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Anyone figured out the fuel guage?

Discussion in 'Gen 2 Prius Technical Discussion' started by Bluesguitar, Oct 14, 2008.

  1. Bluesguitar

    Bluesguitar New Member

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    I have a nice 2008 Touring model with about 1300 miles on the clock now. I'm averaging about 46mpg which is great, and it seems like a terrific car except for one thing: I can't figure out how much gas is in the tank!

    Last week I was down to one "bar" and since I'd driven about 400 miles from my last fill up, I figured it was due to be filled. I got about four gallons in, and that was all it would take. I thought it might be an issue with the station's hose or nozzle, so I just decided to leave it be finished the transaction.

    Surprisingly, the guage went all the way up to FULL, but over the next 100 miles came down to half, and then below, and then in less than 300 miles all the way down to the flashing single bar...Meaning that my last fill up was about 7 gallons since I averaged 46 mpg on this tank.

    Back to (a different) gas station-- this time 10 gallons (barely) goes in, again up to FULL.

    Is this just something to live with on these "gas bladder" cars? Seems like a real design flaw to me. I know I'm getting great mileage, but I'm visiting the gas station more than I used to with my "regular" car and that's psychologically challenging!

    Mitch
     
  2. firepa63

    firepa63 Former Prius Owner

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    It's a "guess" gauge. And yes, the bladder will impact the filling of the tank. Try filling slower.
     
  3. qbee42

    qbee42 My other car is a boat

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    There is really nothing to figure out. When it gets down to a couple of bars, get gas if it's convenient. If it gets down to one bar, get gas soon. If it starts flashing, get gas right now.

    It gives you a gross approximation of the contents, and good end of tank information. Don't expect much more.

    Tom
     
  4. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    Hey Mitch,
    One thing that has been proven conclusively is that the amount of gasoline you can fit into the bladder is directly proportional to the ambient temperature. I noticed that you're in Boston. It's been getting into the 40s overnight; is it possible that you got gas in the morning? And this recent tank; is it possible that you got gas in the evening?

    But to answer your question, yes, it's something we all live with. Well, those who live in warmer climates where the bladder is always warm are just a bunch of spoiled little brats and don't count anyway.*

    And welcome to PriusChat! :welcome:

    *this statement is not endorsed by the bratty little warm-climate lovers.
     
  5. Wa1hog

    Wa1hog Old Blind Hippie

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    I also live near Boston. Ive found that the tank fiull ups will vary. I can get 400 Miles on one fillup before the last bar. Other times all I get is in the 350 range. BUT, the fill ups do relate to the milage. I consistantly get 48 to 52MPH. Its the bladder. Kind of what im going through with my bladder now that Im 58!!
     
  6. dwdean

    dwdean Member

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    <sarcasm>
    Yeah, it works alot like one of those Lucky Number wheels, you spin it but have no idea where it'll stop.
    </sarcasm>

    Seriously, the bladder does have alot do with it. But honestly, you do get used to it and you do sort of do rough calculations of how far you should be able to go on the last fill-up.

    No, that's not really good, and is something I hope they learn to address in future versions. For those of us who own Gen II's it's just one of the few things we have to deal with that are truly odd about the car.*

    To Tony....Speaking as one of those people from a warm area, I don't think that "counting" was our specific problem, for the most part we "count" well enough, our problem was determining what to "count". Of course this did lead to some speculation that we in fact didn't know how to "count", but they really were two different problems. Hopefully we won't do that again, but lets try to not jinx it by reminding us of our "couting" issues. ;)

    * If I ever run out of gas in the middle of BFE, because the guess gauge says I had more gas than I really did and I messed up my calculation, I'm liable to sing a different tune.
     
  7. Wa1hog

    Wa1hog Old Blind Hippie

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    All you have to do is when the bars get to two its time to think about filling up with 7 or so gallons of gas.
     
  8. dwdean

    dwdean Member

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    I really subscribe to the method that Tom spelled out, but supplement with that calculation.

    It's really not all that hard, I just find it strange that a car that is otherwise rather precise has a gas gauge that is less predictable than a schizophrenic on acid.

    OK and I couln't resist the temptation of the sarcasm. :cool:
     
  9. EZW1

    EZW1 Active Member

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    There are AZ and LONG sensors that are used to correct the fuel gauge reading. If you fill the tank with less than 8 gals or if you run out and it says you still have fuel remaining, then they will need recalibration. The dealer can do this for you. I posted info about it elsewhere on the forum. Do a search and find it.
     
  10. Goldwingerx2

    Goldwingerx2 New Member

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    We fill when the gauge get to the half way mark. I know I am carrying more weight than needed but it is the comfort thing. We can take off for what ever and not have to worry about getting fuel. I always tried to get across to the kids to do that and I have continued. Not sure where the fuel pump is located on the Prius but I have been told by dealers when the fuel pump is in the tank it runs cooler and lasts longer.
     
  11. Rokeby

    Rokeby Member

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    Mitch,

    you've highlighted one of the great incongruities of this car. It gets twice the
    FE/MPGs of most cars, three or four times that of SUVs, yet you go to the
    gas station just as often.

    Well, you pretty quickly figure out it's the combination of a small gas tank,
    with erratic reductions caused by the tank bladder. You just have to live with
    it.

