2009 PRIUS GAS TANK WONT FILL

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by PriusNYC96, Dec 13, 2019.

  1. PriusNYC96

    PriusNYC96 Junior Member

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    Hi. I have a 2009 Prius and my gas tank won't fill to max. I go to the gas station to fill up the tank when it gets to empty and it will only take 6 gallons of fuel and it will say that it's full but the gas tank capacity is 11.9 gallons. I should still be able to put another 6 gallons in it but I can't.

    Then I will get about 250 miles from that fill up averaging about 50 miles per gallon. The car seems to be working fine it's just that the gas tank won't fill up all the way.

    What should I do?

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  2. PriusCamper

    PriusCamper Senior Member

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    I've never fit more than gallons in the tank, that's normal, due to rubber bladder in tank which is designed to displace less polluted air. Problem with these bladders is some times the don't fully expand in Winter... Keep your tank as full as possible and it will work itself out once the weather warms. Replacing the tank is another option, but likely same problems could return.
     
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  3. TMR-JWAP

    TMR-JWAP Senior Member

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    So how do you know it not full?

    maybe there's still 5 gallons in the tank when you think it's empty...…...
     
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  4. PriusCamper

    PriusCamper Senior Member

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    Pretty sure gas gauge recalibrates if you disconnect 12v for a few minutes...
     
  5. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    The Gen2 in North America, there is a bladder inside the metal 11.9 gallon tank. This bladder changes shape and size with air temperature.

    So if you live where it is hot in summer, you might get 10.5 gallons in it on a July afternoon, and 7 gallons on a winter morning.

    New York will be less.

    My advice is to get gas at two pips, and stay happy.
     
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  6. fuzzy1

    fuzzy1 Senior Member

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    Did you run the fuel tank all the way down until the engine quit running? If not, then the tank wasn't really empty.

    Or did you merely go to the bottom of the fuel gauge, which on a Prius is a single flashing bar? Note that on nearly all cars, the bottom of the gauge is not at the real bottom of the tank. They have some safety margin below Empty, so that unwary drivers have some time to notice, and others can handle the very common instances of higher than average fuel consumption without getting stranded. Short term MPG is far more variable than many drivers realize.

    Beware that some Gen2 Prii can't even make it all the way down to that flashing bar before suffering fuel starvation, thanks to that problematic fuel bladder.

    Does the fuel gauge appear to go all the way to the top? If so, then just keep refilling before you get to the bottom of the gauge, and you will be getting all the usable tank capacity of this problematic bladder. It was a theoretically good idea whose time has still not arrived, so they ditched it and tried something else for emission controls at the next model redesign.

    If the gauge doesn't go all the way to the top, then the pump nozzle may be cutting off early, another common Gen2 bladder issue. Some people just click the nozzle handle several more times, others turn the nozzle sideways or upside down, others fill at a slower than normal rate (e.g. slowest latch point on the nozzle's handle), others wait a minute after opening the fuel cap so the bladder can vent, etc. But these approaches are useful only if your gauge isn't reaching the top.

    But unless you have a habit of running to complete fuel starvation and getting stranded alongside the road, give up on the idea of getting the full advertised tank capacity -- on every car you drive.
     
    #6 fuzzy1, Dec 14, 2019
    Last edited: Dec 15, 2019
  7. dolj

    dolj Senior Member

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    I can vouch for the fact that these symptoms (and fixes) are not attributable to the flexible bladders. Non-NA models do this as well and these fixes work the same.
     
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  8. fuzzy1

    fuzzy1 Senior Member

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    Are Gen2 Prii in NZ worse for this than other cars, including Gen3 Prii?

    Other North American cars can have these problems too, but the Gen2 Prii seem to be much worse, in a class by themselves. I experienced it on a two week rental the year before buying a Gen3 (and before I found PriusChat), and plenty of readers here have commented about it.
     
  9. dolj

    dolj Senior Member

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    I haven't had a lot of other car experience (and no Gen 3 experience) in the last 12 years, so if it is attributable to some aspect of modern emissions controls, I would not really be aware how other cars behave. I can say it has been the same on 4 different Gen 2 Prii with which I have had direct experience and that I have not had the need to take such care and attention re-fuelling other cars I owned or drove before I got the first Prius.
     
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  10. fuzzy1

    fuzzy1 Senior Member

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    It is going to be hard to believe that your non-bladdered Gen2s could be as bad as our bladdered versions, without hearing from drivers with significant experience with both. And there are likely few people fitting that description.

    But it certainly is a useful datapoint to hear that your Gen2s are more troublesome during refueling than are other cars. Perhaps we are overlooking some other important differences between Gen2s and other cars, beyond the obvious and easily blamed bladder.
     
  11. dolj

    dolj Senior Member

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    That's what I'm also wondering.
     
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