic skills, I'm learning, crash course style, but I'm learning. Thanks folks!

sounds like a good find


for resolving some issues at least

go for it

So I went to the auto parts store and bought some gasoline rated RTV silicone gasket sealer. I then picked up some of those long wooden swabs like the doctor use. I went back to the shop grabbed abucket to sit one and painted that gunk over all the air intake manifolds. I let it set up for an hour or so. then turned the bike over. It started right up, I put 40 miles on it today, just around town, didnt want to get too far out in case of failure. So I have new manifolds on the way and know what was wrong with the dang thing. Go figure

Feels good, doesn't it!  You're on your way to being your bike's master.

Good news. Nice fix with the silicon. Handy to know.

I use this self fusing silicone tape at work for taping the rigging on boats, insulating wires, and patching hoses.  It should work pretty well for sealing leaky throttle bushings and vacuum lines.  It's good to 500F and it's UV, water and solvent proof.  Never thought to use it on my bike, but now I think I'll get a roll to carry in my tool kit.

http://www.ebay.com/itm/Vypar-Products-TPE-XCSB-1x10ft-Black-X-Treme-Self-Fusing-Silicon-Rubber-Tape-/201306184385?pt=LH_DefaultDomain_0&hash=item2edec89ac1

I would say it is a 'get you home from the trip your on' solution, if your manifolds happen to give out. I ordered a new set but I think I might ride around with the old silicone coated ones for a while to see what happens. An god knows if it was just that that was the problem. I changed almost everything in the fuel system and all the vacuum lines, but it wouldn't run until after I discovered the cracks in the manifolds. I've heard often, if the K doesn't run right look for air leaks, I just wasn't looking in the right place, I guess. So now I know. This forum is great as well, I received alot of useful info and in the process learned one hundred percent more about my machine than I knew before I came here. The crowd here is awesome and I am thankful for all your input.

I think you're right about a 'get you home from the trip your on' solution. I wouldn't be riding it around too much. If a small piece of that silicon dislodges, it could do some damage.

I'm probaly talking to  myself by now in this thread, but, I got my new manifolds today, so tomorrow I attempt to install them. It looks fairly straight forward as I have had the fuel rail off and the injectors out already. Oh, and just for giggles I put those four nozzle injectors in to test them out. The engine isn't quit as spunky as normal but it seems, well smoother, is the only way I could describe it, seems like a little less power as well. I'll put the originals back in tomorrow when I have the throttle bodies out.

still watching ...
lets see what  tomorrow does

good luck

New throttle body manifolds are installed. Bike ran great. As for the injectors I can't really tell much difference. I was riding around town yesterday and the dang starter crapped out, got a new one on the way, so just another wait for parts. Honestly was expecting the starter to give. The contacts on it are seriously thin. The first time I took it out I used 1000 grit sand paper to clean the contacts and it's been eating brushes ever since. I know, stupid, but at the time I didn't know better, someone told me to clean the contacts and I did. Another lesson learned the hard way. That was in July 2008.