Fuel pump problem????? Maybe?
#1
Fuel pump problem????? Maybe?
91 f-150, 5.0, auto, 4x4
Heres the deal, when I turn the key to on, the fuel pump should make a running sound for a second then stop, (it's priming), then when you turn the key the rest of the way to start it should start,,, right? Ok I turn the key on, and the fuel pump will not prime it just keeps running, on both front or back tank. I thought some POS stole the gas out of the tanks so I put more fuel in, same thing, will not start. I'm trying to sell this truck, I bought a newer one, but I need to get it running first. DO I need a new fuel pump, relay, what might be up here.
Heres the deal, when I turn the key to on, the fuel pump should make a running sound for a second then stop, (it's priming), then when you turn the key the rest of the way to start it should start,,, right? Ok I turn the key on, and the fuel pump will not prime it just keeps running, on both front or back tank. I thought some POS stole the gas out of the tanks so I put more fuel in, same thing, will not start. I'm trying to sell this truck, I bought a newer one, but I need to get it running first. DO I need a new fuel pump, relay, what might be up here.
#2
#5
#6
When a fuel pump keeps running when you turn on the key you either have a stuck close fuel pump relay or the clock in the PCM is not running. If the clock does not run in the computer then the fuel pump will not time out after one second and quit. Also if the clock is not running the fuel injectors will not be firing so the engine will not start.
The engine would start if it was just the fuel pump relay was either stuck closed or its coil wire going to the PCM was shorted to ground.
Sometimes this may also be caused by a bad PCM ground from the NEG post of the battery or lack of power on pins 37 & 57 but this is not very likely.
IIRC on a 1991 the PCM is unplugged under the hood and then removed from the drivers kick panel. There would be a number on the PCM's plug that the auto parts store can use to get you the right one. If should start something like:
F1T*- 12A650-**.
The engine would start if it was just the fuel pump relay was either stuck closed or its coil wire going to the PCM was shorted to ground.
Sometimes this may also be caused by a bad PCM ground from the NEG post of the battery or lack of power on pins 37 & 57 but this is not very likely.
IIRC on a 1991 the PCM is unplugged under the hood and then removed from the drivers kick panel. There would be a number on the PCM's plug that the auto parts store can use to get you the right one. If should start something like:
F1T*- 12A650-**.
Thread
Thread Starter
Forum
Replies
Last Post
Cadie9021
1987 - 1996 F150 & Larger F-Series Trucks
3
02-18-2012 04:07 AM
transamscirocco
1987 - 1996 F150 & Larger F-Series Trucks
6
06-28-2006 04:09 AM
slammed96
1983 - 2012 Ranger & B-Series
5
10-07-2003 09:26 PM