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Thread: truck runs for 30 sec then dies help!!!!!!

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  1. #1
    Fuel Injected!
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    truck runs for 30 sec then dies help!!!!!!

    truck runs for 30 sec then dies. i have the 7747 pcm.tried oil pressure switch didnt work. but i dont have a hot fuel mod. injectors spray on start up then just stop. check all my grounds and double checked wiring. could the hot fuel mod be causing this problem? i am also running my stock 2.5l fuel pump relay that has gray for the fuel pump test that is ran to b2 fuel pump in put
    Last edited by lilhupper; 03-01-2013 at 09:42 AM.

  2. #2
    RIP EagleMark's Avatar
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    It's not the oil pressure switch, it is redundant and you don't even need it.

    But if oil pressure switch is bad it will not continue to provide power to fuel pump relay if fuel pump relay fails. Check the relay and see if the power to fuel pump stops at same time?

    There's a green wire to the relay that comes from the ECM that turns it on. But power comes from elsewhere, goes through relay when turned on by green wire from ECM and sends power to fuel pump.

    Relay is on firewall and looks like picture below, wiring is simalar but differant relay.

    HTH!
    Attached Images Attached Images

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  3. #3
    Fuel Injected!
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    yes the green wire goes out before the it dies

  4. #4
    RIP EagleMark's Avatar
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    If you hook 12 volt power up to the test/prime terminal and it runs? Then it would have to be the ECM? If wiring is correct. Is it consistent 30 seconds each time? Will it start after the stall?

    Here's a link to diagram.
    http://www.gearhead-efi.com/Fuel-Inj...8&d=1331599730

    Do you have one of these on your harness?
    Attached Images Attached Images

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
    -= =-

  5. #5
    Fuel Injected!
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    yes its a consistant 30 sec and will fire after stall. no i dont have that.

  6. #6
    Fuel Injected!
    Join Date
    Feb 2013
    Age
    32
    Posts
    101
    puting a constant power to the test wire doesnt help motor still runs for 30 sec then dies. does anyone know what the fuel mod does. im going to go over the wire harness to night and make sure all wires and hooked up correctly and none of them are pinched.

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