Fuel Fuel Pump Not Working.

Discussion in 'Fox 5.0 Mustang Tech' started by JPD686, Aug 10, 2012.


  1. CobraWannabe

    CobraWannabe Member

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    Assuming your next question is if I have power at the black/pink wire going to the fuel pump relay; I just can't seem to find a pink/black wire. I found 5 fuse links coming from the starter solenoid. All are good. Besides, I do have power at the green/yellow wire coming from the fuel pump relay (with the key in the "run" position), so my next check should be at the inertia switch, right? And that's where there seems to be a problem, because there's no green/yellow wire going to the inertia switch. And no brown/pink wire either. There's only 2 red wires. Neither side has power.
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  2. CobraWannabe

    CobraWannabe Member

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    And now for the fun part. Mixed harnesses. From the dash back to the back of the car, I'm pretty sure is wiring for a 1990 (which is the year of this car). The rest (engine/computer) is from a 93 Cobra. That explains the red wires at the inerta switch. And I also have a relay under the drivers seat. I assumed my brother used the entire harness(es) from the donor car. Waiting to hear from him. BUT.....this car was running for a while the way it is. I'm going to have to study both wiring diagrams for a while to figure this one out. Hopefully he just has the rest of the harness.
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  3. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    That sheds an entirely new light on things: the fuel pump circuits are wired differently. The 90 car has the inertia switch inline with the control for the fuel pump relay coil. The 93 has the inertia switch inline with the power feed for the fuel pump. You have both diagrams and descriptions in this post, so that's a start. I'll need some time to think about what and where to look for problems.
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