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91 only runs on 1 and 4 cylinders

Started by jono, July 28, 2020, 05:05:24 AM

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Pat Conlon

Quote from: ribbert on August 30, 2020, 08:54:58 AM

Pat, while we're on the subject, to clarify a safety concern you had earlier (below)...

"With the vacuum petcock the fuel flow stops when the engine stops.
With the electric solenoid the fuel flow stops when you turn your key off.
In an accident with the engine stalled, you may not be able to get to the key to turn it off.

The solenoid is "in-line" it doesn't override any of the original plumbing, it is additional to the standard set up. For all intents and purposes, it has no more control over the fuel flow when it's open than the 2" piece of hose it replaced.
It does not present any sort of risk because you can't turn the ignition off.

Hi Noel, my above comment pertained to the idea that you could *replace the FJ vacuum petcock* with your electric solenoid (correctly sized, not the 1/4" solenoid you show)
Assuming that the solenoid is wired to the ignition key, the fuel flow will not shut off unless the key is off. Again, we were talking about gravity flow fuel systems and vacuum petcocks, not the fuel pump system.

If your fuel pump dribbles gas when shut off....that is an abnormal condition. Period.
It indicates to me that the diaphragm or seal is leaking in the fuel pump, which indicates to me that the condition will get worse, not better. Oh, you may hope it gets better, but it really won't....

So.....when you find yourself by the side of the road with a stalled FJ from fuel starvation due to a knackered fuel pump, you can say to yourself, "Well, that fuel pump did try and warn me".

That's when you use this:

Every fuel pump FJ should have this ^^ in their tool kit. It will get you home.
1) Free Owners Manual download:
2) Don't store your FJ with E10 fuel
3) Replace your old stock rubber brake lines.
4) Important items for the '84-87 FJ's:
Safety wire:
Fuel line:


well I got the back brake kind of working on Sunday and took it for a short ride around a private road close to were I live. When I started the motor after about 30 seconds it started dumping fuel out 1 or 2 of the 4 overflow pipes on the carbs so took the tank off and started it again with the tank next to the bike and it kept leaking so I kept tapping the carb bowls and revved the motor for a couple of minutes and it stopped finally, then  I took it for short ride and it didn't leak again at idle, and Ive just checked it in the shed and it hasn't leaked again so I'm pretty sure I must have stirred up some crap in the bowls when I removed them to fit new o rings and seal them to the manifolds, so it looks like its problem solved. This weekend i'll fit my refurbished brakes take it for  one last ride then strip it to the motor in the frame  and paint the motor and bring the frame back to original silver then Ive only got to fix all my body work ,I didn't really get above 4 or 5 thousand rpm but it feels pretty grunty  and very smooth and responsive Im looking forward to riding it properly .the manifold rubbers look a bit dodgy as well there defiantly not leaking  but I'm going to get some new ones at some stage and when I do I'll get a bowl gasket set from RPM as well and clean the bowls out properly

here it is back from it's first ride since I stripped it

thank you  all for your good advice

1991 fj1200


Mine leaked a few times, I cured it by blowing into the carb overflow pipes. I must have cleared something that was holding the float needle valve.

Did this with the engine running, think I can remember the noise that the float made, maybe it was bouncing up and down!
BMW 1150GS
Moto Guzzi California 3


good idea if it happens again ill try that. Ive really got to take the bowls off and clean them but its a big job .
I can get aftermarket float valves and seats and new gaskets from a bike shop here in NZ but I'm weary of
opening the carbs ,it runs and idles really well at the moment

1991 fj1200


I didn't want to open them up either.

One time I I removed the fuel pipe and sprayed carb cleaner into the pipe. Still leaked.

Love my guzzi,  undo one bolt, access the float bowl.

Loved my BMW RT100 as all I had to do to access the float chamber was pull the sprung loaded clip...... Modern bikes! LOL
BMW 1150GS
Moto Guzzi California 3