I have a problem that I need help with (beware, it's a long one!).

Out on a run, everything going lovely when the engine starts breathing heavily and proceeds to stall and refuses to stay running without quite a lot of revs. Pull into a side road and get out for a think and a poke about. The engine refuses to stay alive with anything less than a few thou revs. So, I leave it for a little while and have a ciggy.
After a few minutes, the engine starts and idles (poorly) so I decide the best thing to do is get it home.
The half mile home was pretty painful as I had no power at all and the engine was still sounding pretty rough.
Once I arrived home, I shut off the engine but left the ignition on. The fuel pump continued to run....
Now, when I turn on the ignition, instead of running until the lines are full and pressure is built up, it continues to run indefinately and the engine will idle (sounding rough) but any attempts to pull off are met with a lack of power and almost instant stalling.

In my efforts to diagnose, I have:
1) Checked all fuel lines are clear (with a fairly high powered air compressor)
2) Detached fuel pipe at Carbs to check that the pump is working - good steady flow of fuel and stops when pipe is blocked up with finger (to simulate pressure of full fuel lines).
3) Had all the carb covers off - diaphrams and needles look OK and everything is clean.
4) All points checked (sounds like it is still running all 4 cylinders anyway but worth checking).
5) New fuel pump - same continuous running as the original pump.

It seems to be displaying the characteristics of fuel starvation but I am sure that, up to the carbs, the fuel is pumping OK and the fact that the pump operates continually would suggest that there should be no problem with fuel reaching them.

The only thing I haven't checked (as I am not sure where you would start) is the distributors themselves.

Any suggestions gratefully received.

cheers
tom

It sounds like you may have blocked jets in the carbs, or possibly water in the petrol, try taking off the float bowls and see if there is any debris in them, if there is,you will have to strip the carbs and blow out all the jets with compressed air.
Had you filled the tank prior to this happening? and do you have an inline fuel filter?

Al.

i]Originally posted by uberf1end
I have a problem that I need help with (beware, it's a long one!).

Out on a run, everything going lovely when the engine starts breathing heavily and proceeds to stall and refuses to stay running without quite a lot of revs. Pull into a side road and get out for a think and a poke about. The engine refuses to stay alive with anything less than a few thou revs. So, I leave it for a little while and have a ciggy.
After a few minutes, the engine starts and idles (poorly) so I decide the best thing to do is get it home.
The half mile home was pretty painful as I had no power at all and the engine was still sounding pretty rough.
Once I arrived home, I shut off the engine but left the ignition on. The fuel pump continued to run....
Now, when I turn on the ignition, instead of running until the lines are full and pressure is built up, it continues to run indefinately and the engine will idle (sounding rough) but any attempts to pull off are met with a lack of power and almost instant stalling.

In my efforts to diagnose, I have:
1) Checked all fuel lines are clear (with a fairly high powered air compressor)
2) Detached fuel pipe at Carbs to check that the pump is working - good steady flow of fuel and stops when pipe is blocked up with finger (to simulate pressure of full fuel lines).
3) Had all the carb covers off - diaphrams and needles look OK and everything is clean.
4) All points checked (sounds like it is still running all 4 cylinders anyway but worth checking).
5) New fuel pump - same continuous running as the original pump.

It seems to be displaying the characteristics of fuel starvation but I am sure that, up to the carbs, the fuel is pumping OK and the fact that the pump operates continually would suggest that there should be no problem with fuel reaching them.

The only thing I haven't checked (as I am not sure where you would start) is the distributors themselves.

Any suggestions gratefully received.

cheers
tom

check the pilot jets aren't blocked. Maybe the valves in the float chamber/s aren't closing properly and you are flooding 1 or more of the cylinders???

It does sound suspiciously like dirt in the system, so I can't add more to what has already been said about that.
However, it may also be a problem of too much fuel. What pump are you using? If it's not a compliant bike pump, but one from a car, you would be pumping at too high a pressure. The result of that is the needle valve seats will give in, which can result in the engine being flooded.

Thanks guys. I had previously fillled the tank but I had to syphon off the fuel to check the lines at which point, I ensured that the tank was clean. I do have an inline fuel filter which looked fine.
The pump was from a blade, but I have replaced that with a Ninja one and still the same problem.

I'll have the float bowls off today and clean up the jets, see if that makes a difference.

Are you filling up with a jerry can? I heard that fuel can gum up when left to sit in a jerry can for too long and cause problems.

Ian

Is your tank properly vented?

Reason I say this is that I used to have a m/bike which suffered from a blocked-up vent hole.
Ran nicely for a while, then went rough, then stopped. After a while the engine could be started again, then the problem happened again a few miles later.
Sounds familiar?

Of course, you may have already checked this...

cheers,

David

Fuel was fresh from the pump and was syphoned to a brand new jerry can, then back again. Tank venting OK.

Still following the float bowl/jet route but having some difficulty with seized screws at the moment.....there's always one or two (or 12!!) that refuse to budge....I reckon Copper-slip should be much more widely used....Still, I'll wait to see if the WD40 can work some magic before I reach for the drill.

Give them a swift tap directly on the screw head with a light hammer (and drift if necessary) this will usually break their grip.

HTH Stu.

Have you got a pressure regulator in the fuel pipe. We did not and the fuel would over power the floats and flood the engine.

Have you checked the eletrics because we had a problem that was kinda similar and it turned out to be the coils

Cheers

Jim

[Edited on 13/8/03 by Jim]

Jim:

quote:

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Have you got a pressure regulator in the fuel pipe. We did not and the fuel would over power the floats and flood the engine.

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