I have had a gas leak several times but never caught in the act until today, it is coming directly out of the gas cap. How can that be? I drove the truck yesterday, it hasn't been driven today. I went outside and gas was just running down the truck, a lot of gas. I see the air tube coming from the tank to the filler neck, I would assume that would relieve pressure. Is there something there that can cause this? A valve or something? Thanks, Jason.

 

How well does the truck run???

 

What kind of truck do you have also???

 

Oh sorry, I have an 82 4x4 SR5 longbed Pickup truck with 22r engine. The truck is stock.
It runs just fine. It does seem to be lean upon cold starts as it falls on it's face if you push the gas much, but I figured I needed to adjust the carb for that. The gas leaking from the cap has been going for about a year, once every 3 months or so.

 

Weird, does it relate to temperture at all? Or how long you have been driving?

 

The fuel tank should have 3 lines coming out the top, 2 are together coming out of the sender unit (round cover plate with screws holding it on) one is the fuel feed, one is the fuel return, towards the front of the tank on top is another line by itself, thats the vent line, has a hose that goes to a charcol canister thats mounted under the hood, the line may be kinked, the canister may be plugged, etc, but with a non vented cap the tank needs to be vented.

 

This has only happend a few times and the truck had been sitting for at least a night when this happens. This last time it was the previous day, and average temp. I don't remember the other times as it was a while ago.
Ok, so I will look at that vent line and check it out. And the canister. As a backup plan is it possible to put a vented cap on?