To make a long story short. My Bike ran good all last year until I began riding this season, long about April. Started to run erratic so I changed the fuel filter which was original ( the bike has 9600 miles), to no avail. Sputtering and smoking black. Checked fuel pressure 36psi. Replaced fuel with fresh still no luck! Read this forum for hints and found Bert's stuff. Checked and replaced hall sensors...stil no good checked and replaced water temp sensor... NOT! Checked all connections,grounds and hots replaced battery and had alt checked still ran bad and sometimes not at all. Checked ignition switch tested spark plug leads which showed infinite resistance but had good spark thru them. Replaced plugs and repaired a bad vacuum leak at the throttle body. Ran with the tps unplugged and still this thing is not running I am to the point where it started and shut off as if the ignition switch was turned off. Floods the engine terribly. I unhooked the return line to the tank and did manage to get it to run a while longer but plugs are fouled now. I was thinking fuel pressure but it checked ok. Checked resistance values as described in Bert's pub for the MAF which is as follows pins 7-5=108, 7-8=361, 8-5=363, 8-9=189@ 85deg F
I am extremely frustrated and do not want take to dealer! They seem to know less than you anyone or do not want to share info!
I seem to be overlooking something but cannot put my finger on it. It ran fine last season WTF HELP!!

I would check the regulator, sounds stuck on the return, it is situated rear of the fuel rail. Only wealthy people go to the agents. We will get you out of it here.
Cheers Ajays

Will check it out...Thanks

Have a good look if the ECU plug is properly fitted. It should 'click' in place. You could remove the fuelrail with injectors and see what happens when you press the starter. Normally the injectors are provided with 12V and the ECU switches ground. If for any reason the lead between the injectors and the ECU is shorted, the injectors will remain open continuously.

Infinite resistance on a K75 spark plug lead is correct they should have that as they have a spark gap in them by design unlike the K100.
Regards,
K-BIKE

Hi,

I'm experience the same problem with my '85 RT and still have no solution:

http://k100rt.aforumfree.com/electrical-f8/k100-starts-and-stalls-t1192.htm

Right now my bike is in our BMW dealership, but no result so far.

Interesting is that I changed ECU and ingnition control and still bike start and stalls, flooding the engine.

Hi Marko,
What is the actual fuel pressure you are measuring on your system at the injection rail. You will need a pressure gauge to measure it.
Regards,
K-BIKE

It's 32-36PSI - pretty near what it should be. I also replaced ECU, CDI, injectors, airflow metter, checked temp. sensors and run out of theories. All electric connections are ok.

Here in our BMW dealership are talking of some injection troubleshoot connector that they can use to diagnose the problem, but I don't thing this analog system has one.

Lets talk about the theory...

In order for the FI module to energize the injectors, it has to receive a signal from the ignition module.
The ignition module will send this signal only if it receives from the Hall sensors the information that the engine is rotating.

No signal from the Hall sensors = no ignition or fuel injection. This is to avoid to flood the engine if its not turning.

You had replaced both modules and one can assume that they are good.
What if you have a bad connection (or a lose conductor) between the ignition module and the coils?

In this scenario, the engine is rotating. The Hall sensors are sending the signal to the ignition module and the FI module receive the signal from the ignition. For the electronic, everything is OK except that the coils are intermittently missing a signal.

When you remove the spark plugs to check it, you may slightly move this wire and re-enable the connection until the vibration brakes it again.
The best thing would be to check the ignition without moving any wire.
Using an ignition strobe light would do the trick. You simply clip the inductive lead over the spark plug wire and monitor your ignition by watching the strobe flash.

second option, the ignition is OK and you disconnected the Throttle Position Switch.
The functions of the 2 switches built in the TPS are:
-Switch #1 is to signal that the throttle is close and the FI should shut down if the engine is running over 2000rpm
-Switch #2 signals full throttle and full load. It tells the EFI computer that the engine is on full load and the mixture air/fuel is enriched. This signal is a negative 12v (or ground)
What if you have a short on the wire between the TPS and the FI module? Removing the TPS would not change anything, and the injection would still get the signal that the engine is on full load resulting in an excess of fuel. As the throttle is close, not enough air would pass to balance the mixture fuel/air resulting in flooding.

Just throwing a couple of ideas.

Bert

Crazy Frog wrote:Lets talk about the theory...

Thanks Bert!

We used ignition strobe light in the dealership and found that until the last revolution of the engine there was a spark. I also checked the TPS and it is ok, after that I checked all cables that go to EFI module and ingnition module (including from the temp. sensor, TPS, airflow meter valve and so on.), and everything seems to be ok - there is no corrosion anywhere also.

There is one cable that comes from inside the engine, near the Hal sensors, I'm wondering what's that for?

Also in earlier models there is a fuel pressure switch on the throttle bodies that I'm not sure If this bike has, and what it does.

Other theory is that coils are not completely bad, but give spark weak enough to flood the engine...

Ivo Markov

Check the breather pipe that comes out of the crankcase and goes into the airbox for cracks . Have a good look at it on the inside of the bends. Check all the way out the front to the fuel pressure regulator(FPR) or whatever it's called (It's a canister behind the throttle bodies ). Check all the pipes for cracks and make sure their clips are tight. I'm not familier with your model but it will do no harm to check. I ride a K1 and had real problems with high fuel consumtion, fouled plugs, black smoke, and a sooty muffler end. Turned out to be split crankcase breather pipe and/or the pipe had come adrift from the FPR. I know our bikes have different airboxes but I think you will have similar pipework. Also, (and this is most important) on such an old bike, PULL APART and clean EVERY electrical contact, plug and earth and spray with a good electrical contact cleaner. Good Luck. Nick (Herefordshire, UK)

markovivo wrote:

Crazy Frog wrote:Lets talk about the theory...

