I have a 1990 F150 4X4, 5.0, auto, duel fuel tanks. When truck operates correct, when key is turn on I hear fuel pump run for about 1 second then cut off, truck then starts. For the past week, when I turn key on I hear pump run, sometime for 2 min. before it cuts off. Truck will not start when pump is running, it will only start when I hear pump cut off and relay pick. Sometimes the pump never stops running (this happens with both front and rear tanks) I can start truck, it will only run if I gas the truck, engine warning light is on. After gassing the engine for a few seconds the engine light goes out and the truck will idle. Changed the fuel pump relay, still have problem. Took it to dealer, he said fuel pressure is too high, 49PSI. Dealer chaged fuel pressure regulator, still have problem.
I still think it is a fuel low pressure problem. I think I am losing pressure and having problems charging the fuel rail.
Thanks for any help.
John Burke

 

have you replaced the filter? also I would have the pressure checked at another reputable shop, on both tanks. don't forget about Ford's recall on fuel pump cross over sender/valve. This issue I would have the dealer check. My recall says 12 yrs/150k miles.
'91 Lariat 5.0, 3.55 mint

 

pross,
Thanks for your rely.. I changed the filter today, a ton of junk came out. I don't know why I didn't change it before, it was a $7 part. One reason I didn't mess with it is beacuse the dealer told me it never needed changing. I changed it years ago when the truck had 36K miles. I think you may have found something. Will give it a few weeks then post back.
Thanks.
John Burke