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Gas tank overflows when filling

I have a 2008 Hyundai Sonata that overflows at most gas stations when filling. To fill the tank, I set the pump on autofill and walk away. The pump clicks off and then the car "burps" and gas comes out the filler neck and runs down the outside of the car and out the bottom. It does not do this at one gas station by my house but seems to at all others almost every time. The car is still under warranty (42,000 miles but the issue started at 29,000) and I have brought it to the dealer 3 times. Each time they claim to have found something new wrong and fix. The first time they replaced the fuel filler neck, 2nd time fuel filler neck assembly (and tested at a gas station and it worked), 3rd time the vent valve. Each time I try it and it overflows for me (except at that one gas station). I have never had this issue before with any other car including my wife's current car.



I'm truly stumped, but feel that a car should be able to fill up at a gas pump without overflowing.
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Comments

  • edited January 2011
    I believe the vapor recovery system on this car is having issues. All '96 and newer cars are suppose to capture fumes released by refilling through the evap system to prevent these fumes from getting into the atmosphere. Gas station nozzles also are supposed to do this with those funky nozzle covers they added over a decade ago. If the vapor recovery system of all but one of those stations cannot keep up with the exchange of air, you get a pressure build-up and spillage.

    I've had problems like this at a few gas stations that I believe had inoperative vapor recovery equipment. My fix was to pull the nozzle out just enough to allow a small gap between the funky nozzle cover and filler neck. It allows the tank to vent as new gas goes in, preventing pressure build-up.
  • edited January 2011
    I set the pump on autofill and walk away.

    Illegal in most places and unsafe in all. When you are pumping gas, do not leave the pump! Yea, it happens, I use to live across the street from a station and I remember two fires. Lucky only one minor injury, but the possibility of more.

    Are you in the habit of topping off the tank when you "fill" it? If so that is likely the problem. Your vent system (vapor recovery) may be damaged because you have topped it off one too many times.
  • edited January 2011
    Let me clarify to the last poster. I don't walk away...I step away so I'm not standing directly next to the car breathing in the vapors. I'm normally standing just to the rear of the vehicle watching how many gallons. Also, I never top off the tank as it says not to. When the auto pump shuts off, I take the pump out and drive off.

    Thank you for the suggestion BustedKnuckles.
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