    The other day I saw a neighbor at a nearby gas station. He drives an
    Explorer. When he sees me he says, "So what's up with the little car, didn't I
    see you here last week?" I admitted we had crossed paths last week as well,
    and then redirected the conversation as the tank filled. It turned out we both
    drove out the same number of miles between fill-ups.

    The nozzle clicked off, and I said, "Hey, look at this!" pointing to the pump
    which read ~$26.00. He looked at the numbers, then at me, then the car,
    then his Explorer, then back at the numbers.

    Shaking his head, he said, "I can see why you like that little car." -- Priceless!!
     
  12. Fritzenheimer

    Fritzenheimer New Member

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    We just purchased a new 2008 black #6 in September and have driven about 1300 miles. Recently, we took a few trips back and forth to Lagrange about 75 miles from home. The first trip was in the midst of Atlanta's recent gas shortage and when we got to Lagrange we took advantage of finding gas and put 2.5 gallons in the tank. The gauge registered full.

    We returned to Lagrange about a week later and had traveled about 200 miles when we stopped for gas again. The gauge registered about 2 pips down from full. I was surprised that the tank took 5.7 gallons when according to the MFD we were getting over 53 mpg.

    After filling up we drove over 200 miles and the gauge was still registering full! With about 300 miles on the tank we were only down one pip! Nervous that the gauge wasn't operating properly, I took the car to the local Toyota dealer and asked them to check it. The technician told me he reset the inclinator and recalibrated the gauge, and it dropped one more pip. So now we've got over 300 miles on the tank and are still down only two pips.

    The technician told me if that didn't correct the problem I could bring the car back and they would take the next steps which would require them to keep the vehicle for a half a day and would involve doing more extensive work.

    My wife is nervous that she will run out of gas. Without filling up we have no way of knowing how much gas is in the tank, and if I understand the way the bladder works this won't even tell us.

    Is there something wrong with our gauge, or is this a normal phenomenon with the Prius? If it isn't normal, can it really be fixed? As a newbie, I'd appreciate any and all advice.

    Fritz:eek:
     
  13. Fritzenheimer

    Fritzenheimer New Member

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    P.S. The tech told me never to use Costco gas. He said he had seen several engines messed up with sludge from using Costco gas. Does this make any sense?
     
  14. qbee42

    qbee42 My other car is a boat

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    It's normal. You will know when you need gas because the gauge will read near empty. The maximum usable volume will vary from tank to tank, but the gauge will still be accurate at the bottom.

    Tom
     
  15. qbee42

    qbee42 My other car is a boat

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    No, that doesn't make any sense. Most gas comes from the same distributor for any given area. Some will vary the additives, but that isn't going to cause your car to junk up.

    Tom
     
  16. effwitt

    effwitt Paparazzi Magnet

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    Perhaps the local Costco station has a problem with their tanks.

    I'd hesitate to change my habits without verified facts to back it up. If a station is selling bad gas daily, they're going to be paying out claims that exceed their profits.
     
  17. jpadc

    jpadc Type before I think too often

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    Tom:

    Many of us here have run out of gas just as the gauge got to one bar. There is some variability in how predicable the empty indicator is on a given car, which I would say is "something" to figure out. I have had two Priuses (Prii?) now and their gauges were quite different in how reliably they indicated an out of gas state.
     
  18. john_dough

    john_dough New Member

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    It's normal for Prius. It's abnormal for almost all other cars. Also, some posters indicate gauge is not accurate around last two pips. Oh well, I suspect Toyota will redesign this in the future.
     
  19. archae86

    archae86 Member

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    Something real happened here in Albuquerque a few months ago, and it did affect Costco gasoline customers. But the problem had next to nothing to do with Costco and it could not have been reliably avoided by avoiding fueling there.

    What happened was that an error at the bulk station meant that diesel fuel was added to a gasoline bulk tank. Trucks delivered contaminated fuel to several stations around the city, and lots of cars operated very poory, needed to have their gas tanks cleaned out and in some cases their fuel injectors cleaned. As Costco had by far the largest number of customers per station, some of the publicity emphasized them.

    Not all the gasoline involved was probably identical, as a previous poster has mentioned the smaller volume additives are added after arrival at the the bulk station to customize the gasoline as required by brand. But I don't think anybody's additives would make up for any meaningful diesel fuel contamination.
     
  20. edthefox5

    edthefox5 Senior Member

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    Try this, let the gas tank vent a little. After my first gas tank belching episode I realized there was some trapped fumes in the tank compounded by the bladder design. But never any hissing gas release when you un-capped it. The fumes must be released as you fill and the bladder distends and releases pockets of trapped fumes. The Pius has a very strict fume recovery system. Too strict I think in order to meet its 0 Emissions mission. Now when I get gas I pull up to the pump. Open the gas fill cap. Do not insert the pump. Let it breath. Go inside and get a drink. By the time I come out the tank is vented & ready to go. Insert pump & fill on slow fill only ( I cut a tiny block of wood I jam under pump handle slow fill only) and no more early click off or erratic fill level. Hang the pump on first click off. I know I am defeating its fume recovery mission by letting it vent but whats worse dropping a gallon of gas on the ground instead?
    I knew for a fact it was not the pump clicking erratically. Not a pump problem because I always went to the same station same pump as my friend owns a station 1 mile from my house. It was always a different event at the same pump.
    This works every time now.:)