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Thread: Trick the fuel pump to drain the tank?

  1. #1
    Senior Member Dave 53's Avatar
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    Trick the fuel pump to drain the tank?

    The gas in my tank is from the previous owner and is probably about 2 years old now. Quick Google search said gas is fresh for about 6 month. The engine started right up and seemed to run fine when I last started it 4 months ago, but I'd like to drain the fuel system and start over with fresh gas before I start the engine again. Is there a way to trick the fuel pump into running so I can pump the old gas into a jug?

  2. #2
    Papa's Avatar
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    It's simple to power the pump directly from a battery. Just disconnect the +/- wires and alligator clip from a battery to the pump. You'll need to plumb a fuel line from the tank to your jug. of course.
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  3. #3
    Senior Member Dave 53's Avatar
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    Hoping for an easy trick, like maybe disconnect the starter motor (easy, accessible, one bolt), then try and "start" the car. (would that work?)

  4. #4
    Senior Member Bob_n_Cincy's Avatar
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    Quote Originally Posted by Dave 53 View Post
    Hoping for an easy trick, like maybe disconnect the starter motor (easy, accessible, one bolt), then try and "start" the car. (would that work?)
    The pump will only run for a few seconds. The ECU would sense the engine not spinning and shut off the pump.
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  5. #5
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    Depending on how you have it plumbed, you might be able to easily unplug the return line from the tank and put it in a jug.

  6. #6
    i.e.427's Avatar
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    Pull the fuel pump relay and jumper across terminal 30 and 87. Turn the key on and it will pump until you turn off the key.

  7. #7
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    I'm jumping on this post because I'm trying to diagnose bad fuel pump, relay, or bad wiring so I'd like to jump the relay.
    Do you know the wire colors of 30 and 87? I'm struggling to read the diagrams, if I even have the right one.
    Or is there a way I could give 12v to 2 of the 6 terminals of the pump?
    Donor is 06 wrx

  8. #8
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    Quote Originally Posted by Dutch602 View Post
    Donor is 06 wrx
    Turbo or N/A?

    The directions above to jump 30 and 87 refer to generic terminals on a relay. For instance on a 2006 Turbo you would want to jump pin 2 (30 on the relay, wire is blue with red stripe) to pin 4 (87 on the relay, wire is black with yellow strip)

    Simple 5 Pin Relay Wiring Diagram.jpg
    Last edited by Ajzride; 02-22-2021 at 08:50 PM.

  9. #9
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    Thanks for the diagram, I'm turbo

    FP Relay.PNG

    Is this my relay?

    If so there's 6 wires going to it. I'm probably way off!

    PXL_20210223_005954063.jpg PXL_20210223_010006821.jpg

  10. #10
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    That is your fuel pump control module. The black wire with yellow stripe should lead to the relay.

  11. #11
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    Thank you! I traced the wire back to a green connector and realized I didn't have the relay plugged in. I thought the controller was the relay.

    In case anyone else needs it, the round part with the green connector in the picture here FP Relay.PNG is the fuel pump relay.

  12. #12
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    I think the other relay is your DBW power, make sure it stays plugged in too.

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