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Fuel pump intermittently running while vehicle is turned off

Discussion in '1st Gen Tundras (2000-2006)' started by mnadventure, May 17, 2020.

  1. May 17, 2020 at 8:04 PM
    #1
    mnadventure

    mnadventure [OP] New Member

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    Hopefully some one can shine some light on my little issue here.

    2003 Tundra, 189,800 miles. I walked out of the house and heard something (fuel pump) running, I’d never heard this before and I’m usually in tune with odd/bizarre/irregular noises when it’s comes to vehicles & appliances.Had to run some errands, it started right up as usual, put it in gear pulled ahead 5 ft and it dies. Go to start again... starts for a second and dies again. 3rd.... attempt cranks with no ignition. After waiting 2-3 min I attempted to start again, it started rough and then died. I gave it a couple minutes again put the pedal on the floor and started it. As long as it was running at 3k-4K rpms it would continue to run, let off the gas and it dies. After multiple attempts to start it does and starts running fine all of a sudden. Take it out for a drive continues to run like normal.

    The only thing that is new, is that when you shut the vehicle off and pull the keys, after 25-30 seconds the fuel pump comes on and continues to run for 25 minutes or more (after 25 min I disconnected the battery)

    The fuel pump also doesn’t energize just before you go to start the vehicle and I can’t say I remember hearing it in the past (apparently not in tune with this fuel pump noise, the truck always starts!)

    Thinking this is a bad fuel pump relay? It was warm when I pulled it...

    any thoughts or experience with this issue?
     
  2. May 18, 2020 at 12:25 AM
    #2
    Ricardowelch

    Ricardowelch New Member

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    I read somewhere that "you need to check the fuel pump relay & make sure it's not stuck closed. If your relay turns out to be good, check to see if the relay's power circuit is energized with the car off. If so, the problem is either a short in the relay control circuit, or a bad ECU. If the relay's power circuit is not energized, then you're just going to have to start following the wire back from the pump to the relay, checking every so often to find out where power is shorting into the circuit."
     
  3. May 18, 2020 at 2:48 AM
    #3
    koditten

    koditten New Member

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    Can you switch the relay with another. I know on a 2nd gen the fuel pump relay and the trailer lighting relay are the same and can be switched.
     
  4. May 18, 2020 at 4:11 AM
    #4
    mnadventure

    mnadventure [OP] New Member

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    Koditten - the fuel pump relay is different than the other relays, nothing else to swap it with. I have another 03 tundra with the V6 and that doesn’t even use the same relay. Thanks for the response/recommendation
     
  5. May 18, 2020 at 4:14 AM
    #5
    mnadventure

    mnadventure [OP] New Member

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    Ricardowelch - I’ll check the relay circuit and relay tonight hopefully just a bad relay
     
  6. May 25, 2020 at 10:53 PM
    #6
    Tundra2

    Tundra2 Zoinked

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