fuel coming out of air vent under fuel door


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hotwire
Posts: 48
Joined: Mon Sep 05, 2011 8:57 pm
Location: mosheim,tn
Motorcycle: 1985 gl1200 aspencade, sold
1988 gl 1500
2006 1300 VTX

fuel coming out of air vent under fuel door

Post by hotwire » Thu Aug 03, 2017 9:37 pm



Hi, guys. I was riding today, on a pretty hot day with my 88 1500. I had noticed on occasion (especially on hot days) after bike sets, say at the store for about twenty minutes, it would be hard to start. Crank over good, but wouldn't fire until I crank open the throttle, and I could smell raw gas, as if it is flooding. So I ordered a repair kit for my auto shut -off valve and rebuilt it. Have rode since, on cooler days, and bike would start at the touch over the starter button. But it started hard again today, and after riding on the return trip home, (about five miles from the store, I could still smell gas strong, and looked down. Drops of fuel were blowing out from under the fuel door. I stopped beside the road, shut off the bike, opened the door, thinking I may have a hose working loose from the shut off valve after I had worked on it. But Gas was coming, ever so slightly, from the air vent pipe which comes up from the carbs, ( I assume this is the vent for the float bowls? ). I started the bike back, it stopped, and I rode on home, (about ten miles or so ), with the fuel door open, (Afraid of a fire, of course ), and kept one eye on it. Noticed just a very small drip into the overflow tray occasionally. Got her in the garage,took off the top cover, tried to start and watch,engine did not want to hit and run, and gas was coming out of that vent tube quite a bit. Anybody have any idea what may be causing this ( I guess flooding? ) to happen. Bike runs fine, no other apparent carb issues. Have to usually choke engine when cold, but warms up quick. First time for this, though. Is it possible the vent pipe hoses are kinked or plugged, does anyone know if this would cause this condition, perhaps? Thanks ahead of time for all tips, greatly appreciate the help.



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Bluewaterhooker0
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Location: Tampa, Fl
Motorcycle: 1997 Goldwing GL 1500 SE

Re: fuel coming out of air vent under fuel door

Post by Bluewaterhooker0 » Thu Aug 03, 2017 10:49 pm

I haven't had any issues with mine, and therefore haven't worked on it, but as far as I know there are only 3 hoses in that area. The fuel into the petcock from the tank and pump, the fuel out of the petcock to the carbs, and the vacuum hose that opens the valve to make it work. If it's either of the hoses going to the carbs, it sounds like a fuel leak from the carb supply hose, or the vacuum hose that should have no gasoline in it at all. You may not have gotten your petcock rebuild done quite right, and its sucking fuel into the vacuum hose, or you may just have a leak in the carb supply hose. That's my best guess.

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Erdeniz Umman
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Location: Ankara Turkey
Motorcycle: 2000 GL1500SE

Re: fuel coming out of air vent under fuel door

Post by Erdeniz Umman » Fri Aug 04, 2017 3:04 am

There is a service bulletin (GL1500 #1) for 88 models, I recommend you read it before insisting on starting the bike with this failure.

Here is the link.
http://www.gwfyn.dk/gwdata/service1500/sb01-gl1500.pdf

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ct1500
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Re: fuel coming out of air vent under fuel door

Post by ct1500 » Fri Aug 04, 2017 6:17 am

One or both of your carburetors are flooding due to improper float level, defective float valve or the float itself. Remove top shelter then remove rubber vent hoses which come from each carb to the metal vent pipe. Start up engine then observe from which carburetor the gas is coming from.
This at least gives you a heads up as to where the problem lies left or right side.
This is what I do
Local and need repair help with your 1500, Valkyrie or ST please PM

hotwire
Posts: 48
Joined: Mon Sep 05, 2011 8:57 pm
Location: mosheim,tn
Motorcycle: 1985 gl1200 aspencade, sold
1988 gl 1500
2006 1300 VTX

Re: fuel coming out of air vent under fuel door

Post by hotwire » Fri Aug 04, 2017 10:56 am

Thanks for the replies, guys. I failed to mention that when I remove the gas cap, there seems to be a lot of pressure building up in the fuel tank, so I guess my next question is: Is it possible along with a kinked hose, perhaps, my gas cap is not venting correctly? I assume, any extra pressure in the tank may possibly push past the weak spring in the petcock ? Just a thought, and I believe I rebuilt the petcock correctly. Bike was doing good since the rebuild, this just happened yesterday on a day in the upper eighties in temperature. And once again, only did it after the bike sat hot after a twenty mile ride, after approximately twenty minutes. Previously, if you were to, just say, stop for fuel, or just run in the store for a drink, the bike will start as soon as you just touch the starter switch. Thanks again for all your help, I promise not to take a big hammer to it just yet, I'm just sayin' LOL.

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Erdeniz Umman
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Location: Ankara Turkey
Motorcycle: 2000 GL1500SE

Re: fuel coming out of air vent under fuel door

Post by Erdeniz Umman » Fri Aug 04, 2017 11:08 am

hotwire wrote:
Fri Aug 04, 2017 10:56 am
Thanks for the replies, guys. I failed to mention that when I remove the gas cap, there seems to be a lot of pressure building up in the fuel tank, so I guess my next question is: Is it possible along with a kinked hose, perhaps, my gas cap is not venting correctly? I assume, any extra pressure in the tank may possibly push past the weak spring in the petcock ? Just a thought, and I believe I rebuilt the petcock correctly. Bike was doing good since the rebuild, this just happened yesterday on a day in the upper eighties in temperature. And once again, only did it after the bike sat hot after a twenty mile ride, after approximately twenty minutes. Previously, if you were to, just say, stop for fuel, or just run in the store for a drink, the bike will start as soon as you just touch the starter switch. Thanks again for all your help, I promise not to take a big hammer to it just yet, I'm just sayin' LOL.
Normally vacuum will develop in the tank rather than pressure, if the fuel cap vent is bad, unless the bike is parked under the sunlight a long time, of course.

Is the fuel cap OEM or aftermarket? Have you cleaned the vents on it?

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ct1500
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Re: fuel coming out of air vent under fuel door

Post by ct1500 » Fri Aug 04, 2017 2:25 pm

Your fuel cap is designed to hold a slight pressure in the fuel tank which is why the whoosh sound when opening the cap, fuel vapors being released. The EPA has mandated this since at least the 1970's, excessive fuel vapors vented to atmosphere not allowed and is covered under the SHED emission rules. You never want a vacuum in your fuel tank which would interfere with fuel flow out of it. As fuel level goes down in tank or fuel cools air must always be allowed to enter the fuel tank and in this case via the cap to prevent the aforementioned vacuum.

Pressure building in tank to the point of flooding your carbs? Not even on the radar unless when you remove the fuel cap are getting sprayed with gas.


This is what I do
Local and need repair help with your 1500, Valkyrie or ST please PM

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