my problem started months ago when i could drive some where,and get back in my truck,a 91 ford f150 lariat with 5.8 and try to start it,no fuel pump hum.I would wait couple hours and come back and it would start up.It may do it again the next day or next week.I finally put a fuel pump in yesterday.Started it up,it idled o.k.,then took it for a test run,i noticed the performance was not the same,it was sluggish and got worser the more i drove it like it would not take the gas.After a few minutes i could not put my foot on the gas pedal,because it would just die.I let it pull it self home with a hope and prayer.Before i changed out the fuel pump,the truck ran super,no problem.Fuel is getting to the rails,i am getting spark,it will idle if you hold a little gas to it.IF you don,t it will die and may not start back up until later.I do hear fuel pump hum when trying to start it.Could it be time for ecm.

 

Have you pulled codes? If not, I would definitely start there since you can get a good code reader from Amazon for $25 (I use the Innova OBDI reader). If you get different sets of KOEO codes over a couple of days (even without getting a PCM fault code) then that can be a sign that something's up with the PCM. Also, before buying a new PCM I would pull the old one , open it up, and have a look. I did and found three capacitors that had leaked and corroded the circuit board. The realization was actually nice since I had been tracking down intermittent problems for weeks. Strangely, seeing the blown capacitors clearly indicated that the PCM was dead. I did some research after talking to a mechanic friend who said that the A1 Cardone remans (the easiest brand to find) failed frequently. The short story is that Protech Auto Systems had the best reputation for quality with friendly and helpful staff (http://www.protechautosystems.com/). They were a little more expensive than the others, but they claim that they replace all of the failure-prone components (including the capacitors that leaked and failed in my original) and bench test before sending. I just got their reman this past week and installed it yesterday (they also give it a nice anti-corrosive paint job!). My truck is running better than it has since I bought it a few years ago.

 

i put a used ecm in it after i first bought it,because the fuel pump was running all the time and relays were chattering and it would not run,but afterwards she ran like a champ,no problem,up until recently.Maybe time for one.

 

well i went and bought a remanufactured ecm for the truck.Installed the ecm,ran like a champ with plenty of power and within 10 minutes went back to running like it was starving for fuel.I took it off and put the old one back in now i am back to square root one .Any suggestions?

 

Just curious, have you changed the filter?

 

yes i have.Now thinking of ignition starter switch.What do you think.

 

Possible, first clear the inertia switch. I found mine on the '87 above the clutch pedal.

 

inertia switch is working.Pump will run some time and sometime wont.I am in a maze over this truck.

 

Have you pulled codes yet? Getting a better idea of what's going on will make it easier to fix the problem since your truck's issues could be caused by a number of component problems.

 

check engine light has never come on,it works when starting up,thats what make me believe some thing is interrupting my fuel pump from time to time.I bought a new ignition switch and key lock switch and will see if it works and remedy the problem.If not i will buy a ob1 code reader.What if it shows no codes?