Fuel Leaking Under Braking

[mmattockx]

The bike is an 82 1100E. With a full tank (filled to within 1/2" or so of the filler neck) I will get fuel spilling out from around the gas cap under moderate braking. Not full-on emergency stops, just the typical braking during spirited street riding. The gas cap looks ok, it locks down solidly and the seal is in good shape. It looks like the fuel is getting out through vent holes in the cap. I have never had another bike dump fuel like this and it is a nuisance, especially with a tank bag in place. Is this normal or is there something amiss that I can fix to correct it?


Mark

[hannibal]

Any chance of a pin hole leak near the filler neck/gas cap? I had some rice grain sized holes open up after cleaning out the rust.

[mmattockx]

Any chance of a pin hole leak near the filler neck/gas cap? I had some rice grain sized holes open up after cleaning out the rust.

I didn't see anything but will take a better look with a light this evening.


Mark

[argonsagas]

I didn't see anything but will take a better look with a light this evening.


Mark

Simple way to check that is after dark. Wrap a small but bright flashlight with dark green garbage bag until it is thick enough to fully fit the fill opening, place the lens end into the tank and be sure if fits snugly, then turn it on.

The light will reflect back to the top of the tank, and should peek out if any pin holes are present.

[chuck hahn]

Take the black plastic cover off the inside of the cap and youll see an oring that seals the lock cylinder from the tank. If its bad youll get leakage mostly from around the lock cylinder.

[mmattockx]

Simple way to check that is after dark. Wrap a small but bright flashlight with dark green garbage bag until it is thick enough to fully fit the fill opening, place the lens end into the tank and be sure if fits snugly, then turn it on.

The light will reflect back to the top of the tank, and should peek out if any pin holes are present.

I will give this a shot today or tomorrow as time allows.

Take the black plastic cover off the inside of the cap and youll see an oring that seals the lock cylinder from the tank. If its bad youll get leakage mostly from around the lock cylinder.

Chuck, you may have the winner here. There is definitely gas residue on the lock cylinder and around it on the cap. I will have a look at that o-ring as soon as I can.


Thanks to all for the help with this,
Mark

[chuck hahn]

I have looked far and wide for the OEM part number for that oring and still havent found it. I went to Harbor freight and got thier metric oring assortment for like $2.50 and used the closest one they had. Little tight fitting and it makes the turning of the key a bit heavier...but some grease and it seemed to stop my leakage.

Anyone with the OEM number for the lock cylinder oring please feel free to share.