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Filling gas tank

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18 comments

  • catpealer111
    If you drive a newer GM, not tightening the gas cap enough can cause the check engine light to come on.
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  • beneteau
    I've been told that a loose gas tank cap on some vehicles can activate a service engine light.

    Cat----you beat me to it.
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  • slipgate
    I don't see how overfilling a gas tank could possibly "ruin the sending unit".
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  • Huntingnerd33
    I've always put more gas in after it clicks off and I've never had a problem at all. I think the mechanic was feeding you a line on the $500 repair.
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  • FrancF
    quote:I've been told that a loose gas tank cap on some vehicles can activate a service engine light.
    Yep

    quote: If you drive a newer GM, not tightening the gas cap enough can cause the check engine light to come on.

    Yep


    It's a 50 state Smog standard- for all vehicles.
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  • Cubslover
    Pretty much all 2000 and newer cars will send an "Evap Leak" signal in this case.

    Most of the time, all you have to do is tighten it(of course). Start the car and drive around until it is completely warm. Shut it off and let it cool completely, then drive it until it is warm again, and shut it down until it cools. Do that twice - maybe two days at work? Drive to work - warm, cools while you're at work, drive home- warm. It's cool in the morning......

    The light will clear itself that morning when you start it and it checks all it's systems.
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  • Txs
    Did you leave the engine running while you were gassing up? Removing the gas cap with the engine running causes the check engine light to activate on our Crown Vics at work.
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  • Warpig883
    Our Chevy Lumina does the same thing.

    The owners manual even warns against overfilling. It is emmision related and has to do with blocking the vent in the fill pipe.
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  • sig232
    quote:Originally posted by beneteau
    I've been told that a loose gas tank cap on some vehicles can activate a service engine light.

    Cat----you beat me to it.





    Yep, My Jag computer gives me a read out that says. "gas cap loose"!
    It will not pressurise the tank properly if it is not tight.
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  • Dak To 68
    Get a second opinion before you spend $500.
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  • Frogbert
    quote:Originally posted by Dak To 68
    Get a second opinion before you spend $500.


    +1 Absolutely! Then, report that mechanic for consummer fraud. No telling how many people he is scamming.
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  • idsman75
    Frogbert--Wrong. More than one brand of car will do this. I was warned by my dealer when I bought my car new in 2003. It's bad for the Evap system of a lot of newer cars to overfill. Once the fuel pump stops pumping, stop pumping. Don't try to top it off. It's not good for the Evap system. Also, make sure your gas cap is screwed on tightly. This is not fraud and this is no joke. It's all true. Did you check your owner's manual?
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  • TexasVet
    It used to be when you overfilled the tank, the evaporative system would fill with fuel instead of vapor. The fuel would get into the charcoal cannister and remove charcoal from the walls of the cannister - which would in turn make charcoal pieces get into the fuel lines and injectors. That's why I always fill the tank to the first time the pump clicks when it's full, remove the fuel nozzle and reinstall the fuel cap.
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  • bigtire
    I spent $100 on an error code reader. I have a ten year old Mercedes that frequently flashes the check engine light at me. I got tired of spending $75 for some mechanic to tell me it was this or that, not to worry about it and come back in the next time it happens.
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  • Frogbert
    It won't ruin the sending unit, and if it did, it wouldn't justify a $500.00 fee to fix it.

    The fuel filter prevents any damage from charcoal, which is a far-fetched and unlikely result of a little overfilling. That's all just a crock.

    Go here and learn why your sending unit cannot be harmed in this manner:

    http://auto.howstuffworks.com/fuel-gauge1.htm
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  • Hunter Mag
    Remove the bulb and problem solved with wasting money cause the freaking thing lit up for no reason.
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  • TexasVet
    quote:Originally posted by Frogbert
    It won't ruin the sending unit, and if it did, it wouldn't justify a $500.00 fee to fix it.

    The fuel filter prevents any damage from charcoal, which is a far-fetched and unlikely result of a little overfilling. That's all just a crock.

    Go here and learn why your sending unit cannot be harmed in this manner:

    http://auto.howstuffworks.com/fuel-gauge1.htm


    Frog,

    You're wrong about the fuel filter catching the carbon -- the filters on some cars are in line with the fuel tank, not the evaporative system, which is on the return side. I know of many vehicles (particularly the 80's Dodge Omni's with carbs) that had the problem with the carbon from the charcoal cannister getting into the carb when the fuel tank was overfilled. The problem was so prevalent that Chrysler was nearly sued over it, and they bought back a lot of the cars under lemon law proceedings.

    I have never heard of overfilling a fuel tank and ruining a fuel sending unit.
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  • festus
    This was on a 2002 GMC, he cleared the code and everything is fine so far. No charge, good mechanic i've known for thirty something years. He had one that was bad that he showed me and pointed out what was wrong with, said it was from over filling. Not sure, but looked like the fuel pump and sending unit all made together. Might be why it is so expensive.
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