Gas Tank Leak when Filling / Check Engine Light due to Vapor Leak" I'm reading these gas tank filling issues on the 04 Avalanche, I've had them too. Now another issue; when you fill the truck and "top it off" (fill it all the way up to the top of the filler receptacle), gas leaks out of the top of the tank. You can't see where it's coming from but it leaks down the driver's side of the gas tank, coming from the top. This strated several months ago with a check engine light that couldn't be cleared (the code on the re-check device says "fuel system vapor leak". You can clear it with the analyzer, but it will come back on and saty on. I'm hoping that the issue is due to the clogged vent selenoid mentioned by Jeremy, and that it's not going to require dropping the tank.

SOURCE: my 97 honda civic dx check engine light keeps coming on

Had this issue did you replace the exhaust

SOURCE: 78 VW camper has Gas leak after filling tank, other side of the

I had the same problem as this. There is a pipe that runs from the petrol tank around and up into the air inlet shaft under the spare wheel well. I am not sure exactly what it does I think it has an expansion valve on it. There is a join in this between two tubes that join. This is a simple piece of fuel tube with an internal dimension of say 5mm. If you feel your hand into that air shaft there, locate the fuel tube feel your way along the pipe, you will find the join. Just pull the old one out and put a new piece in. Very simple. really

Robert

• 51 Answers
• Posted on Dec 03, 2011

SOURCE: GMC Jimmy gas filler neck leak

Replace your filler neck. It's not hard and when you buy the new one, installation should be obvious and rather straight forward.

A fuel leak is not something to take lightly and it will get worse over time.

Most fuel systems are pressurized (that's why you'll sometimes hear a hissing sound when you open your cap) so if your filler neck is leaking it can throw a code.