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High pressure in the gas tank.

When I remove the gas cap from my 1994 Toyota Corolla wagon, a lot of gas if released. It seems like the gas tank has a lot of pressure in it. Also, I just had a crack repaired in the gas tank. The crack was not caused from being damaged but I suspect from expansion and contraction. Are there valves that relieve pressure in the gas tank? Where do the gas fumes go if they are released? Do they go into the carbon canister? What controls the pressure and the release of pressure? Is this a dangerous problem? I am afraid my tank will crack again and leak gas onto the exhaust pipe causing a fire.

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  • dr_dean_yon Jan 23, 2009

    I spoke to the Toyota Parts department and they told me the gas cap will allow air in but will not allow air out to relieve pressure in the gas tank. They said the fuel system is a closed system. They said replacing the gas cap would not solve the problem of pressure build-up in the gas tank.



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This is common on newer cars it is a positive pressure system if it doesnt have pressure then you have a leak in the fuel system thanks and hopes this helps

Posted on Jan 23, 2009

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You need to get a replacement gas cap

Posted on Jan 23, 2009

  • Roberta Smith
    Roberta Smith Jan 23, 2009

    I stand somewhat corrected... there is a vent pipe that runs parallel to the filler pipe... it is possibly plugged or the hose has collapsed... it is easily replaced from under the car.


  • Roberta Smith
    Roberta Smith Jan 23, 2009

    i did realize my error and have offered you a better solution



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Best bet is to replace gas tank. It could hae a hairline fracture somewhere. Sounds like pretty much everything else was replaced already.

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