Fuel pump Wiring color codes on 89 GMC 1500

Discussion in 'GMC Truck Forum' started by granbro, Feb 5, 2009.

  1. granbro

    granbro New Member

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    Hello: I'm wondering if anyone has any idea what the color codes would be on the fuel pump wiring on my 89 GMC.. I have a Haynes manual, and the hot lead to the pump is listed as gray, coming from the pump relay to the pump. However, I have no gray wires at that point. Also, according to Haynes, the fuel pump prime connector is supposed to be red... can't find a red wire there. Any help would be appreciated.
    Thanks
    granbro
     
  2. silverhairdeere

    silverhairdeere Senior Member

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    #2 silverhairdeere, Feb 5, 2009
    Last edited: Feb 5, 2009
    according to chiltons the wires that go to the fuel pump in the tank are tan/white and pink the wires that go to the fuel pump relay are green/wite , black/wite ,red,orange, gray


    shd

    [​IMG]
     
  3. crabtruck

    crabtruck Senior Member

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    Welcome to the forum granbro. What are you trying to fix ?

    Far as I can tell the 88-90 R/V and the 88-98 C/K's are wired identical.
    The red wire is for "priming" as part of a shop proceedure, not normal driving.
    As in, if it were missing, it wouldn't actually be missed. It does give you a place
    at the dashboard to see what the fuel relay is doing and to bypass it for testing.
    It is found at a connector known as the ALDL or DLC on terminal "G".

    The hot from the relay is grey, but becomes tan/wht at the splice
    at the oil pressure sw. That should be power to pump.
    Simple tan should be the sender at the tank, but may be pink.

    You have to take all these drawings with a grain of salt.
    For example in the one I show, the "ECM B FUSE"
    may actually be a fusible link to battery.
    You may or may not have the "Fuel Module" on your truck.

    Let us know what the problem is and we can do better.
    If it's "pump not working" you may want to check plug on oil press sw is tight
    and the pump fuse near relay is good as a starting point.
     

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