redmustang83596

Car is a MAF converted 1986 mustang 5.0L.

My fuel pump isnt turning on. I cant figure out why. It was working fine, then it stopped turning on. I must have pulled a wire out of somewhere or something when i was taking some of my interior out. But the problem is weird. When I jumper the fuel pump from the diagnostic port, the fuel pump turns on. When I pull the PCM out of the car, and I ground the pin for the fuel pump, the pump turns on. So putting two and two together, the circuit is fine and its just the ground thats not right. Since the PCM grounds the circuit, I figured the PCM may be bad, but I put the PCM in a different car and it works just fine. The EEC relay and the fuel pump relay were both tested and both are fine. There is power going to the PCM also. I am STUMPED and its really annoying the living hell out of me. Someone PLEASE help me with this **** before I set this hunk of **** on fire.[/align]

redmustang83596

bump, anyone???????????/

black89gt

check the relay yet?

Kick_Ass2k1

Well looks liek you know how the pcm makes the fuel pump turn on and tested out that route, but do you know what makes the ecm turn on the pump? I'm not sure if that may help (dunno if you already thought about that). I have no clue what does it, fuel pressure? Is there some signal that the ecm isnt getting so that it is not turning on the pump? Sorry cant be much more help, good luck, and let us know what you find!

mattdel

i'm bettin your eec ground is bad

redmustang83596

EECground is fine. there is an orange wire and a black wire that ground the PCM and both have around .5OHM resistance from the pin to ground, so there is continuity. I dont know what if there is a signal that turns the PCM on but whatever it is its not working, does anyone know what this is???

redmustang83596

anything???? anyone????

Joel5.0

Check the following pins at the ECm connector, ECM disconnected....

1. Resistance/continuity check at pins 20, 40, 60 to ground...should be less than 5 ohms.

2. Pin 1 for 12-vdc always hot.

3. Pins 37 and 57 for 12-vdc IGN ON

redmustang83596

Continuity from 20 to ground, OL from 40 to ground and from 60 to ground.
Very little voltage from 37 and 57 when IG is switched on.
PIN 1 is hot at all times.

How sure are you about those pins? In the manual it says 40 is for the oxygen sensor, and that 60 is the ground side for the EEC Main Power Relay. It also says pin 37 and 57 should have voltage when the EEC Main Power Relay is switched open, so the EEC relay is NOT switching open, just like the fuel pump relay. So how sure are you about the ground pins? It says pins 20 and 49 in the book. Im confused?

redmustang83596

Well I just checked Ford Fuel Injection.com and its the same grounds for every year harness, MAF or not. So idk what the hell the chiltons manual is talking about. Thanks a lot for the help.