Gasoline leaking from air box

[Anonymous]

Hi. On my way through the garage tonight I noticed a couple of drops under my GS850G. Sence I keep on it and am verry pround it dose not leak anything I got right down there and found it to be gas. I traced it to the airbox and dook the chrome cover off to find it pudled up inside. It apears to be coming from the #2 carb. Any ideas? Thanks in advance.

[robben]

I was having a real time dealing with gas in the airbox, and after unsuccessfully rebuilding the carbs, etc ad nauseum... it turned out that one of my rubber tubes between the carb (3&4) and airbox wasn't fitted quite right on the throat of the carb. I traced the problem to the #4 cylinder giving me the flooding trouble. All you need is a pinhole in that tube and it'll flood. I replaced my tubes, since they were hardened over the years, and I couldn't get it to fit right for any length of time, and the flooded airbox was no more.

You can test the tube, by spraying a little ... WD40 (I think) around the tube while the bike's running. If the idle increases, you've got an air leak. This isn't the only reason for the flooding, but it was mine, after exhausting all other avenues of troubleshooting.

Robben

[Anonymous]

Might be a leaky petcock. I have the twin, not the four, so I don't know if no. 2 is the vacuum carb on your bike. If there's a tube going from the carb at the engine up to the petcock, that's it and your problem is a leaky petcock. I'm going through this situation myself.

If the problem is the petcock, whatever you do, DO NOT UNPLUG THE VACUUM HOSE while the bike is hot. I did that the other day, and the bike wouldn't stop spilling gas onto my very hot exhaust pipes. Had to call 911, because it was an extremely dangerous situation and at the time I couldn't think of how to stop it.

Fortunately it never caught fire. Whew. Damn close. And somewhat foolish of me. I sure didn't expect it to leak and leak and leak and leak, though. I just figured it would clear out the line and that would be it. It was a liquid pressure lock situation in the petcock and once the bike cooled down I borrowed the fire truck's pliers to get the tank off, disassemble the petcock and manually close the valve. Had I thought of it, blowing air back up the vacuum hose might have cleared the liquid pressure lock. Might also give you a mouth full of gas, but it's up to you.

But if no. 2 isn't your vacuum petcock source, my entire post is impertinent.

Best of luck.

Michael

[Anonymous]

I believe #2 is the vacume carb

[Anonymous]

If you're sure it's coming from the #2 carb, I would check for a stuck float in that carb. Try tapping it with a screwdriver to see if that frees it up, if not you'll have to pull the float bowl cover.

[Anonymous]

I just checked and the gas is coming from #2 however the #2 is not hooked to the tank. #3 carb is hooked to the tank I am looking at 1-4 while siting on the bike from left to right is that correct?

[Anonymous]

There is only going to be one outlet from the fuel petcock to the carbs and it connects to a feeder line (so to speak) that provides fuel to all four carbs. If it's specifically leaking out of one of the carbs into the airbox, it sure sounds like a stuck float. Did you try tapping on the float bowl of the suspect carb to see if that loosens it up.

[Billy Ricks]

Michael,
If you had fuel coming out of the vacuum side of the petcock then you have a torn diaphram. It's going to leak fuel no matter what you do. Fuel shouldn't get past it to even reach the vacuum side.

[Anonymous]

Quick aside:

Michael,
If you had fuel coming out of the vacuum side of the petcock then you have a torn diaphram. It's going to leak fuel no matter what you do. Fuel shouldn't get past it to even reach the vacuum side.

Yeah, I know. I can't seem to find a replacement petcock I can afford. I think I'll take out the vacuum operated valve and gravity feed to the carbs with a manual emergency valve in the gas line.

Michael

[Anonymous]

I'd be very interested in how you do that! I've thought of it a couple times, but what do you do about the attachment to the tank in the same hole as the petcock?? I'm sure I could jimmy something in there, but I think I'll keep trying to fix the original!! (I'll see tonite if my last mad scientism worked!)

[Billy Ricks]

Someone here converted the stock petcock to a manual one with an off position and no vaccum or diaphram. You might check the Tips section or do a search.

[Anonymous]

I'd be very interested in how you do that! I've thought of it a couple times, but what do you do about the attachment to the tank in the same hole as the petcock?? I'm sure I could jimmy something in there, but I think I'll keep trying to fix the original!! (I'll see tonite if my last mad scientism worked!)

Keep the old petcock in place, just remove the o-ring from the vacuum diaphragm valve and remove the spring that resists the vacuum. That'll let gas always flow. Install an in-line shutoff and replace the vacuum hose with two 3/16 inch vacuum caps from NAPA. I've done the petcock changes, but I don't have my shutoff valve until tomorrow, so let's hope I don't have to remove my tank for anything!

You could also remove the o-ring and spring, and plug the normal opening so that instead of ON and RES you have OFF and RES. Of course, you do have to know when to fill up, and when you switch to OFF (which used to be ON), what gas is in the petcock may still come out.

Now on to fight with my other bike problems.

Michael

P.S. If we want to continue this discussion, maybe we should post a new topic. I'm sure Jasonw24 wants to get his fuel leak diagnosed first.

[Billy Ricks]

I remember now how the guy fixed the stock petcock so it would have an off position. He clipped one of the little tangs off the piece that holds the petcock lever in the petcock so the lever could be turned straight up. In that position the valve is shut off.

[Anonymous]

I had a leaky fourth carb that was going into my air box also, and I read on someone elses post to tap the carb with a rubber mallet and that might free up a stuck float. Well that's what I did and I haven't seen it leak yet, so for all intensive purposes it worked. I had my doubts though!

[robben]

I had a leaky fourth carb that was going into my air box also, and I read on someone elses post to tap the carb with a rubber mallet and that might free up a stuck float. Well that's what I did and I haven't seen it leak yet, so for all intensive purposes it worked. I had my doubts though!

Yep. Same here, only I didn't use a rubber mallet... :twisted: Well, in the beginning I did.. It'd work for awhile, but eventually, leak again. I've been through the entire process of troubleshooting, and of course, the free tips are the best place to start out. Hopefully, you'll nail it before you have to start spending money, like cleaning and lining a rusty tank, another set of carbs, etc... and finally, the new tubes, a few years later. Trust me when I say I spent a long time and many tips to nail that elusive trouble. :?

The good news, I learned a heckuva lot about the bike.

Robben