Fuel pump running continuously after being parked for several hours

Discussion in 'Gen 3 Prius Technical Discussion' started by Glen England, May 24, 2025 at 10:48 PM.

  1. Glen England

    Glen England Junior Member

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    I've got a 2015 Prius with just over 100,000 miles on the clock.

    It has never had anything major worked on since I've had it around 55k.

    The last time I drove it today was about 7 hours ago.

    I needed something from the garage and noticed that the fuel pump was running. I spent 15 or 20 minutes in the garage working on something and the pump ran the entire time I was in the garage without ever stopping.

    I'm not having any drivability problems or fuel economy issues that I've noticed.

    Maybe the relay needs to be replaced?

    The only other thing I've got starting to happen is the dreaded brake booster issue. The pump runs every 15 seconds or so if I'm sitting still with the car on.

    Thanks in advance for any tips.
     
  2. Tombukt2

    Tombukt2 Senior Member

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    And you're hearing this fuel pump where I guess the car must be in a closed garage and you're sitting at a workbench doing something I mean the fuel pump is in the gas tank not quite in the middle of the car more to the rear of the car I can't really hear mine running and my old lady says I don't miss anything in the hearing department except when I don't want to hear something so I can't imagine you are hearing this fuel pump running that's that's got me going pretty good because I can't hear any of mine running even when I want to hear them car on ready gas stepped on engine running my ear at the filler neck with the door open and the cap off and or my head under the car and my ear against the fuel tank and even then barely can hear the denso electric fuel pump barely hearing at 5 ft from the car almost out of the question 10 ft not at all so that's pretty good we are talking the fuel pump in the tank or are we talking The crickets under the hood or some other nomenclature that I don't know about because fuel pumps on Toyota or anything but noisy generally speaking.
     
  3. ASRDogman

    ASRDogman Senior Member

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    HOW do you KNOW it was the fuel pump, and not the brake booster?
    WHY did you just let it run??? (n)(n)
    Did you not think to check it out and find out what was running? Then stop it?
    Maybe a door was not closed all the way? Maybe a stuck relay????

     
  4. Grit

    Grit Senior Member

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    Evap test after 4 hours of driving. Fuel pump can only be heard with back bench removed.
     
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  5. Mendel Leisk

    Mendel Leisk Senior Member

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    That just runs for a few seconds though.
     
  6. ChapmanF

    ChapmanF Senior Member

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    The leak detection pump runs all through stages B, C, D, and E of the test, so it looks like seven minutes and ten seconds plus however long part C runs. Part C could take up to 15 minutes, so it seems like the longest time you could hear the pump run would be twenty-two minutes and ten seconds worst case.

    [​IMG]

    The test starts after about 5 hours of not driving—so, typically overnight. The delay can be more than 5 hours if the temperatures aren't suitable.
     
  7. Tombukt2

    Tombukt2 Senior Member

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    That's my generation to run the same nonsense? I have never noticed anything running and I'm up all kinds of odd hours of the night out on my property right next to the cars I've heard the coolant heats tank storage pump come on after the 5 hours I guess I wouldn't know if the fuel pump was running I've never heard that I can't hear the fuel pump on my generation too not even at 4:00 in the morning when everything is quiet as all get out outside and I even go out and turn the car on even putting my ear to the filler neck or getting under the car and putting my ear on the fuel tank itself yeah the thing with the rust coating on it the tank I can barely hear it then and I mean barely and my hearing is pretty good so hearing that 5 ft across at the carport even at 4:00 in the morning when it's quiet is probably not going to be a thing I think this is pretty good pretty rich whatever you want to call it I can't imagine I have done so fuel pump sitting here on my bench that I can put 12 volts to in my hand and can barely hear them but I can feel them I don't think we're hearing a fuel pump running personally but