1983silverbullet

Hello, i have a 1983 mustang with a 5.0L swap. i was driving last night for about 2 hours and did not notice anything strange. i shut the motor off and when i went to start it up in the morning it would not start. there is spark and it cranks over but the fuel pump is not turning on. i have replaced the pump and made sure the switch located in the back of the trunk is ok. what do i do from here? i have tryed finding a fuse in the fuse block but one doesnt exist. please help!

1983silverbullet

Update: i checked for power at the relay and there is power to the orange and light blue. aswell as the red wire. but not the tan/light green and pink/black

MustangBradley

Pull the plug at the pump. Test for power there when the key is first turned on. You will need a friend to operate the key while you are testing the plug.

What year is your 5.0? EFI or carb? describe your fuel system.

TrimDrip

If you loop the orange and blue wire with the pink and black wire. The fuel pump should cut on. If it does, get a new relay. If it doesn't you have problems elsewhere.

It will also work looping the red wire with the pink and black wire.

1983silverbullet

ok i will have to try that first. i dont get power at the tan and green wire at the relay but at the test port in the engine bay near the wiper motor i get 1.60v with power on. what is this wire? its a 5.0 efi thanks

TrimDrip

V This is what you need. Loop the orange wire with the pink and see if it cuts on. My guess is, the circuit isn't closing when the red energizes the tan/green if the fuel pump cuts on when you loop it.

1983silverbullet

update. i jumped the orange wire to the pink and it kicked on so i went otu and bought a relay again. didnt work. so i backprobed the tan and light green wire at the relay and just grounded it. vola! it turns on. all of a sudden i took the jumper off and the car worked like a charm like it fixed itself. ran great for an hour and started like 6 times. all of a sudden it died and wouldnt start until i jumped the tan wire to ground again. does this mean the wire is corroded somewhere? and doesnt go all the way to the comp to complete the circuit or what? i need help.!!!!

TrimDrip

yeah, it is a bad ground on the tan wire. It should be at .5 volts or less instead of 1.6. Sorry for misguiding you a bit on that.