low fuel warning with 3 gallons left?

Discussion in 'Gen 2 Prius Fuel Economy' started by astro, Nov 4, 2005.

  1. astro

    astro New Member

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    yesterday, the last bar on the fuel gauge started blinking for the first time (i've had my 2005 prius for about 4 months). thing is, i had only driven about 490 miles with the average mpg showing at over 50 (i think it was 50.5 to 51). when i filled up, only 9 gallons went in. the manual says it has 11.9 gallons.

    so is something wrong with the gauge, is this normal, or is the tank much smaller than i thought?
     
  2. Wayne

    Wayne Active Member

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    One minus about the Prius is it is netoriously hard to fill up. You either don't fill the tank, or it gushes out all over the place. The biggest problem is they have a tight rubber seal where the nozzle goes, and it is just too tight to let air pass properly while you are refueling. I've started getting the hang of it, but I'm still never positive when it is actually FULL.

    So, my guess is, you didn't actually fill the tank.

    And oh by the way, congrats on having a car where you can say "I had ONLY driven about 490 miles..." on a tank! :D
     
  3. Maytrix

    Maytrix New Member

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    Read the other 100's of posts on the subject...

    I could tell you that the fuel tank is a bladder and that it fluctuates and that even if it was bone dry, you'd never get 11.7 gallons in. I could also tell you to forget about trying to get 600 miles on a tank or to just drive and fill it when needed. I could even continue and add that many users try to top off as much as they can, often adding a gallon or more after the shut off. Personally I don't think it matters - I fill it when I have a bar or two and put in until shut off..

    So.. I could tell you all this, but I won't. You'll just have to do a search for it. :rolleyes:
     
  4. hdrygas

    hdrygas New Member

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    You learn to know what pumps do the best job at "filling" the tank, at least until some one "adjusts the overfill cut off" on that pump. It is an issue. Remember as you look at Tank figures that the life time numbers and trends up or down are much more reliable measure of how you are doing with your miles per gallon.
     
  5. driveprius

    driveprius New Member

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    So how much do I panic when my fuel warning light goes off?

    Now I thought I had gotten a nice 47.9 mpg based upon the amount of gas I put in. Now you're telling me instead of putting in 8.7 gallons to fill up my tank I could have actually burned off 3 more gallons and had as little as 35 mpg even thought the computer says 44.8 mpg.

    Originally, I was happy with the idea that I could easily gauge how many miles I have left on my tank by multiplying the current average by 11.9 gallons to get the current expected total miles I am expected to be able to reach since my last refuel until I go bone dry. So if my average is at 45 mpg than I know I'm on track for 535.5 miles total and if my odometer shows me at 430 miles since the last refuel, I know to take it easy as I have a good 105.5 miles left.

    However, if it's not unusual to be 3 gallons off than I have to assume the worst and so at 45 mpg I'm at 430 miles on my odometer, I could have stranded on the road. You see the light didn't start blinking until 430 miles. So if my maximum theorectical distance is 400 miles on a tank that may effectively be a 9 gallon tank then should I panic?

    Does anyone have a good estimate of how many gallons are left when the light starts blinking?

    I really don't have any problem with not being to top out my tank to the very top. I just need consistant fills with accurate estimates of how many miles I have left before I need to see a gas station to avoid getting stranded.
    :eek:
     
  6. tullynoon

    tullynoon New Member

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    When my '05 was new I put a gas can in and intentionally flamed her out - 62.7 miles from blinking pipper. That's now the only indication I use on when to fill the tank and I don't try to get the last drop in since she covered my shoes with gas last month.
     
  7. seasalsa

    seasalsa Active Member

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    The fuel guage is known to be inaccurate but you will not run out of fuel if you plan to fill up with 1 or 2 bars remaining. That said, the guage is not nearly as inacurate as multiplying the current average by 11.9 gallons to get the current expected total miles
     
  8. Wayne

    Wayne Active Member

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    If you under-filled it last time, and then you fill it, your gas mileage for the last trip will appear lower than it was. Look at your overall mileage.
     
  9. FredWB

    FredWB New Member

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    In now have about 18,000 miles on my 2004 Prius. I have never put in over 9 gal in a fillup. My average is 8.2 gal. I never top off but I do set the pump to the lowest auto setting when filling. I always fill up within 10-30 miles of the last blinking bar. Only once did I go to 50 miles after the last bar and I took 9 gal then. I'm pretty used to getting about 400-425 miles per tank. I'm not happy about it but I can't change what I can't change. There might in fact be 3 gals in the tank but I just don't want to test it by running out of gas. The dealer did the two part TSB fix for early Prius like mine and that improved the gage linearity some but not the capacity. All I really got from that was a creaky rattling dashboard. Fill up around 400 miles or at the last flashing bar and you probably won't go wrong.
     
  10. Maytrix

    Maytrix New Member

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    If you really want to be sure as to how much fuel you have left, try this.

    Keep track of every single fill up. Take your last fill up and subtract your most recent. Then add this to the difference from the previous fill up. This will give you an accurate number of gallons you'll be starting with after each fill up.

    Quick Example:

    Gal Left
    10 10
    5 5
    6 4
    3 7
    5 5


    If your fill ups are on the left, then the number on the right is how many gallons you'd have available after each fill up. Ideally, to get the best results, you'd have to get it as close to empty as possible and then fill it as much as possible. With this method, you'll at least know the minimum gallons you have.
     
  11. genalex

    genalex Member

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    :eek: Poor baby!
    Us Jersey guys lol at the other 48 state folks who have been screwed by the oil barons into pumping their own gas. We have lots of jobs for gas jockeys who need them, sit comfortably in our cars (with dry shoes) and still have the cheapest gas prices around.
     
  12. bkmcae

    bkmcae New Member

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    I had a weird fill up last week.

    Blinky appeared. I immediately drove to the gas station and put in just over one gallon (gas is more expensive by the office). Blinky stayed around, even through my whole drive home.
     
  13. tumbleweed

    tumbleweed Senior Member

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    We have the same thing in Oregon (we are not allowed to pump our own gas) but our prices are higher than any of the neighboring states. I'll admit that sometimes it's nice just to sit in a warm car while somone else pumps my gas, that is until they spill it all over the fender because they don't know about the stupid fuel bladder. Oh well, at least I can laugh at them when they get on their shoes. :D
     
  14. skruse

    skruse Senior Member

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    Based on many posts, I fill up when the last bar is blinking. Generally I can put in 10 gal. No throw-up. Using a 10.0 gal fill-up makes it easier to calculate mpg. I never run out of fuel and avoid any problems associated with running out of fuel.
     
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