Hello, Being new to this I will give it a try. I have a 1991 Ford F150 - 302 EFI, Auto trans. 2 wheel drive. It falls flat on its face after starting. Idle changes, engine light comes on then sputters and no power. This truck sat for a while but engine runs great when it runs. I have put new plugs, wires, coil, fuel pump relay, fuel pressure regulator, cap and rotor. Any thoughts? The problem follows whatever tanks I run on. When it dies and you try to restart the fuel pump sometimes will not shut off but will start and continue to sputter. If the fuel pump shuts off when you try to start then it will run without problem, maybe all day or down the road. Would appreciate any ideas.

Thanks, Soakem

 

that sounds like either bad gas or a relay sticking could be both. welcome to the sight

 

So we all can get on the same page.
When you turn the key on you should hear the fuel pump run for 1-2 seconds and if you do not attempt to start it the pump is supposed to stop. The computer supplies the ground for the fuel pump relay. Once the computer gets an RPM signal from the ign syst it energizes the fuel pump relay for the vehicle to run.
Some Fords have one fuel pump in each tank only and others have a low pressure fuel pump in each tank and a Hi pressure pump on the driver's side chassis rail aprox below the drivers seat. How they determined which one should have which, I never found.
A suggestion, rent or get hold of a fuel pressure gauge and connect it to the schrader fitting on the front of the fuel rail. The 302 engine spec for fuel pressure is 30-45 PSI.
If you have that it should eliminate some question of enough fuel or not. ( There is always the volume part and you would need different equip to get that).
If your vehicle has a hi-pressure pump it could explain why performance is lacking no matter which tank you select.
You didn't mention the fuel filter , did you change that?

 

Hello, Thank you for your reply. Yes, I did replace the fuel filter. I am starting to lean toward the computer or a wire problem. I use an 89 octane fuel in this truck and it runs great when it wants. I will check the fuel pressure again and try to catch it on a power loss.
I am all ears on this.
Thank you, Soakem

 

You did mention that the check engine lite comes on. There should be some code or codes in the computer. If you can get them it will provide some direction where to look for the problem. There are hard codes that will come up without starting the engine. Then there are continuous codes that are in the memory. Those years had a dynamic testing program that the computer ran automatically. It ran the tests and gave the pass/ fail results. Troubleshooting them was pretty easy. Might pay to look into that.

 

Thank you, I will check the codes and fuel pressure on Friday.

 

Thanks guys for the replies and ideas. Fixed the truck today. My son in law and me pulled the computer for a look see and found 2 capacitors burned up and leaking. Found some info on here regarding these capacitors and found replacements at radio shack. Soldered new ones in, installed and truck has not failed me so far. This has been a lesson and $3.00 sure beats $300.00.
Thanks again for your help. What a valuable site.
Respectfully,
Soakem

 

Were you able to trace the circuit back to the pin numbers of the computer and see which circuit was involved. Might help prevent a repeat failure.

 

glad to hear that you got it fixed. good luck with it

 

I am with the thought that the capacitors involved had lived out their lives being the truck is this old. It was plain to see when removing the cover of the computer that the capacitors were shot. Ford apparently had seen this problem and corrected it on subsequent years but left it to the owners of the 91's to figure it out. At least the new parts that I threw at the truck were needed anyway as it runs great. Heat and age was it greatest enemy.


Soakem