Fuel leaking from carb hose on 85 FJ1100

[Gearbox Paul]

I went by my new to me bike this morning and there was puddle of gas under the bike.  Fuel is coming out of a hose attached to the right side carb (right side carb is #4 I assume).  I think this hose is a bowl vent hose. I don't know too much about these Mikuni carbs.  Assuming that it is a vent hose, the other three carbs don't have this hose.  Does that mean the right side carb vents all 4 bowls???

I assume incorrect float height or failed o-ring or debris or something is causing one of the bowls to overflow.   

It also means that I have fuel flowing through the petcock, which isn't right.  It looks like an OEM petcock, as far as I can tell, with a lever to switch from ON to PRI (prime???).  I pulled the tank off and fuel flows from petcock regardless of which position lever is in.  I assume I need replace/rebuild the petcock as well. 

Appreciate your thoughts and guidance.   

[Pat Conlon]

Let me guess....Store your bike with E10 fuel?

That hose is a choke vent hose and you should have 3 more, one on each carb....in addition you should have 2 larger fuel bowl vent hoses, one between carbs #1 and 2 and the 2nd between carbs #3 and 4  (6 hoses total)

Your float level is fine, you have gunk holding the float needle off the needle seat.

Yes, that petcock should shut off the fuel (ON position) when there is no engine vacuum. Time for a rebuilding kit from RPM: http://www.rpmracingca.com/proddetail.asp?prod=M%2FC%3AVacuumPetcockRebuildKit

Before you do the petcock work... try running a tank of fuel with Seafoam thru your bike....see if that cleans things out.

Don't leave E10 fuel in your bike.
Check your gas tank for rust and sediment.
Don't be tempted to install a fuel filter. Our gravity flow FJ's don't like the restriction in flow.
Clean and seal your tank...if needed.

Cheers

Pat

[86FJNJ]

Not sure who but another user in the group removed the mesh screen on his side panels and installed a manual fuel valve right on the inside of the panel so he can sneak his fingers in to manually turn fuel on/off, might be worth considering...leaking fuel in your home/garage is scary stuff especially if you just pulled in from a ride and bike is hot. Probably one of the more economical options.

[Pat Conlon]

.....leaking fuel in your home/garage is scary stuff especially if you just pulled in from a ride and bike is hot.....

Absolutely true ^^^ especially if you have a water heater in your garage. When those gasoline vapors reach the level of the pilot light.... things will get real interesting.

The beauty of the 84/85 petcocks is the Prime (P) setting, where gas flows all the time. The later 86/87 petcocks don't have this P setting.

With the petcock set on Prime you can install a normally closed 12v fuel solenoid. The solenoid will open when the key is turned on and closed when the key is off....

I would rather have a fuel pump and a real honest to God fuel filter. My carbs will be happier.
Our tanks aren't getting any younger.

[FJ1200W]

Also never, ever (over)fill the tank after a long ride and park it.

[Gearbox Paul]

Let me guess....Store your bike with E10 fuel?

That hose is a choke vent hose and you should have 3 more, one on each carb....in addition you should have 2 larger fuel bowl vent hoses, one between carbs #1 and 2 and the 2nd between carbs #3 and 4  (6 hoses total)

Your float level is fine, you have gunk holding the float needle off the needle seat.

Yes, that petcock should shut off the fuel (ON position) when there is no engine vacuum. Time for a rebuilding kit from RPM: http://www.rpmracingca.com/proddetail.asp?prod=M%2FC%3AVacuumPetcockRebuildKit

Before you do the petcock work... try running a tank of fuel with Seafoam thru your bike....see if that cleans things out.

Don't leave E10 fuel in your bike.
Check your gas tank for rust and sediment.
Don't be tempted to install a fuel filter. Our gravity flow FJ's don't like the restriction in flow.
Clean and seal your tank...if needed.

Cheers

Pat

Thanks Pat.  I just pick up this bike a week ago or so.  It's quite possible that the previous owner left old E10 fuel in the tank.  I removed the tanka and drained the fuel.  I'll rebuild the petcock so that I can stop the free flow of fuel that is leaking everywhere, that's my first priority.  After that, I can try sea foam or break into the carbs to clean them out.  Yes one of previous owners installed a fuel filter between the tank and the carbs.  Because of that bulky fuel filter, I can't route the fuel line from the tank to the carbs as per the drawing on the air cleaner assembly.  And one of the fuel hoses is kinked.  Should I just rempve the kicked hose and replace it without the fuel filter? 

Regarding the carb vent hoses, the choke vent hose is missing on carbs 1, 2, and 3 and the fuel bowl vent hoses are also missing.  How much of an issue are these missing vent hoses?

