Fuel Leak when sitting overnight

Well I'm back again about my nephew's FJ600

We just got the carbs cleaned and rebuilt with new seals etc.

It was running beautifully, so much so it we finally got it new tires and got it inspected.

Next thing you know we find a puddle of fuel under it one morning.

Looks like it's coming out the overflow tubes.

Should we be looking at the floats again? or could this be a problem with the Petcock?

Thanks for your continued help

M

 

It's a FLOAT issue, or at least a float valve not shutting off issue.

A petcock problem will only "enable" it; the root cause is a float not shutting off.

 

If you had the petcock in the ON or RES position when it leaked, then there is also a petcock problem. The petcock should only flow gas in the ON or RES position when the engine is running and providing vacuum to the petcock.

 

OK, so what you are both saying is that it is BOTH the petcock and the floats.

Because if I understand this correctly, even if the floats are not closing the valves correctly, the petcock shouldn't be allowing fuel in when it's just sitting. (not running)

I am getting that right?

M

 

I also just remembered that this bike has a PRIME position on the petcock.

However, it was set to the ON position when it leaked.

M

 

yep, then its a petc0ck issue as well.

the reason its actually leaking is the floats, but the petcock failing is enabling that to happen. if the petcock was working properly then it wouldn't allow the carbs to flood.

good luck!

 

Correct. The petcock is vacuum operated, and should only allow fuel flow when the motor is running, if it's in ON or RES.

PRI bypasses the vacuum shutoff and allows fuel to flow, all the time.

The float valves are supposed to shut off fuel flow once the float rises to the correct level.

If the whole system is working correctly you could leave it on PRI and nothing bad would happen (even for a week, but don't. And don't ask.)

If it's peeing gas, then it has a stuck or mis-adjusted float; PLUS an unending supply of gas to pee with, indicating a failing petcock.

 

Thanks Everyone

Looks like that'll be a season-ender for us.

I just don't think there will be enough riding time until we get it fixed

So we'll have to make it one of the many winter projects



Thanks again

M

 

Just be sure the motor isn't perpetually filling your crankcase with gasoline. If that's happening it could cause serious damage before you "fix" it.

 

Disconnect the Gas Tank? drain the bowls?

 

Disconnect the feed line; the bowls can't overflow unless they have a fuel supply.

HOWEVER: Depending on how bad the issue is, it could be dumping enough fuel when it's RUNNING to pollute the oil.

If you're going to put off fixing it, closely monitor the oil for a strong smell of gas. If/when that happens, you'll need to do another oil change.

 

Thanks Fitz!