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Discussion in 'Gen 2 Prius Fuel Economy' started by melissaK, Oct 22, 2009.

  1. melissaK

    melissaK New Member

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    I put about 8 gallons into my new 2008 Prius today (just got it three weeks ago), and I drove about 110 miles straight from fill-up, and my gas gauge is still on the F. It's just a bit nerve-wrecking to me, as in, I'm worried I broke the gauge. Is my mileage supposed to be high enough for it to stay on the F that long, or should I be contacting my dealer? I coasted on my electric motor a ton, but still, it's nerve-wrecking. I'm a 20 year old f that knows nothing about cars, and I'm still trying to understand how this all works. Please please help.
     
  2. philobeddoe

    philobeddoe ΜΟΛΩΝ ΛΑΒΕ

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    are you being serious?
    what is your indicated mpg?

    try to relax, there's plenty other things to be worried about. it sounds like you're doing just fine.

    no, don't call the dealer, they'll take you for a simp and sell you a bridge.

    if you're really that worried, talk to you doctor about a prescription.

    relax, take a hot bath, you'll feel much better in the morning :thumb:
     
  3. firepa63

    firepa63 Former Prius Owner

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    I've driven 185 miles before the first pip disappeared on occasion and also as little as 65 miles. Don't worry about it. It's the bladder in the fuel tank that makes it do strange things.
     
  4. Benggolf

    Benggolf Member

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    You are getting great fuel mileage already! ;)

    On a serious note, that is pretty normal especially if you topped off your gas tank and are light-footed. Don't expect the fuel gauge to move anytime until after 120 to 150 miles.
     
  5. uart

    uart Senior Member

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    For me the first pip on the gauge is equal to about 3 of the other pips, it's a veritable mega-pip :p. Relax, it's totally normal to go that far on just the first pip.
     
  6. Sandy

    Sandy Hippi Chick

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    oh it never gos down you however can borrow my RX8 and watch it move from the fillup.
    I get sometime 120-150 before the first dash disappears.
     
  7. qbee42

    qbee42 My other car is a boat

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    Most gas gauges, the Prius included, have a dead band at the top. The fuel level drops for awhile before the gauge starts to move down.

    Tom
     
  8. Celtic Blue

    Celtic Blue New Member

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    Tom is mostly correct. However, the digital gauge in the Prius is a pain in the nice person because unlike analog gauges it can't show changes in this "overfull" band. The analogs generally will show some response in the top end unless they are pegged well above Full, whereas the Prius digital won't show any change until it drops to ~90% indicated. Since a normal gauge will display a range of about -25% to about 125%, being unable to see a large percentage of the tank's capacity is the bane of the Prius guess gauge system. The flashing pip starts at ~12.5% (~1/8th tank indicated.)
     
  9. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    very common occurrence especially at this time of year. if you filled up your tank and then shortly afterward, the weather turned colder, you tank will appear full longer than normal. trust me, this is temporary unfortunately.
     
  10. qbee42

    qbee42 My other car is a boat

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    Most of the analog gauges I've used pegged at full. Likewise some of the analog systems have discrete senders, so you get a banded response even with an analog gauge. It's a frustrating situation, and also helps explain why pilots calculate remaining fuel rather than relying on gauges.

    The fuel gauges on the Gen II Prius are less consistent than most. Never expect to know exactly how much usable fuel remains in the tank, unless you enjoy walking.

    Tom
     
  11. Bobsprius

    Bobsprius BobPrius

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    Melissa We are Neighbors! Private Message me...well we live in the same area at least...Buffalo is not that big!

    Your fine I am sure, The guage sometimes takes a while to move. You should be fine...they move faster as you the miles go, so you should see it move soon.

    But Private Message me and I would love to share Stories and we can meet and share GEN III and GEN II comparisons...If you wish. ;)
     
  12. Celtic Blue

    Celtic Blue New Member

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    Interesting. Most of mine have not. They have seemed to peg at times, but well past full (e.g. my current Tundra which displays about three gallons above full.) I could watch them work their way down toward the full indication and I've used it as a way to determine what fill angle gave the best fill to reduce variability.

    Same has been true on the bottom end where the E hash mark is typically about where one would expect the 1/8th tank indication to be. The needle keeps on dropping from there...I'm not sure that I ever saw it stop, despite having run the tanks of my previous three vehicles down very close to total stated capacity. Never ran out doing this over about 500,000+ miles.

    There is a hysteresis effect that is apparent on cold starts on other vehicles. I don't know if it is intentional, but they tend to display lower for the first few minutes before working up, then back down as fuel is consumed.

    The GenII's bladder and digital display make this sort of resolution and accuracy impossible. It's too bad the digital gauge isn't a simple numeric indication with the 2.5% increments of the output. That would be far more useful than driving 200 miles with no change in gauge indication...
     
  13. hobbit

    hobbit Senior Member

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    I think my own standing record is 220 miles before dropping the
    first pip, from one of those times a faulty pump nozzle almost
    gave me a "squirt event" but I caught it in time and still wound
    up with a very full tank.
    .
    _H*
     
  14. qbee42

    qbee42 My other car is a boat

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    Shawn, I think the hysteresis effect is really a time constant built into the metering system to dampen oscillations - probably nothing more than an RC circuit. Otherwise the fuel gauge would swing up and down around corners and hills. On power up, the dampening circuit charges, so the indicator slowly rises.

    I don't doubt that your old analog fuel gauges worked differently than the ones I had. There seems to be a lot of variation in how they are built. I've had some pretty bad ones over the years, and some that were quite good.

    On some of the old fuel gauge displays you can see a small overlay piece at the Empty position of the gauge. This piece was attached separately so that Empty would be correctly calibrated. Apparently it was cheaper to glue the piece on in the right place than build a trimmer into the gauge.

    Tom
     
  15. Son of Gloin

    Son of Gloin Active Member

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    As others have suggested ... this is rather normal and no cause for alarm.

    After filling up Mithril, our '08, "he" almost always travels at least 100 miles before the first pip goes out.

    The longest he's gone with all 10 pips still on is about 175 miles.
     
  16. JimN

    JimN Let the games begin!

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    Welcome to the "Guess Gauge". The only time it is accurate is at empty. Tonight I went from 2 pips to 1 pip by booting up the car.
     
  17. luvmypriusbutnotinthesnow

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    I went from Bend, OR to Castle Rock, WA and the gauge was still showing full. 2-1/2 hour drive. In Bend however my son was fueling up while I was taking a leak, and when I came out fuel was every where. We do have trouble at times with filling up.
     
  18. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    ^^ +1

    You'll feel better, be well rested, and squeaky clean.

    On a side note: Welcome to PriusChat!! :welcome:
     
  19. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    i have only seen it once or twice in my 04 or 06, but have already seen it several times on the 2010, where i will "grow" a pip overnight. i will frequently shutdown with 8 pips only to have 9 the next morning.
     
  20. zonie911

    zonie911 Member

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    Melissa. Welcome to PriusChat. Read all you can about the gen ll Prius, which is what your car ('08) and mine ('09) is. Read all the threads about the gas tank being a "bladder" type, which is nothing to be frightened of nor alarmed about. You just need to think about the tank a little differently. The pip data you've mentioned is totally normal.

    Just research the threads about allowing the tank to breath to prevent overflow when filling up and I never allow my tank to go below 4 pips left to fill-up, as the bladder will shrink some and will need to be allowed time and pressure to expand again.
    But, no problem, just a heads up on my experience with this.
    Read all the threads on the gen ll forum for information.
    Knowledge is POWER.
    zonie