Ford5literStang

I have a 90 mustang 4 banger and i put a 89 5.0 in it. I have the computer and the harness hooked up in the car. I swaped the other harnessin the engine compartment, but i left all the inside wiring the same. The steering wheel also got swaped to a 89 tilt wheel. So after all that when i turn the key to the on position the fuel pump doesn't prime like it should. Its not the fuel pump or the relay cuz the fuel pump turns on when i jump it at the relay. If no one can help me ill just sell the car $1800 or best. I have lots of other mustang parts just ask to see what i got.

vlouis96gt

do you have a electrical diagram for your harness? Because on my 95 bronco 5.0 the pcm relay controls the voltage to the fuel relay. It gives you 6.7 volts in on state, and will give you close to 12v on start cycle. You may need to add this fuse block and wire it according to drawings or you could maybe cut supply volt wire before relay and direct wire to a start/on ignition wire. good luck, bronco had bad fuel pump