Gas tank\gauge issues?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Marci D., Apr 28, 2025 at 12:46 PM.

  1. Marci D.

    Marci D. Junior Member

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    I have a 2008 Prius. Recently went to the gas station with 3\4 tank and filled up. It took over 5 gallons at which point it overflowed without shutting off. I've noticed that in the week since filling (overfilling) my gas gauge remains at full. What broke? Can I fix it so it registers again?
     
  2. MAX2

    MAX2 Senior Member

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    How far did the car travel in a week?
     
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  3. bisco

    bisco cookie crumbler

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    there is a rubber bladder inside the gas tank. much like myself, itbecomes less flexible with age, and doesn't work properly. that can lead to inaccurate tank level readings.
    overfilling can foul the charcoal canister part of the environmental system. is it running okay with no trouble lights?
     
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  4. Mendel Leisk

    Mendel Leisk Senior Member

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    It's not unusual for the gas gauge to remain at full till for 50~100 miles, especially if it was really full. The only problem "may" be a malfunctioning auto-shut-off mechanism on the gas station pump.
     
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  5. Marci D.

    Marci D. Junior Member

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    The car is otherwise running okay. The only other issue it has (for the last 6 weeks) is the indicator light for low tire pressure is on although all tires and the spare are at the correct level.
    I can't be certain how far it has traveled. If I reset the trip meter at fueling it is 260 miles but it might be as little as 150. I can't be sure how many times I took this one out this week.
     
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  6. pasadena_commut

    pasadena_commut Senior Member

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    If all the tire pressures are correct the TPMS light is probably just a dead battery in one of those units. Caveat, if the tires were rotated front to back and then the pressures adjusted a (former) high pressure tire might trigger the warning if it is low. Probably not though, I don't remember the exact number, but the cutoff set on a 32 PSI tire was something like 26 PSI and the 35 PSI one was just a smidge more. That is, it is a pressure much lower than what most people would intentionally use.

    The gas gauge isn't linear. As Mendel Leisk said, there is no change in the reading until something like 2 gallons have been used.
     
  7. MAX2

    MAX2 Senior Member

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    Usually after a full tank the distance traveled indicator on the MFD is reset and a new report starts. Fuel consumption in miles is saved unless you press reset.

    The fuel gauge in the tank on the American version of the Gen2 is designed unevenly so that the first decrease of the ten indicators of tank fullness goes away after a decent distance. On the weekend I filled up my Gen2 to the brim and drove about 320 km (200 miles). Only after that one indicator out of ten went out. Then I drove about 50 km (30 miles) and another indicator went out.
     
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