Gas tank not breathing

huvin

Original poster
Member
Jun 12, 2013
7
My 2002 trailblazer gas tank isn't breathing and I'd like to know if there's a breather that i could take a look at. I have problems filling up the tank at gas pumps. after an hour or 2 of driving, I remove the gas cap and a big gush of air comes out. anyone know what the problem might be?
 

Mooseman

Moderator
Dec 4, 2011
25,483
Ottawa, ON
There is a pressure relief valve in the gas cap for when there is excessive pressure so the amount of pressure is probably not beyond the capability of the tank to withstand it. But there is the tank vapor recovery system (or whatever it's called) which usually pulls a slight vacuum from the tank. If something is not working with that system, it should give a code and light the check engine light. Did you check with a code reader for any codes?
 

huvin

Original poster
Member
Jun 12, 2013
7
I've got no code readers around.
I don't have the slightest clue what might be causing this
I'm willing to drill a vent hole on my gas tank if that's the only way lol
 

AtlWrk

Member
Dec 6, 2011
674
Please don't drill into your gas tank:redface:

This immediately points me to a clogged or stuck closed "EVAP CANISTER VENT SOLENOID VALVE
". This valve is normally open to allow the gas tank to vent through the evap canister and only exists to close and seal the system to check for leaks. If it's staying closed it's sealing your tank when it shouldn't be.

It sits behind and near the top of the gas tank. Relatively inexpensive and easy to change. You could always pull the hose off of it for a little while and see if the gushing/fill-up problem stops. But if you have to crawl under there to do that you might as well just swap it out IMO.

Word of caution: there are two "evap" system valves. Make sure you get the VENT valve and not the purge valve. I've seen a lot of websites and stores get them confused.
 

huvin

Original poster
Member
Jun 12, 2013
7
View attachment 28841
Is this what you're talking about?

This thing was mounted on the Rear upper right of the gas tank, Pulled a 2 pin connector and a line. opened it up and tons of dirt come out.
I can't test it out at the pumps yet, waiting to receive a new catalytic converter to install.
 

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