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Thread: Fuel pump not priming. Now what?

  1. #21
    Guy with a DeLorean Mark D's Avatar
    Join Date:  May 2011

    Location:  Stevens Point,WI

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    Since you don't have either end of the fuel pump harness still intact you have a few more options rather than trying to source both ends of the original type connector..

    As you mentioned, the short harness from the pump is readily available but it's probably going to be tough to find the mating connector from the front chassis harness. The conector itself is not available separately so unless you can harvest one from a scrap harness and splice it in you probably won't have much luck.

    Unless you're really looking to maintain originality the easier and cheaper option would be to just use a different off the shelf connector. Your local auto parts store should have connectors that you can use to make your own short harness from the pump with corresponding connector on the harness.

    A simple 2 pin weathertight connector like this would work.
    http://www.autozone.com/autozone/acc...er=139516_0_0_

    If you decide to use a non standard set of connectors just be sure they're set up for the correct wire gauge.
    Last edited by Mark D; 06-06-2013 at 01:02 PM.

  2. #22
    Senior Member krs09's Avatar
    Join Date:  Jul 2012

    Location:  Philadelphia

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    My VIN:    4870

    [QUOTE=Mark D;106665]Since you don't have either end of the fuel pump harness still intact you have a few more options rather than trying to source both ends of the original type connector..

    As you mentioned, the short harness from the pump is readily available but it's probably going to be tough to find the mating connector from the front chassis harness. The conector itself is not available separately so unless you can harvest one from a scrap harness and splice it in you probably won't have much luck.

    Unless you're really looking to maintain originality the easier and cheaper option would be to just use a different off the shelf connector. Your local auto parts store should have connectors that you can use to make your own short harness from the pump with corresponding connector on the harness.

    A simple 2 pin weathertight connector like this would work.
    http://www.autozone.com/autozone/acc...er=139516_0_0_

    If you decide to use a non standard set of connectors just be sure they're set up for the correct wire gauge

    Beautiful. That will be perfect. Any idea of the correct gauge. 10-12?

  3. #23
    Guy with a DeLorean Mark D's Avatar
    Join Date:  May 2011

    Location:  Stevens Point,WI

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    My VIN:    6125

    I'm not sure what gauge the wire is. Does anyone else know? I thought it was listed on the wiring schematic but it does not show wire sizes.

  4. #24
    EFI DeLorean dmc6960's Avatar
    Join Date:  May 2011

    Location:  Minnesota

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    Quote Originally Posted by Mark D View Post
    I'm not sure what gauge the wire is. Does anyone else know? I thought it was listed on the wiring schematic but it does not show wire sizes.
    Probably something I shouldn't say unless I'm 100% sure, to which I am only 90%. I believe it is 14ga, small chance its 12ga but I'm pretty confident on that 14.
    Jim Reeve
    DMC6960

  5. #25
    Senior Member Bitsyncmaster's Avatar
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    Location:  Leonardtown, MD

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    Quote Originally Posted by dmc6960 View Post
    Probably something I shouldn't say unless I'm 100% sure, to which I am only 90%. I believe it is 14ga, small chance its 12ga but I'm pretty confident on that 14.
    14 AWG will be fine. I think the stock wire is more like 15 or 16 AWG.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  6. #26
    Senior Member krs09's Avatar
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    Ok. I headed out to the store to pick up some 14g wires and some spade male and female connectors and got to work. After I had both of the wires connected and ready to go I turn the key to on (prime) and got nothin. So I broke out the mulit meter and found I do have 5 volts going to the pump with the key on and a jumper in the RPM relay and the pump seems dead, not a thing. When I take the jumper out and put in the relay I get no reading with the key on ( Normal? ). So now Im thinking the pump is shot but even with no reading from the mulit meter and having the key on I can fell the hoses coming out of the pump pulsating, like fluid is flowing thru but not a sound.. Weird... Im I right in thinking the pump is dead, If im getting 5volts going to the pump with a jumper in place but the pump completely silent? Is it normal to get no reading when using the RPM relay with the key to on? Thanks to all you guys for holding my hand on this

  7. #27
    Senior Member
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    Location:  Burnsville MN-Moving to Kalispell MT. in June 20111

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    fuel pump helps

    I've heard that you can switch the wires to the pump and force the pump backwards to unjamb debris. then hook it up right to run it forward. Do this back and forth and often you can clear the pump to run again. Correct me if i'm wrong because I have not tried it.

  8. #28
    EFI DeLorean dmc6960's Avatar
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    5 volts is not right! The pump needs 12v to run. Test the voltage with the pump disconnected. If you then get 12v you have bad wiring somewhere. Individually test the 12v and GND leads to the fuel pump with known-good 12v and GND sources.

    Get some spare wire and hot-wire 12v and GND directly to the pump. If it still doesn't work, THEN your pump is toast.
    Jim Reeve
    DMC6960

  9. #29
    Vin3299's Doc DeLorean03's Avatar
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    Quote Originally Posted by dmc6960 View Post
    5 volts is not right! The pump needs 12v to run. Test the voltage with the pump disconnected. If you then get 12v you have bad wiring somewhere. Individually test the 12v and GND leads to the fuel pump with known-good 12v and GND sources.

    Get some spare wire and hot-wire 12v and GND directly to the pump. If it still doesn't work, THEN your pump is toast.

    That is 100% correct.

    I would strongly recommend either retracing and repairing the wiring to the inertia switch, or you can run dedicated power and ground wires directly from the battery (+) and the frame (-) to the pump. I did option #2 with both my old Hervey's pump with baffle kit and currently with DMC's new fuel pump sender combo - obviously do at your own risk.
    DMCTalk.org Moderator

    Actual snippet of a conversation from Sept 2013:

    Me: Eddie, I can't wait to get the car back when you're done with it.

    Eddie: Yeah, you'll be able to give the car gas, and it won't be - like - embarrassing....

  10. #30
    Senior Member Bitsyncmaster's Avatar
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    You have a bad connection somewhere.

    Your pump should run down to 10 volts or so. At 5 volts you would get nothing.
    Dave M vin 03572
    http://dm-eng.weebly.com/

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