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HELP!!! over filled!

Discussion in 'Gen 2 Prius Technical Discussion' started by lohikaarme, Jul 21, 2008.

  1. lohikaarme

    lohikaarme Active Member

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    I was not topping off or anything!
    I think the sensor in the gas pump failed, I was filling (I was 1 bar below half a tank) and I saw I had pumped 8 gallons in- Nothing clicked off or anything but I said this has to be way too much! and when I pulled the pump out, I heard some gurgling and then quite a bit of gas spewed out.

    I went for an "aggressive" drive to try and burn some gas but I cant bring it down to less than 51mpg so I doubt I burned much despite going 24 miles :(

    I also left the gas cap off for the moment to reduce the pressure on the bladder.

    HELP! this was only my second tank of gas. How do I know if I did damage? what do I do??
     
    #1 lohikaarme, Jul 21, 2008
  2. V8Cobrakid

    V8Cobrakid Green Handyman

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    count your gallons more often at the pump. i try to stop around 10. if i go over, i'll click on the pump and let it sit for a while. that gives the pump's vapor recapture system a chance to let the pressure off the tank.

    or.. pull it out the nozzle then shove it back in.

    your car should send a "feed" (not sure if it's mechanical or pressure related.. even though i've seen the diagrams) back to the filler nozzle so it knows when your car if full.

    Maybe you're having a problem with your tank assembly or tube. it's not a simple system. there are a hand full of things going on when you fill up.
     
    #2 V8Cobrakid, Jul 21, 2008
  3. lohikaarme

    lohikaarme Active Member

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    I am just worried I did some damage- this was the second time I filled but the first time for this station. The first time I filled it clicked off like normal so I am thinking it is more the station than my tank.

    I read some posts on here- I did not get the check engine light and my car seemed perfectly normal after so I did not do damage right away it seems that others have in the past. The fillup was at about 3pm after 90 degree weather all day so I am hoping I wont have a pressure issue as things warm up and I will put at least another 18-20 miles on it before I get home.

    Also, will leaving the gas cap loose help prevent damage in an overfill like this?
     
    #3 lohikaarme, Jul 21, 2008
  4. F8L

    F8L Protecting Habitat & AG Lands

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    Same thing happened to me and I did something similar to you to try and avoid damage.

    It's been a couple weeks now and a couple tanks later I'm not getting any dash lights indicating damage. Milage is the same and everything seems fine. I would recommend putting your gas cap back on though. I only drove like that for a couple blocks before putting it back on securely. :)
     
    #4 F8L, Jul 21, 2008
  5. lohikaarme

    lohikaarme Active Member

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    oooh. well I had the gas cap on while I drove the 24 miles. But now that my lunch break is over and I am back at work- knowing my tank is still over filled, I just removed the cap so that as it sits the pressure cant build in the tank. My HOPE is that if is it going to attack the carbon canister (that is has for others) with the cap off and the pressure free from the system, the gas will leave via the air from the fill point rather than vaporize and increase the pressure on the bladder.

    When I drive home I will secure it again and then maybe do the same thing when I get home for the next 2 days until I know the gas level is back at the normal level. Is this a bad approach?
     
    #5 lohikaarme, Jul 21, 2008
  6. Patrick Wong

    Patrick Wong DIY Enthusiast

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    It was good that you tried to burn off some of the excess fuel in your tank. It sounds like you have used 1/2 gallon so far after refueling, so no worries. Hopefully there is now enough headroom in the event that your fuel expands in the hot weather.

    At this time there's probably no need to leave the fuel cap off.
     
    #6 Patrick Wong, Jul 21, 2008
  7. edthefox5

    edthefox5 Senior Member

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    After that spill she overfilled no mo so driving around to waste gas was a waste of gas. I bet it belched out at least a gallon anyway.
    In 10,000 miles only happened once to me. The belching. Its happened to just about everybody.I bet you get right out of the car and fill it right up.I did too. Its not the station. Its not the pump.Its trapped air in the gas tank. Since i started letting the tank vent it has not happened since.
    Your car is fine.
    Try this. When you go to get gas next time pull up to the pump...open the gas fill cap on the car..go inside and get something to drink...dawdle
    a little. Let the gas tank air a little. Then put the pump in and start pumping.You will have no more problems.
    I also track the mileage per fill up. After getting a full tank of gas I reset the MFD & trip odo so I don't watch the gas pips I watch mileage. At 375 miles its time for refuel no matter what the pips say. It should take around 8 gallons. On mine thats usually 2 pips showing as I av 47-48 mpg's. Anything more than 8 gallons I know is not right. And slow fill only.Good luck & relax. Your freakin'.
     
    #7 edthefox5, Jul 21, 2008
  8. jchristian84

    jchristian84 New Member

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    You're fine, don't worry about it. Galaxee posted on this subject before. As long as everything else appears Kosher you're good (no leaks, gas mileage okay, no warning lights).
     
    #8 jchristian84, Jul 21, 2008
  9. David Beale

    David Beale Senior Member

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    If you can't see fuel in the filler neck you didn't "overfill". As posted above, you had a gas pressure event, where the air being displaced by the fuel couldn't get out fast enough. Try pumping more slowly. I let the vapour out as I fill by pressing the nossle toward the ground (leaving a slight gap at the top of the nossle). As long as you are about 2 quarts below seeing fuel in the filler neck you should be fine.

    The "damage" caused by overfilling happens -after- you completely fill the tank, as you perhaps surmised as you tried to burn off the excess. What happens is the fuel expands as it warms up (underground tanks are at 50-60F). Total expansion worst case would be about 1-2 litres. If there is no gas pocket for this expansion to fill it will press hard on the bladder (liquids don't, for the most part, compress), forcing it into nooks and crannies in the metal tank, possibly tearing it. It may also damage some of the hoses in the tank (the carbon canister is in there along with the vapour recovery system and the fuel pump).

    Then you get gas between the bladder and the tank. The car checks for leaks in the bladder once every so many starts (I think it was around 3-5). If it finds a leak it will set a MIL (check engine light, problem light, or whatever you want to call it). The service tech can then read the code to see what the problem is.

    As posted above, most of us have overfilled at least once. I've done it three times now. Once because I was tempting fate, the other two times it was bad nossles. The damaged tank incidence is pretty low, so its not as easy to initiate as some might have you believe. If you intentionally fill to the brim every time, it's probably inevitable, otherwise don't worry about it.
     
    #9 David Beale, Jul 22, 2008
  10. V8Cobrakid

    V8Cobrakid Green Handyman

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    you do keep your car OFF while refueling... right?

    it's not designed to be refueled while being on...
     
    #10 V8Cobrakid, Jul 23, 2008
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