I have a 1991 mustang gt automatic transmission. went to start it one day and the fuel pump just kept running, wouldn't prime I guess, replaced pump and strainer, filter, pressure regulator, relay switch under the driver seat and made sure the button in the trunk isn't tripped. checked and I have no injector pulse either. checked all my ground wires (I think) any suggestions????
You never said what happened after you put the new fuel pump in... Does it do the same thing? Key on, fuel pump continuously runs?
There is no fuel pressure switch or anything that tells the computer the fuel system is primed. The computer is just programmed to run the fuel pump for 2 seconds every time the key is turned on, and to run the fuel pump anytime it is getting pulses from the distributor pickup(aka the engine is running or turning over)
SO if the fuel pump is just constantly running when you turn the key on, I would say that the computer may be bad itself. Sounds like something went wrong inside the box and its just constantly running the fuel pump, but otherwise dead......weird.
There is a pin on the diagnostic connector that, if you ground out, runs the fuel pump. Maybe that wire is shorted to ground? Thats why the fuel pump is constantly running? Im not sure if that would disable the computer or not though, so it doesnt exactly explain why you dont have injector pulses.
Sounds like a bad computer...they typically only fail once something outside destroys them though...so maybe pop the computer out and open it up carefully and see if has had water intrusion or not. Water wont kill the computer right away, but if it constantly gets wet over a long period corrosion will kill em.
