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Filler pipe noise when going to fill up.

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by RAV52202, Jan 6, 2013.

  1. RAV52202

    RAV52202 New Member

    I have a 2002 GMC 2500 and when I stop at the gas station to fill up, I take the gas cap off and it sounds like it is pressurized. Any idea what that can be.
    SOunds to me like the system is not venting. If i shut the truck off for a while it wont do it. Is there a venting switch or something thats crapped out?
    Thanks for any help.
  2. j cat

    j cat Active Member 1000 Posts

    your vehicle has pressure / vacuum testing controlled and monitored by the PCM. If you have a problem the check engine light will come on.

    it is possible that the temp changes of the current weather will cause great amount of expansion of the fuel. a check you could do is remove the venting line at the charcoal canister for black residue. this would indicate that you have put so much fuel in the tank that it expanded so much liquid fuel entered the canister that then causes the canister to get damaged and plugged up..

    lets say you fill up then drive a short distance home to your heated garage.. this is the perfect reason all this can occur.. canister is expensive.

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