Can't get '89 5.0 to prime

Discussion in 'Other Auto Tech' started by 89 Fox 5.0, Jan 12, 2012.


  1. 89 Fox 5.0

    89 Fox 5.0 New Member

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    Hello, i am new to the site.

    I have a 1988 mustang with an '89 motor and wiring harness. I Picked up the car in Sept. At one point the alternator was no longer charging and I had to replace both alternator and battery. Now the fuel pump no longer primes when turing the ignition. I had a mechanic buddy of mine look at the car to test the voltage, relays, and the inertia switch of which all seem to be okay. I am at a loss at this point.

    Any suggestions​
  2. arco777

    arco777 Member

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    Was the car originally a 4 cylinder or 8 cylinder? If so there are various pin differences in the harnesses and if something was jury-rigged to work it may have let go. I worked on converting a 4 cylinder car to a V8 recently and the two immediate issues I ran into trying to use some of the I4 harness were no ignition signal and no fuel pump signal.

    That said, the fuel pump wiring is pretty simple and you can always run a new trigger or even full pump wiring yourself.

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