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Fuel Bladder Capacity and the Weather

Discussion in 'Gen 2 Prius Main Forum' started by srellim234, Jun 6, 2016.

  1. srellim234

    srellim234 Senior Member

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    Experienced owners already know this but I figured I'd throw out some figures on how much variance some people can see when they are new to dealing with a Generation 2 Prius.

    After colder, wet weather (at least cold for us) our 4/30/2016 fillup at one bar left on the gas gauge was only 6.235 gallons. The fill before that was 2 bars and 7.533 gallons. Today, after a week of 90-102F* weather a fillup with 3 bars left was 8.014 gallons. Note that even though the gauge indicated a lower amount of fuel left on 4/30 we were able to put more in the tank on the other fills.

    This is just a hard copy demonstration of the variance one can experience when filling the fuel bladder. Gas mileage over many fills will be a decent indicator of fuel mileage but tank capacity can vary dramatically and throw any one-tank calculation off. One tank is not necessarily indicative of something drastically wrong with the car.

    Just another reason why we try to fill around two bars every time. We're never sure how much fuel is really in there.
     
  2. dorunron

    dorunron Senior Member

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    As a former Gen II owner, I can say very truthfully that your information is spot on. Practice P&G when you can and during the summer if you are lucky and the stars are aligned properly you should be able to get 50 or better out of it for a average over several tanks.

    Best of luck to you. (y)
     
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  3. wjtracy

    wjtracy Senior Member

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    We also experienced 6 gal winter fill-ups from one pip a few months ago. My theory is it may have something to do with winter gasoline, which has higher vapor pressure, may cause the system to click off sooner.

    Only as of June 1 is summer gasoline mandated everywhere, so I am hoping we get better fill-ups soon.

    But I feel a little differently about the 2-pip fill-up strategy. In warm weather we can fill up to 12 or 14 pips. I know there are really only 10 pips, but that 10th pip is about 3-gals on a real good fill-up. What's happening in winter is we are only getting 0.5 gal at most in there for the last pip. So the last two pips is still the last two pips - about the same volume (of course MPG is worse so it goes faster in winter).
     
  4. srellim234

    srellim234 Senior Member

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    Thanks, dorunrun. I really don't have much opportunity to P&G since I usually have an impatient wife and two teenage daughters in the car with me. I do ease up on the gas pedal when I can and try to avoid using the cruise control on rolling highways. I expect mileage is going to go up over the summer just based on a bunch of steady highway driving and very little short hops here in town. After spoiling myself this last school year by driving to my local job I'm setting up my bicycle for a return to riding it around town more. Better for the wallet while being better for me physically and emotionally.
     
  5. dorunron

    dorunron Senior Member

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    Even if all you do is keep your tires pumped up to max and run "synthetic" oil unless you have really poor NON LRR tires you should see better mileage in the summer especially if you limit your short trips. Anything over 62 MPH on the highway will cause the MPG to drop, so take that into consideration. When you think about it though, 40 MPG is decent in today's terms anyway.

    Best of luck to you. (y)
     
  6. srellim234

    srellim234 Senior Member

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    wjtracy - You're correct. The difference is that we are not concerned about stretching it. Whether we fill up at this town or the next makes little difference to us most of the time on a long trip. We don't use the Prius as a commuter car so whether we fill it every nine days or ten days doesn't really matter either. So, we just play it safe.

    I would definitely pay more attention to it if I had to fill it up every 2-5 days. As it is we if we're out and about and don't have anything pressing going on we'll take the time after we hit two pips. We usually are looking at two pips for 3 days anyway when we're in town so we just stop if it's top tier gas at a reasonable price and it's convenient. We don't make special trips for it.

    We also like being prepared in case of emergency. Keeping the cars fueled up covers us in case of earthquake (we are near the San Andreas fault) while our son and one of my wife's sisters live 120 miles away. Nice to always have at least that much in the tank.
     
  7. tony2ltr

    tony2ltr Member

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    I found that if you pump the fuel in very slow, You can get just over 11 gallons every time.

     
  8. seeker311

    seeker311 Junior Member

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    Do you know why that is? We have an 06 with 203k miles and we were told the bladder may be going out, but if the approach is just to pump slow, then the guy behind me is going to wait while I get the 11 gallons. Thanks.
     
    #8 seeker311, Apr 16, 2018
    Last edited by a moderator: Apr 16, 2018
  9. DMC-5180

    DMC-5180 Active Member

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    First of all, if your trying too get 11 gallons in the tank. You are driving on fumes to do it. I have run out of gas once in my Prius, fortunately I was only a 1/4 mile from the gas station I was headed too for fuel in the first place. I was able to limp in with slow speed EV mode. Got the Red triangle too. I had too clear the codes with the code reader I was fortunate enough to have in my glovebox. The car would not start until I cleared them.

    After I filled up I was able too Verify the Max Capacity as stated in the owners manual IS achievable and accurate,IF you nurse the last gallon to the point that the fuel is sitting at the filler neck opening. I find that typically if you fill with the nozzle fully inserted and set too the slowest trigger lock position, it will click off with about a full gallon to go. I pull the nozzle out to the point where I can see the gas flowing and nurse the nozzle until the gas is settled and visible at the opening. This last gallon or so only takes about a minute at the most. If you try nursing the fuel with the nozzle inserted you will be there for a while as you are fighting the auto trigger shutoff. And if you force fuel it you WILL get the fuel bladder push back BURP. This is why you have to fill the last gallon will the nozzle resting on the Cap flange.

    Btw, I only top off like this when I know I will be burning it off with continued driving. I never top off and park it like that.

    generally, I normally don’t wait for the low fuel warning before refilling. My typical top off refills are 7–9 gallons. That’s typically around 2-3 fuel bars showing. If I Do wait for the Low fuel beep warning, it will be in the 11 gallon neighborhood.


    iPhone X ?
     
  10. wjtracy

    wjtracy Senior Member

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    I personally do not see much benefit of slow filling, although I try not to fill too fast.
    Our 2006 is only taking maybe 7-gals from empty (on a good day), and all I can assume is the bladder is bent so it does not fill out. Usually better in summer. We never saw much more than 9-gals fill up from blinking pip. There is probably a couple gallons reserve, so anyone getting 11-gals in a USA Gen2 is really going dry past the blinking PiP. Although there could be differences between vehicles.