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Gas gauge reads less in the morning than when I left it the night before

Discussion in 'Gen 3 Prius Main Forum' started by Slugdoc, Mar 22, 2012.

  1. Slugdoc

    Slugdoc New Member

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    I imagine it's due to evaporation that happens overnight...
    Is it?

    And if so, would I save gas by filling it up more frequently? (Less room for the gas to evaporate into if I keep the tank more full)
     
    #1 Slugdoc, Mar 22, 2012
  2. sdtundra

    sdtundra Senior Member

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    Are your temperatures fluctuating? My guess is that it's due to the "bladder" in the gas tank expanding and contracting with the temperature changes. There shouldn't be any evaporation going on into the outside air as that is a violation of EPA regulations.
     
    #2 sdtundra, Mar 22, 2012
  3. royvogel

    royvogel TanzMan

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    How about the air temp? Gas expands when warm and contracts when cold. Indy cars use liquid nitrogen (-325f) to cool their fuel before filling up for the race!
     
    #3 royvogel, Mar 22, 2012
  4. Slugdoc

    Slugdoc New Member

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    No Bladder in the 2011, as I understand it.

    Not talking about evap to the outside. Rather - within the closed feul tank, there will be liquid fuel in equilibrium with gaseous fuel. THe more empty space in the tank, the more gaseuos fuel, relatively.

    It is cooler in the morning. That could be it.
     
    #4 Slugdoc, Mar 22, 2012
  5. spiderman

    spiderman wretched

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    If anything, mine adds a pip from the night before.
     
    #5 spiderman, Mar 22, 2012
  6. qbee42

    qbee42 My other car is a boat

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    The Gen III Prius does not have a fuel bladder. The bladder was used only on the Gen II NA models.

    Modern fuel systems are sealed to prevent evaporative losses. The one on your Prius self tests at night; any leak would throw a code, causing a warning light on the dash.

    Fuel gauges in cars are not precision instruments, so don't expect precise readings. They are also damped, so you won't see quick variations. My guess is that your parking situation introduces some variation in the displayed level, but there isn't enough time for it to react when you pull in to park. Starting the next day you see the variation.

    Tom
     
    #6 qbee42, Mar 22, 2012
  7. p00kienrayray

    p00kienrayray Active Member

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    Maybe someone is taking your car for a spin while you're asleep?:D
     
    #7 p00kienrayray, Mar 22, 2012
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