Ive got an 89 with a 305 and tbi. I have theses times when i shut off the car and the fuel pump is still running. It will go off after a while but i noticed that under this condition, the longer i drive it the longer the fuel pump will stay on for. Also as the longer i drive worse the engine runs. EX...It has really bad hesitation and will run real rough. Eventually when i drive it long enough it will stall and then wont even run at all. So while its not running the fuel pump is running but eventually when the fuel pump shuts off it will fire right up. Whats goin on here? Have had thoughts about a faulty fuel pump relay or a fuel leak but im not quite sure where to start.
I think I would start with the fuel pump relay. If the contacts are arcing they can kind of weld themselves together and stick. Also if they are arcing they may not be giving the fuel pump full voltage when the car is running.
that sounds like a very logical scenario. i've seen it happen with fan relays, so i'd imagine that the fuel pump relay would do the same. i will ask you as i do with any other guys' late model cars, is the Service Engine Soon light on? if so, then you need to scan the computer for codes to retrieve them. if you have a Haynes manual, they tell you very clearly how to do this procedure. hope this helps.
The compressor at work tried the trashed relay trick and would over preasure. Cleaned the contactss with a hammerd flat wire and cruised on with the 120psi shut off and on and off switch working instead of being frozen on. I don't think the new designs allow cleaning relay points. Submit to the force of earlier generations. They are calling you.