There is one cable that comes from inside the engine, near the Hal sensors, I'm wondering what's that for?

I think you are referring to the oil pressure switch lead, which passes through the Hall Sensor cover area on its way from underneath the engine in the water/oil pump area to the indicator light or gauge on the dash. It's a single wire, and covered with a plastic sheath which makes it look a heavier gauge and thus, more important...

Hi Ivo,
Take a look at the pulses to the injectors. All injectors get an open and spray pulse at the same time so put a test light across one of the injectors to see what the pulses look like. I am wondering are you getting too many pulses compared to normal or are the injectors staying open longer. You would need to do the test on a similar bike to compare your flash rate and duration with the flash rate and duration of the other bike.
Last thought what compression pressure are you getting in all cylinders with bike turning over on the starter with wide open throttle.
Regards,
K-BIKE

Gotta call this a thread jack. 8675k needed help, but I'm thinking we've switched over to assisting markovivo. Granted 8675k hasn't been here in a bit, but we should probably try and keep things orderly. Further assistance to marko could be added to his existing (and noted) thread:

http://k100rt.aforumfree.com/electrical-f8/1986-k75c-runs-then-floods-the-fuel-system-and-dies-t1468.htm#10477

Going back to the problem of flooding, what is it that controls the fuel delivery to the cylinders? Hall sensors give the pulse to open/close, open duration must be controlled by engine temp (is it a richer mixture when cold, sort of like choke?) and air flow. Air flow would be a factor to maintain proper mixture. It would be unusual for all injectors to fail at once in a manner that caused them to overinject fuel. 8675k, did you pull the injectors and fuel rail off the head as a unit and turn the engine over to observe the fuel pulses? Make sure you are not letting fuel spray on the starter/alternator area, which has open sparks, and the potential to ignite the raw fuel spilled (ask me how I know). All the injectors will pulse at the same time, fyi.

Thanks for all the input guys, I repaced the crankcase vent tube and the bike ran better for a short time. Thought I had the fix!! To no avail it started acting the same way and now am back to square 1 with a flooded engine.
I just can't seem to pinpoint the problem.
How much voltage drop can the system stand before it begins to be an issue? I did notice my new battery cannot withstand a current draw even though it's static voltage reads 12.6v. Also waht is the sytem amperage requirements maybe my new battery is culprit or can it be the alternator?

What do you mean your battery cannot withstand a current draw? What voltage are you getting and at what current load are you getting that? Open circuit voltage on a battery which is to all intents and purposes dead can look fine, the moment any load comes on the voltage is gone down to 8 volts or less.
Regards,
K-BIKE

K-BIKE
If I pull a 100 amp load on the battery the voltage drops to less than 10 volts instantly!
I now have a flooded engine w/no start, but it does turn over.
It seems when I repace something the engine runs fine for a short time then begins to run rich and starts to blubber and miss!

With a bike battery which has not been fully charged I would not be surprised to see ~10 volts on a 100 amp load. So are you sure there are no air-leaks on any of the cylinders since if the thing was trying to compensate for that it would cause the others to get overwhelmed with fuel since whatever one gets they all get. What compression are you getting on all three cylinders with no spark plugs, the coils low tension side disconnected and wide open throttle?
Regards,
K-BIKE

I have discovered some thing after all this back and forth w/checks and double checks. The dead head fuel pressure from the pump pegs my gauge at over 100psi. Even though I was seeing 36psi when teed into the feed line to the fuel rail. Apparently the internal relief in the pump is stuck...Problem? I think so!

100psi
Yes, this is a problem as it should be 65psi.
Theoretically, the external pressure relief valve (on the back of the throttle body) should compensate for it. I may be too much input pressure and the valve cannot absorb this excess.
First look at the bottom of this page to confirm the plumbing when testing.
Second, Use this page to open your pump and check the internal relief valve.
At least, you are on the route of recovery. Don't you feel good about having found the problem on your bike? Just give yourself a big pat on the shoulder

It sure does CF...just need to get my hands on a pump! I suspected the pump from the onset but because I was reading 36 psi when checking FP teed into fuel feed I didn't feel the need to ck full psi at pump! I shoould have been a little more insightful when the fuel lines were vibrating violently when the engine was running poorly,
Thanks again you guys never give up!
I will post how I make out when I install another pump...Need to gather funds!
Thanks again
Joe

Hey, don't blow your money away. What will you lose trying to fix it?
The relief valve is only a spring, a ball and a seat.
You went so far to troubleshoot your problem that I believe that you could open your pump and fix it. If the pressure was too low, I would say that some parts are worn and the assembly must be replaced.
You have an excess of pressure meaning that the mechanical parts seems to be OK but you may have a stocked ball (?????)
Don't give up. You can do it!

Well done Joe,
Keep at it and try to fix the pump, if you fail you can replace it which you were thinking of doing anyway.
Regards,
K-BIKE

Try to run it some time revered (change + and -) over a tin with injector or carburator cleaner

What Rene says is a time honoured technique used to try to resuscitate fuel pumps and it is not unusual to see some muck come out when run in reverse and for the pump to run OK afterwards when powered in the correct direction, well worth a try.
Regards,
K-BIKE