Diagnostic assist please!

[moovyz]

My '89 FJ1200 with 28k (I've owned for the 8k end) has been running very good for the past 2 years. I keep it well maintained and am particular about and good at syncing the carbs.

About a month ago I was on a 30 minute easy ride on the back roads and it developed a miss mostly noticeable under accel. It's a single cyl miss. I nursed it the last mile home and intended to get into it in a few days.
When I parked it I noticed a small amount of gas dripping down from an overflow hose behind the center stand. I shut it off and it stopped but when I turned key on (without firing) it still dripped fuel.

So I'm pretty convinced it's a float needle not seating and fuel is not shutting off to that carb, yes?

Here's the part where I need help...

I waited a week and started it and it did the same thing for about 20 seconds then started running fine again. I rode it a couple short rides over the next few weeks and no return of issue.

Today I got on it and it started doing it... off and on for the next 5 miles while I returned home. Seems like I can get it to stop doing it when I'm pushing it hard but when I ride at a set speed for a bit it starts doing it when I begin accelerating. So again I think it's a float issue.

I'd like to know if anyone has ever had an issue like this. Best guesses... float needle rubber not seating always? Or maybe a small hole in the float so it's not rising all the way? Or could it be dirt? (I kinda rule this out because it's intermittent. Should have blown clear by now. And lastly, could it simply be a float not set at the right height? Again, that doesn't seem right because it's been fine for a long time. The only time I've had issues with diff float heights is after a rebuild or teardown.

My problem is I have a bad back and have a really hard time working on the bike for long periods, especially when bending forward. And I've never been good at getting float heights set right.

Opinions of any kind are cheerfully appreciated. And does anyone have a trick to bench test the float workings ?

all responses are welcome. Glen Carlisle, PA

[Alte Fahrt]

I had a similar problem on my 88. Just a little gas coming out the overflow once in a while. This led me to believe that I also had a float or needle valve sticking. I discussed this with a friend who is a long time rider  and part time mechanic. He told me that this is a fairly common problem, especially after sitting a while. He advised me to take it out on a long run over not so smooth roads. I did and it stopped. I guess it just needed to be shook up a bit. Hope this helps.

[a.graham52]

No need to give you any advice. Sounds like you know all the possibilities. You could try hitting the float bowls wit a small hammer or pipe to see if it will dislodge a stuck float  . But it sounds like it should come apart and have a look.

Harbor freight sells a motorcycle table lift for about 400. It "should" lift the fj and the worse complaint iv herd about them is the hydrolic jack failing. But it's easy enough to replace with a better unit.

[FJmonkey]

You can check your fuel levels by using a small clear hose that fits the drain port on the bottom of the carb bowl. Withe the other end raised above the fuel level of the carb, open the drain and you will see the fuel level. Do this for each carb and see if one or more is off from the others. You can also identify which drain hose is leaking fuel to narrow down what carb or carbs need attention.

[fj1289]

May be a little crud in the floatbowl

[red]

Seafoam.  Try less than half a can of that magic stuff in a near-empty gas tank, then fill the tank.  Run it, give it a few days, and see if the problem persists.  I'd need to see that stuff fail to fix your problem, before I picked up any tools.  I've seen it work too many times.  Only then, if the Seafoam does not work, it's time for tools.

As a side note, your fuel petcock or fuel pump should be shutting down the fuel flow when the engine is OFF.  (Seafoam may fix that problem, also.)  If fuel keeps dripping when the engine is off, you can get fuel into the crankcase, ruin the oil, and ruin the engine (big time!).  Check your oil level sight window, each day before you start the engine.  If the oil level goes UP due to leaking fuel, you need to change the oil before you start the engine.  During the repair job, you can disconnect the fuel line, open the gas cap, turn on the key, and let the fuel pump run a gallon of fuel into a gallon gas can, to clear any crud that was in the pump.  When you turn off the fuel pump, the gas flow should stop, not keep dripping forever.  RPM has new fuel pumps for less than the OEM pumps, if yours does not stop the fuel flow.

Because of ethanol, gas tanks can get rusty fast, these days.  Tape a strong (neodymium) magnet onto the lowest part of the fuel filter, and never take it off before you remove the fuel filter from the bike.  The magnet will catch and hold even microscopic rust, before it can get you into trouble.  Put the same magnet on the next new fuel filter, certainly.  My $0.02 worth.

Cheers,
Red

[simi_ed]

O-rings at the needle seats!  Get the screw/o-ring kit that Randy sells. It means you'll need to R&R the carbs, but you'll fix the issue.  If they've never been changed those o-rings are ~28 years old!
My 2¢.

[moovyz]

First, allow me to thank all those "helpers" who replied. It's nice to have a think tank available.

To "Red", I get no fuel leaking with the engine not running, key off. And I only got fuel coming out once when I first noticed the missing and pulled over and hit the kill switch. The key was still on, therefore the fuel pump was still running and then I saw some fuel still coming out the overflow until I turned the key off. That's what has me thinking it has to be a float needle not sealing off.

I had this issue once on an old Yamaha but it was because a float got a hole in it and filled with gas so it never shut itself off. But that was a constant issue. This comes and goes so I know the float must be "floating".

I guess I'll try the Seafoam first and take it on a 30 mile highway run and see if it stops. I'll keep you informed.

[wirehairs]

Like Simi said, my money is on o-rings.  I base this on the time I had fuel leaking, and it was one of the o-rings in my fuel rail (the connector between the individual carbs).  They would dry out when the bike was not run for a while, and then once exposed to fuel, would swell up and the fuel leak would stop.  So that's what caused it to come and go.

I think the result is still the same: you still need to pull the carbs, break the rack, and inspect all your o-rings (and look for deposits/sludge) while you are in there.

[Mark Olson]

You can ride it off a couple of curbs to shock the floats along with the seafoam treatment . If the problem comes back , you gotta pull the carbs and clean them . sometimes gunk buildup on the float pin causes them to stick and not seat.