leaking fuel *help*

[bonanzadave]

Started the bike this morning to find significant fuel dripping from the bowl drain screws on each carb. Too much to even ride it. The Bike has about 50 miles on it this season and has been sitting unstarted for about a month. Drips stop as soon as the engine is turned off. ????? Gotta go to work so thats all I can tell you for now. Any "check this first" advice ? Thx.

 

[Nessism]

Hum, since the fuel dripping stops when turning off the engine that suggests your petcock is working properly.

What about a fuel tee leak, where the fuel is dripping down the side of the carbs and finally off the lowest point, the drain screw? If this is happening I suspect there would be more fuel off the center carbs though.

 

[LAB3]

Fuel tee (and where the supply like meets it) leak is a good starting point, if it isn't there my next bet would be a floats sticking. That's often confirmed by tapping on the float bowls to free up the needle, if that's the case my next move would be to drop the bowls and see if there's any crud in there.

 

[rphillips]

My CB1100F has done this the past few yrs., at the first start up after its winter sleep. It will leak very fast drips for first, maybe 10 to 15 min., then quit completely. 50 mi. would be way more than it takes to stop. Thinking an "O" ring where carbs are connected, slightly shrink when gets dry, then swells enough to seal after get wet with fuel again. Wouldn't think this of a carb "O" ring, but what else???

 

[Nessism]

Rubber, whether an O-ring or a rubber coated fuel Tee, will shrink and dry up with age. Soaking in fuel will cause the rubber to swell up. I think that's part of the scheme with the design, and a reason nitrile is used so often for fuel system O-rings and such.

 

[bonanzadave]

What about a fuel tee leak, where the fuel is dripping down the side of the carbs and finally off the lowest point, the drain screw? If this is happening I suspect there would be more fuel off the center carbs though.

Thx guys

Ed, yes. Its on the side stand so more fuel on the down hill side. Where is this Tee ?

 

[Nessism]

Middle of the carbs attached to the fuel feed hose.

 

[bonanzadave]

Fuel line is dry and stiff as a brick. What size is that ? Got an O'Reilly right around the corner. Vac hose size too if you got it.......

 

[Nessism]

Fuel line is 7mm. Auto part store fuel line sucks compared to the real deal Suzuki stuff.

 

[bonanzadave]

Probably what I had on there. If I said its 10 yrs old its more like 20 ! Auto has got to be better than what I got.......

Denis Kirk is next day for me

 

[bonanzadave]

Nope. That was not it.

Finding that 7mm hose is a real worm hole. I went to 3 MC parts and one auto parts. None. I put a new 5/16 on. What a PITA getting it on the T. Still drips.

On the side stand both the middle carbs have drips and the left (down stream) carb as well. Not so much the right (up stream) carb.

Sooooo.... can I get the bowl screws out with a angle philips ? Should I have some bowl gaskets before I dig in ?

Edit: Got the two left side bowls off. Both floats free with very little sediment. I need a 1/4" gear wrench.

 

[bonanzadave]

All the bowls are off. Very little sediment and all floats and needles are free. Now that I think about this wouldn't a stuck float or needle just fill up the crankcase with gas ? Even with all the floats and needles stuck there wouldn't be that much gas leaking outside the carbs.

Ill fight the bowls back on and re-focus on the T. Sux that you can hardly even see the T and that's with the tank off.....

Starting to wonder if I should just yank the whole rack......

 

[Nessism]

Yes, yank the rack. That's what I'd do anyway. Set them up on your workbench with a remote fuel feed and see where the leak is coming from. As mentioned earlier, I was wondering about the fuel Tee proper, not from the feed hose. Anyway, that's just speculation, with the carbs on your bench you can see for sure.

 

[tatu]

This happens a lot with my bikes because they have long unused periods, It is always the tee piece and the straight joiner between 1 & 2, 3 & 4 they drip for a few minutes then seal up. I put a rag under the carbs till it stops... I saw some nice turned ones on ebay, I think when the time comes I will use those and viton seals.

 

[Nessism]

Nitrile rubber is good for fuel system parts because they swell slightly and afford a nice tight seal. Viton is for heat.

 

[bonanzadave]

Yes, yank the rack.

Thxs again Ed, but you have to be more insistent with hard heads like me ! Remember, this was dripping a lot of gas. At least an oz a minute...or more.

Tank is off. I put the bowls back on. Used a blow gun to get every thing dry. Put a funnel on the new fuel supply hose and dumped in a beer can full of gas. It almost took the whole can (12oz) and now after an hour the funnel is empty. No drips.........I got a bright LED light on the T and its dry as a bone.

Its on the ctr stand and the oil level has not moved so I don't believe gas is leaking into the crankcase.

Any guesses on whats gonna happen when I put the tank back on ???? There is 3-4 gals in it and Im wondering if that head pressure will cause it to leak again.......

 

[Grimly]

If the tiny extra head pressure of the tank causes the fuel valves to leak, they need attention.

 

[Nessism]

If the tiny extra head pressure of the tank causes the fuel valves to leak, they need attention.

Agree. Real deal Mikuni brand float valves can be had from Dennis Kirk for about $15 each if it comes to that. Money well spent if the fuel level is too high and can't be lowered through conventional means like adjusting float height.

 

[bonanzadave]

Got company over and I gotta burn some burgers and drink some beers. Stay tuned......

 

[tatu]

Nitrile rubber is good for fuel system parts because they swell slightly and afford a nice tight seal. Viton is for heat.

Got it, thanks