Engine noisy when tank is low(!?!!?!)

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Ianmeister, Jun 7, 2019.

  1. Ianmeister

    Ianmeister Active Member

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    hey all. So I’ve seen some fuel filter/fuel pump threads and the consensus for North America cars is “no user serviceable parts inside”. Hmm ok. So anyway I’ve noticed that when my ‘06 with 217k miles, recently purchased, becomes lower in fuel the gas engine gets louder and louder. Not lawnmower loud but it is worrisome. Today I noticed that as soon as I fill the tank up it becomes nearly silent. It’s not a subtle difference it’s night and day. Keep in mind the change starts at the first start up while it’s still burning fuel from the previous fill up. Strictly tier 1 87 octane chevron gas. Same station, same pump. It’s like something about the extra pressure from a full tank makes the engine run like showroom fresh? Any ideas?
     
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  2. Skibob

    Skibob Senior Member

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    You could try checking the fuel pressure with a full and near empty tank and see if there is a difference. That would be my first step. And yes if your pump is shot or fuel filter inside the tank is clogged you need to buy a new fuel tank. 77001-47090. Tracy Toyota internet price is currently 452.41 new. Or you could get a used one.
     
    #2 Skibob, Jun 7, 2019
    Last edited: Jun 7, 2019
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  3. sam spade 2

    sam spade 2 Senior Member

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    How LOW do you let it GO ??

    The extra noise could be coming from a failing fuel pump......which you don't hear as long as it is immersed in fuel.
     
  4. Ianmeister

    Ianmeister Active Member

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    To the first ping of low fuel then 2 minutes to the closest station. It took exactly 9 gallons.

    I’ll try the pressure thing.
     
  5. Skibob

    Skibob Senior Member

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    Do you mean the first dot? 1 dot lit? That’s pretty low, Prius gas gages are not known for their high accuracy. 9 gallons is a lot but I can’t say if you were about out of gas or not. You were pretty close though. Does it make the sound when you have 2 dots of fuel left?
     
  6. Ianmeister

    Ianmeister Active Member

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    Yes. Even 3
     
  7. Ianmeister

    Ianmeister Active Member

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    I think I’ll just refill at 2 dots need it or not
     
  8. Skibob

    Skibob Senior Member

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    Fuel pressure check then.
     
  9. Ianmeister

    Ianmeister Active Member

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    Where’s the Schroeder?
     
  10. Skibob

    Skibob Senior Member

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    I don’t think there is a schrader valve to check the fuel pressure. You have to tap in. I’m sure someone here will post the procedure.

    @SFO
     
  11. edthefox5

    edthefox5 Senior Member

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    I doubt its got anything to do with fuel level whats probably happening is the hybrid battery may be tdying and when that happens only thing left to power the car is the tiny little under powered engine. The engine will be screaming to go anywhere. I suspect the hybrid battery is bad because that's like the #1 reason people dump there used G2.

    Next time it starts doing it monitor the battery level on the mfd. I bet the battery is in purple which is basically empty.

    Or just watch the battery level....if it goes from blue to purple real fast and will not go back into blue within 2 miles its time for a new battery or a rebuild.
     
  12. Skibob

    Skibob Senior Member

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    Why would you think it’s the battery when the fuel gets lower? If anything it would be opposite. The car gets lighter as the gas tank empty’s
     
  13. Ianmeister

    Ianmeister Active Member

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    Agree with Skibob. Today for example the car was one battery bar short of 100% green, fuel gauge was blinking one spot when I pulled into the gas station. Filled up. On restart I wasn’t sure if the ice was running it was so quiet. For reference the only times I got the battery down to purple on a looooong high speed uphill run it bounced back to light blue in under 5 minutes. I really don’t think it’s Hybrid battery related.
     
  14. Skibob

    Skibob Senior Member

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    You really need to check your fuel pressure. I guess best way would be to check it at home when the gas tank was almost empty, then throw like 2 five gallon gas cans in and see what the pressure reading is then. Plus I was not kidding about the gas gage. Plenty of posters here have run out of gas on 2 dots. The gas gage on a gen 2 prius is more of guess than anything else. It’s the stupid fuel cell. Even NASCAR has troubles with it. And they get millions to work it out.
     
    #14 Skibob, Jun 8, 2019
    Last edited: Jun 8, 2019
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  15. Ianmeister

    Ianmeister Active Member

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    Ok. 3 dots fill up from now on :)
     
  16. frodoz737

    frodoz737 Top Wrench

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    If you ran diesel, I'd say you were sucking water from the bottom of the tank.
     
  17. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Is the gas station at the top of a hill? I mean I don't think it's that simple, but technically that would explain things.
     
  18. sam spade 2

    sam spade 2 Senior Member

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    Regardless of the noise you are trying to identify......THIS is a BAD habit and you need to work on changing it.
    Someday it will bite you in the butt and the engine will go completely quiet......when it runs out of gas. :eek:
     
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  19. Ianmeister

    Ianmeister Active Member

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    No it was on level ground
     
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