First time turning the key: Fuel pump won't prime/run

Discussion in 'Fox 5.0 Mustang Tech' started by 1990Coupe, Oct 19, 2008.


  1. sscobra

    sscobra New Member

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    Also, incase I missed it. Are you sure you have the right 02 harness? They are different between the years. It might do the fuel pump issue but it makes the car run like crap.
  2. 1990Coupe

    1990Coupe Founding Member

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    On the driver side shock tower i only have 1 plug and its brown.

    I think perhaps the horn could be an issue with someone telling me they gave me a 1991 harness when in all actuality i have different year headlight harness. I have not found any diagrams for the horn circuit.

    I am almost positive i have NO relay under the seat. tonight when i get home im pulling the seat out to check under the carpet. I did have the CCRM on the passenger side shock tower that was part of the 4cyl computer harness. It was discarded with the 4cyl computer harness and now i have a 1991 v8 computer harness. If there was no relay under the seat and it was on the computer harness wouldn't that mean i would need a computer harness from a 92-93 V8 inorder to have that fuel pump relay under the hood?
  3. 1990Coupe

    1990Coupe Founding Member

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    Yes im sure about this - the 02 harness plugged right into the 91 v8 harness
  4. 1990Coupe

    1990Coupe Founding Member

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    I honestly would have no idea where to even start to do something like this..

    i'm really bummed, i thought this was going to be plug and play like most all other 4-8 swaps i've seen.
  5. sscobra

    sscobra New Member

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    Not saying that you have the wrong one, but just because it plugged in to the harness in no way means it is the correct harness. Ford changed wiring pin locations between the years and used the same connector.
  6. hotcobra03

    hotcobra03 Active Member

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    Can u tell me what colors the wires are at the relay on the shock towers
  7. stykthyn

    stykthyn Commander of the snuggie cultists

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    91 IIRC was a stand alone year. there were changes made that year and that year only. 92-93 were different and using a 92-93 harness would only make things more difficult. there has to be something that we are missing here.

    is there a spare pig tail that you can put into the plug underneath the driver seat? put a bolt in it if you have to and turn the ignition to see if the FP primes.
  8. 1990Coupe

    1990Coupe Founding Member

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    I think i found the problem....

    [​IMG]

    This would explain the horn going off, and no relay under the seat. My car was built February of 1992. This would mean it falls under the ladder part of 92, meaning the relays were relocated, meaning i need a harness for a 92-93 meaning i'm a fking RETARD





    :(
  9. stykthyn

    stykthyn Commander of the snuggie cultists

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    sunnuva ****


    see if you can sell that harness for a 92-93 harness.
  10. josh072692

    josh072692 New Member

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    You may still want to check under the seat because that's where most fuel pump relays were on 92's is what I've heard because I am looking to do the conversion and have done a ton of research. Only the later 92's had the relay on the shock tower by the other. The wiring might be under the seat and the 4 cylinder might just not use it, so the relay isn't there but the wiring could be. It would just suck to pull out the whole harness to then find out that the wiring is under the seat.
  11. hotcobra03

    hotcobra03 Active Member

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    Can u tell me what colors the wires are at the relay on the shock towers.my pic shows a ac cutoff relay 11433
  12. stykthyn

    stykthyn Commander of the snuggie cultists

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    nah, if he's running a 91 harness I am amazed he even got it to start at all.

    90, if you cant find a harness send me a pm. I gotz one I was saving for a project.
  13. hotcobra03

    hotcobra03 Active Member

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    My diagram shows 2 plugs underseat.fp relay and power lumbar .relay is green and it shows 2 wires grounded to floor
  14. josh072692

    josh072692 New Member

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    Cobra what year wiring diagram are you looking at?
  15. 1990Coupe

    1990Coupe Founding Member

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    Nope - I pulled out the driver seat, took the sill off, pulled up the carpet and there is 100% no relay, harness, or plug under that seat. That is when i checked the door tag and went "oh s^&$" :)
  16. 1990Coupe

    1990Coupe Founding Member

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    I'll look at them in the AM and let you know :nice:

    I think i may be able to get one, im going to make a few calls tomorrow morning and i'll let you know. Thanks man! :nice:

    All i had under the seat was the plug for the power lumbar - there was also a ground bolted to the floor. I was the first one to take that seat out i can tell! :rlaugh:
  17. josh072692

    josh072692 New Member

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    Wow that sucks and you already updated your little profile thing at the bottom to say 92.
  18. 1990Coupe

    1990Coupe Founding Member

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    Haha yea.. I was really bummed. (you can click the progress thread to see where i began)

    I am so ready to start and drive the car, now i have to pull out all the wires and kinda start over there,

    Thanks to EVERYONE for all your help!! :nice::nice:
  19. hotcobra03

    hotcobra03 Active Member

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    My diagram shows 2 plugs underseat.fp relay and power lumbar .relay is green and it shows 2 wires grounded to floor
  20. hotcobra03

    hotcobra03 Active Member

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    Mine might be 2 early its .1988 ford shop manual,vol D powertrain group 24

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