i have a '91 f-250 5.8w it was running great and yesterday it started giving me trouble. it will run but sputters and dies. with the key in the run position i hear the fuel pump running constantly. the fuel pump relay starts clicking like crazy. so the pump stops and starts when the relay clicks. what can this be? this is my only vehicle and i am going crazy trying to find out what it is. how can i test the fuel pump relay? could it be the ecm?

 

just changed the fuel pump relay as it is the cheapest place to start. i figured that wasn't it and i was right. with the key on engine off the fuel pump runs steady and then the fuel pump relay starts clicking. the truck will start at times. the relay makes noise and the truck will run like crap and die. can anyone give me some help?

 

I don't want to ask a really dumb question, but, are sure there is adequate fuel in the tank?

If the pump is running, the relay must be OK. If it's not building up pressure I would think it it is a bad pump or lack of fuel. I am assuming the pump is in the tank. I am also assuming you're not pumping gas out of a line somewhere.

 

i would check to see if it is keeping fule preassure

 

Chipperhead's comment about the fuel pressure meaning a bad pump therefor lack of fuel makes me think maybe the filter needs changing? but It really sounds like the pump might be giving up the ghost.

 

changed the filter last week when i changed the oil. yesterday i changed the fuel pump relay and it does the same thing as before. i have a feeling it may be the ecm, but dont know how to test it or if it can even be tested. i am going to change the fuel pressure regulator now. dont think it will make a difference, but the new one only cost me 3 dollars from my friend. anyone got any other ideas. i am going to do a fuel pressure check. hope that comes out right. and no fuel is leaking anywhere.

 

A pressure test seems like a logical step to me. In retrospect, maybe it could have been a first step.

If you determine that you need to access the pump, you may be able to expedite the job by cutting an access panel in the floor of the bed. Just be sure you don't cut any wires or hoses in the process. Inspect/replace the pump, and patch the hole. That may be easier than draining and dropping the tank.

Good luck,
Marty

 

pressure test turned out fine. i decided to go ahead and change the ECM. and that is what it was. so if the fuel pump runs steady you cant get the codes out of it. so i figured if it couldnt tell me what was wrong with itself it had to be the computer. and it was. thanks for all the responses.