Fuel filling up my air box!

[cowb0y]

After replacing the R/R, Stator, cdi and generator with Dyna ignition, a repaired fused box and fuel lines (yes, all done tonite), I now have gas filling up my air box when I try to start the bike. I think it is coming out of Carb #2. I have read and reread diagrams of the carbs and vacuum lines. I dont think the lines coming out of the gas tank are mixed up due to their size difference, but I cant think what else would dump gas into the air box. HELP!

[tkent02]

One or more of your float valves are stuck open?

[Clone]

follow the lines, make sure the one coming off the diaphagm goes to the vacuum port on two, and the one coming off the feed, goes to the fuel rail. the other option is to pull both hoses off the petcock, then see if fuel leaks out of both of the ports.

[KnightRider]

A Few Weeks ago I had the same Problem.I went and got carb kits and redid them all.
No Leaking into airbox anymore! YAY.Not The proper way but do them all on the rail so as not to mess up the synce,Then start the screws at about 2/12 to 3 turns to get started, remmember to Use Prime on tank for this. If anyone objects Please fell free to do so =)

[chef1366]

Tap on the bowls and see if you can unstick the stuck float valve. If that's not it it may be bad o-rings on the float seat(s).

[80GS750]

check your petcock.... if its leaking gas it can run into the airbox.....

[doctorgonzo]

FYI, fuel leaking into the airbox CAN catch fire leaving you riding down the road like ghost rider with flames licking up between your knees while it turns your wiring harness in a twisted mess of melted garbage. Ask me how I know... heh,

[cowb0y]

I did install a new petcock recently and now that I think about it, this is the first time that I tried to fire up the bike. How does one test a petcock? It was brand spanking new, when I installed it.

[robertbarr]

Here's a canned response of mine:

Let me point out the obvious: If a carb (or carbs) are overflowing when the bike is not running, you have TWO problems. First, your petcock should prevent ANY flow; second, the needle valve should allow flow only up to a fixed height in the bowl (ie, not overflow). Excess fuel has to make its way past both of these parts.

(A third possibility on old carbs is for fuel to flow past the inlet seat O-ring. [n/a for VM]. That doesn't apply to newly rebuilt carbs, since the owner has just installed brand new. Right??)

I'm not 100% sure why some needle valves leak and others don't, but I'm starting to lean with Keith Kraus' suggestion, which is to use only OEM valves and seats. Simply because it works. The question why is a separate matter. (I have a theory, but no guinea pig to test it on at present).

For the petcock, you'll hear a number of suggestions. I think that the vacuum operated petcock should be kept operational, for a few safety reasons.

Several of the folks here are convinced that petcock rebuild kits are useless, and your only real option is to buy a new OEM petcock.

For now, for people who are 100% sick of carb overflow & the ensuing problems, the consensus then is to go with OEM petcock, seats & needles. it's expensive, but it seems to be the only certain way to correct this BS once and for all.

(I would add: no doubt there are people whose overflow problems began when they installed carb rebuild kit(s). The machining on the parts is often abhorent and inexcusably amateurish, and the f&^%#ing O-rings don't fit correctly. The consensus for a while now has been to buy gaskets IF you need them, valve seats & needles IF you need them, and an O-ring kit.)


The petcock does not, in any way, REGULATE the rate of flow. It should be either on or off. If you have overflow on a running bike, there's a problem with the inlet valve.

Either:

1) the float is no longer buoyant enough or is badly adjusted, or

2)the valve is bad, or is being held open by some foreign matter.

[Narcoleptic_Snowman]

FYI, fuel leaking into the airbox CAN catch fire leaving you riding down the road like ghost rider with flames licking up between your knees while it turns your wiring harness in a twisted mess of melted garbage. Ask me how I know... heh,

Yeah but... I bet it looked really cool... :shock: lol.

[doctorgonzo]

Yeah but... I bet it looked really cool... :shock: lol.

I know. I wish I had pics!

[bwringer]

Here's a canned response of mine:

Let me point out the obvious: If a carb (or carbs) are overflowing when the bike is not running, you have TWO problems. First, your petcock should prevent ANY flow; second, the needle valve should allow flow only up to a fixed height in the bowl (ie, not overflow). Excess fuel has to make its way past both of these parts.

(A third possibility on old carbs is for fuel to flow past the inlet seat O-ring. [n/a for VM]. That doesn't apply to newly rebuilt carbs, since the owner has just installed brand new. Right??)

I'm not 100% sure why some needle valves leak and others don't, but I'm starting to lean with Keith Kraus' suggestion, which is to use only OEM valves and seats. Simply because it works. The question why is a separate matter. (I have a theory, but no guinea pig to test it on at present).

For the petcock, you'll hear a number of suggestions. I think that the vacuum operated petcock should be kept operational, for a few safety reasons.

Several of the folks here are convinced that petcock rebuild kits are useless, and your only real option is to buy a new OEM petcock.

For now, for people who are 100% sick of carb overflow & the ensuing problems, the consensus then is to go with OEM petcock, seats & needles. it's expensive, but it seems to be the only certain way to correct this BS once and for all.

(I would add: no doubt there are people whose overflow problems began when they installed carb rebuild kit(s). The machining on the parts is often abhorent and inexcusably amateurish, and the f&^%#ing O-rings don't fit correctly. The consensus for a while now has been to buy gaskets IF you need them, valve seats & needles IF you need them, and an O-ring kit.)


The petcock does not, in any way, REGULATE the rate of flow. It should be either on or off. If you have overflow on a running bike, there's a problem with the inlet valve.

Either:

1) the float is no longer buoyant enough or is badly adjusted, or

2)the valve is bad, or is being held open by some foreign matter.

Can we send out someone to shout this through a bullhorn at new members of the site? No?

Engraved on a nice plaque somewhere?

Maybe at least added to Basscliff's Hall Of GS Wisdom?



I would add that a common source for the gunk propping open float valves is mung from an ancient, internally corroded or decaying petcock. The petcock has (or should have, unless someone already messed with it) a very efficient mesh fuel filter built in. So basically, anything that ends up getting past that filter came from the petcock itself.

If your tank is rusty inside, it is possible for extremely fine particles (finer than talcum powder) of rust to get through and accumulate in the float bowls over time. However, these generally won't cause immediate problems (although they can build up and clog various passages after a while) and won't prop open the float needles.

Let's just say that opinions vary widely on inline fuel filters, and I don't use them on my bikes.

[doctorgonzo]

Preface with I know I should change this at some point...

I ordered a petcock from Z1 and the bolt spacing was correct, but the filter wouldn't fit through the opening into the tank. I didn't want to wait for the return, etc... so I just pulled the filter off and bolted it on. This also means I have no reserve tank. There is one opening, at the bottom straight into the petcock. I run one of the clear plastic high flow fuel filters from Z1 just the other side of the petcock in the fuel line. I guess the danger is gumming up the petcock with stuff not getting caught by the filter.

[cowb0y]

Thank you gentlemen for all your aid, now and in the past. Today, my bike ran beautifully for the first time in three months!! \\/
I have sought the wisdom and guidance of many of you here at the GS Forums and am very happy with the responces I have received. Thank you all as I am now back on the road. :-D
This is a great resource and I am super stoked it functions as it does. Thank you all again!