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Fuel gague

Discussion in 'Gen 2 Prius Main Forum' started by Jalrok, May 12, 2017.

  1. Jalrok

    Jalrok New Member

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    I just did the first fill up on my new-to-me 06 and I've got a question about the fuel gauge. I've been reading a lot about how the tank is actually a bladder on these models. Does that mean that the gauge is non-linear? The computer was reporting about 42mpg, and assuming a tank size of 11.9g I would expect ~500miles. However I was around 325 and the gauge only had two pips left. I went ahead and filled it and it stopped at 7.4 gallons. Based on my expected total, 7.4 sounds right as that matches the computed mpg... but that would mean the gauge seems lower than expected based on the remaining fuel. Should I just push it farther anyway? I've read that running out of gas is really bad for the synergy drive.
     
    #1 Jalrok, May 12, 2017
  2. bisco

    bisco cookie crumbler

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    guess gauge. it only means that what you are experiencing is your own reality.:cool: there is a way to recalibrate the gauge, but it will always be a guess gauge.
    running out of fuel won't hurt anything, as long as you have 3 gallons available in a can with a long slim spout.
    the only thing on an old prius is, if the hybrid battery is weak, and you run out of fuel, then decide to drive on electric until you run out, it could damage your battery.
     
    #2 bisco, May 12, 2017
    Last edited: May 12, 2017
  3. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    The gauge is more a guideline than a rule.
    )
    If you are driving with your Mother in Law, get gas at 3 pips. Running out is something that would ruin your life.
    If you are driving with your spouse, get gas at 2 pips. They will only bring it up for 5 years or so.
    If you are driving solo and can walk multiple times* to the gas station, be brave and get gas at 1 pip.
    Should that pip start blinking, get gas NOW! (I once drove over 30 miles blinking, but once only 7 miles and had to walk, you just can't predict)

    *the computer will not recognize less than 3 gallons between attempts. You can add 2 gallons 5 times and it will still think it is empty. You need at least 3 gallons added before you attempt to start.
     
    #3 JimboPalmer, May 12, 2017
  4. davids45

    davids45 Active Member

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    G'day,
    My experience is that fuel gauges are not linear, despite the pips suggesting linearity.

    In my 10-pipped 2016 Prius c on a long trip in the country, I get about 120+ km for the first pip, about 100 for the second, about 90 for the third, 85 for the fourth, and so on, decreasing down to the last pip with the second last pip being only about 70km.
    The pip average is near 80km per pip which matches the 'consistent' fuel usage of about 4.4L/100km.

    Refilling usually suggests about 5L left (~1gallon) as the "Empty" response point in its 36L capacity tank.

    This is the same fuel gauge behaviour I've had in my previous cars (Echo, Tarago (an 8-seater people-mover)) as well as the Yaris we still have. I don't think the tanks were or are inverted cones. It may be the way the 'depth gauge/sensor' is calibrated.

    I'd think it is normal for other makes/makers as well - been many years since I had a non-Toyota so this is just a vague recollection of last century cars.

    David S.
     
    #4 davids45, May 14, 2017
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