[Pat Conlon]

Paul, you need the carb hoses.
Think of it this way.... When the bike is running, the engine vacuum opens the petcock and the carbs are full of fuel, now if one of those other 3 carbs starts free flowing fuel, or you have a stuck float, do you want that fuel dropping down on the top of your hot engine....or would you rather have the fuel run through a hose and exit at the bottom of the bike?
Tip: I put number tags on the ends of small choke vent hoses corresponding to the carb# and L and R on the larger vent hoses. That way,  if I see gas dribbling I know what carb is misbehaving.

Good on draining the tank, now wash it out (see any rust?) and clean the petcock inlet screen.

Remove the fuel filter. Follow the factory route for the fuel line, it's counterintuitive until you visualize how low the petcock outlet is positioned.
If you don't, as your engine heats up the fuel line softens and a pinch will occur.
Ask me how I know this...

So, 1) put all the carb hoses on, 2) remove the aftermarket fuel filter, 3) follow proper fuel line route 4) clean out tank 5) rebuild petcock, 6) run a tank or two of Seafoam.
If after a tank or two of Seafoam, if you still get gas dribbling out (onto the ground and not the top of your engine and now because your petcock is fixed, it only dribbles out while the bike is running) it will then be time to take your carbs off for cleaning and fresh o rings on the float needle seats.
Report back at that time....

Cheers

Pat

[giantkiller]

Not sure who but another user in the group removed the mesh screen on his side panels and installed a manual fuel valve right on the inside of the panel so he can sneak his fingers in to manually turn fuel on/off, might be worth considering...leaking fuel in your home/garage is scary stuff especially if you just pulled in from a ride and bike is hot. Probably one of the more economical options.

Yeah I did that. If you fold the wire mesh down on the top slot on the left side panel. You only notice if I tell you it's missing. And you can fold it back if you change out your petcock. I had RPM install their pingel petcock when I was out there for the Cali rally. Going to install one on my 92. Just cuz the stock one is so hard to turn off n on when removing the tank.

[Motofun]

The first trick to try with a suspected stuck float is with the bike on the center stand use the handle of a large screw driver and give the offending carb a few good whacks....It's saved me once or twice from chasing my tail. 

[Gearbox Paul]

Yup, did that already, but didn't work for me.

[Pat Conlon]

I forgot to mention...check your crankcase oil level, do a sniff test, to be sure fuel didn't get past your piston rings and corrupt your oil.

[Gearbox Paul]

Paul, you need the carb hoses.
Think of it this way.... When the bike is running, the engine vacuum opens the petcock and the carbs are full of fuel, now if one of those other 3 carbs starts free flowing fuel, or you have a stuck float, do you want that fuel dropping down on the top of your hot engine....or would you rather have the fuel run through a hose and exit at the bottom of the bike?
Tip: I put number tags on the ends of small choke vent hoses corresponding to the carb# and L and R on the larger vent hoses. That way,  if I see gas dribbling I know what carb is misbehaving.

Good on draining the tank, now wash it out (see any rust?) and clean the petcock inlet screen.

Remove the fuel filter. Follow the factory route for the fuel line, it's counterintuitive until you visualize how low the petcock outlet is positioned.
If you don't, as your engine heats up the fuel line softens and a pinch will occur.
Ask me how I know this...

So, 1) put all the carb hoses on, 2) remove the aftermarket fuel filter, 3) follow proper fuel line route 4) clean out tank 5) rebuild petcock, 6) run a tank or two of Seafoam.
If after a tank or two of Seafoam, if you still get gas dribbling out (onto the ground and not the top of your engine and now because your petcock is fixed, it only dribbles out while the bike is running) it will then be time to take your carbs off for cleaning and fresh o rings on the float needle seats.
Report back at that time....

Cheers

Pat

Thanks again Pat.  That's sounds like a good plan.  And I'll install the missing hoses on the carbs - that makes sense.  Do you know the size of the two larger float bowl vent hoses? 

And I'll check the oil level and smell.  Only thing I'm struggling with right now is finding a petcock rebuild kit.  RPM is out of stock and I need it shipped to Canada. 

[RPM - Robert]

We ship to Canada and we got 5 kits in this morning.

[Pat Conlon]

.......and Robert for the score! 

I think I used 5/16 for the 2 float bowl vents.  Run them along with your choke vents down the back side of your engine, not too long mind you....  just long enough to get the fuel off the engine.

One time in band camp, I ran my hoses too long and the end of one of my float vent hoses melted shut from the tip touching the exhaust collector...... I had a hard time figuring out why all of a sudden my bike was surging at freeway speeds.  Those float bowls gotta breathe, they get cranky when they can't....

[giantkiller]

Yep I had to drain my oil in the parking lot of a hotel. On a ride around the lakes up through the U.P. and skip breakfast. And catch up to the group. Easy enough all Harleys. Luckily the grounds guy for the hotel was was there to take the oil and new drain pan. The rapping on the float bowls worked that time. But the crankcase was already full.