Gas Leaking from Gas Cap

[rewindgy]

Come on - live a little dangerously! Just for sh-ts and gigles - throw an igniter under there and as you roll dwon the highway after overfilling - lighter up!

[Cajunrider]

I fill mine up the neck to about 1/2" from the top with the sidestand down. It's overflowed from the tube once after filling it and parking in the sun for a 2 hour get together lunch in Natchez, MS. I've read that on the California models, the canister behind the left side cover will fill with liquid if the tank is filled past the plate on the neck. Mine has never leaked from the cap though. Liquid hydrocarbons expand big time as they heat up.

[poppy]

Originally Posted by Eagle

Gasoline is leaking from my gas cap on top of the gas tank. It happens when I fill the tank to the top. There is an overflow, but why does the overflow only work once in a while?

Would it just be the rubber gasket requiring replacement or is something else possibly wrong?

Lately, if I fill my tank up to the plate, it will leak after I start riding, usually within a few minutes. Yes, mine will whistle too. I just assume the gasket is bad......I don't know what the "half-moon" is. Anyone care to elaborate on that? Thanks!

[macmac]

In the well near the cap any liguid will drain, but mainely as i understand it it is a water drain. Of course if fuel fills that well it will drain fuel. I have never followed that drain line to see the exit point.

On all but cal bikes the rear tank drain is located at the right rear of the bottom of the tank, which runs directly to just ahead of the rear tire. I don't see that as a problem, since it is dripping, and evaps fast enough. Upon over filling my 01 and 06 a few times i saw drippings, but they amounted to nothing over all.

Once a year i blow out the cap well drain need it or not. I am more concerned about debis and insects blocking that and having something in the tank fail, that I can't get at to fix.

If that should have a o ring I guess mine was never there either. Now i will have to go blow air thru it and find the exit

[coacha]

Todd had a similar problem of a gas leak on the way back from Custer but his was an easy fix...close and lock the gas cap!

[macmac]

It's a revolt I tell ya! Todd, time to break out the Bess!

[rewindgy]

There are 2 drains from the tank - one for the water that accumulates around the cap - it's the front one, and another that drains the fuel overflow - thats the one with the o-ring. I think what happens is when the cap is un-screwed from the tank most times you only see the 2 o-rings for the screws - the one that seems to fall out is the one for the overflow - it seals between the tank and the tapered nozzle on the gas cap. I know on my black bike I thought it had one until I had a really good look! Then I went an looked at my Drifter and since it is red - you had no problem seeing it! Even my old KLR has one!

[blowndodge]

Actually there is a big write up on whistling gas caps that leak someone on these boards. I understand a really impeccably dressed fellow outlined the cause and cure.

[Yellow Jacket]

Here's a picture of the 0-ring in the fuel overflow vent. The yellow arrow is pointing to it. Just to the left of that you can see the tapered nozzle on the cap. This nozzle fits into the opening where the 0-ring is. The opening beneath the arrow is the water drain. I believe it goes to the rubber tube at the front of the tank on the right side.

Theoretically, if expansion causes the gas to rise high enough it will feed up into the cap through the hole in the center of the cap and then through the nozzle into the overflow vent. This vent exits the tank at the back and connects to a rubber tube going down past the oil filter.

[rewindgy]

You got it Yellowjacket! I don't have any pictures - but if the cap vents properly - and the o-ring is missing or damaged - when overfilled the gas expands, goes up thru the cap and instead of dumping directly thru to the overflow vent tube it exits around the cap and since the drain is slightly higher a lot will puke down the top of the tank onto your lap.

[Idaho]

This thread is handy. I have noticed lately that the o-ring that Bob described above has become disloged and damaged on my bike. I keep trying to re-position it to no avail. Last trip this week coming home from Boise I had fuel running out under the cap and I did not overfill the tank. I remembered this thread and went looking. Looks like a trip to the dealer for a new o-ring is in order.

[Idaho]

What we have described here as an O ring really isn't. I looks more like a top hat with a hole in the middle. It is installed by removing the two phillips head screws that hold the gas cap on.

Dealer did not have one available so we ordered it. He dug through his o-ring kit and came up with two small o-rings that will fit inside the hole of the top hat and I have the very top of the seal ( the hat ). A little bit of super glue held everything together and keeps gasoline from leaking until the new seal arrives.

[AlabamaNomadRider]

Also remember when you fill the bike on the side stand to a certain level, once the bike is in an upright position it will be higher than what you could see before. So if you fill to a quarter inch above the plate in the filler neck once you have the bike upright it will be almost an inch above the plate.

[rcooksey]

I had this same problem last year with my bike. I took off my seat to install tank chap and noticed that one of the tubes that run to the right of the tank (under the very front of seat) was pinched a little from having the seat off one other time check this out it sure saved alot of bad words at gas station! Now I can filler up to the very top of cap and nothing comes out..