94 F150 motor troubles
 

I have been having issues with my truck and was hopeing somone could give me an Idea as to whats going on. My truck will run fine for about 10-15min after its started. Then it starts to stutter, bad. It gets worse as I drive longer. It all started at the sand dunes. I'm not sure what happened, but the air filter was clogged with sand, so thats where I started. I had to put a sock on the mas air sensor, replaceing my KandN filter, to limp the truck home. I have replaced the throttle position sensor, cleaned the mas air sensor, took the cats off and made new exhaust, and checked the timming. The check engine light is NOT on, so the code reader doesn't help me. By the way its a '94 302 V8 with 95,000 miles. Anyone got any ideas? Thanks for any info you guys can give.

Try some carb cleaner, spray down air horn and open the thottle plate while spraying, let soak for about ten minutes. Start engine to clear out the intake and spray some more while idling. Spray some more while opening throttle, no need to do a John Force show just crack the throttle open a few times to force it down those long runners. That should clear any debris out of the intake.

If that didn't do it check your fuel press on the rail(need to buy a gage) should be between 32-38 psi. If that OK then take a look a your fuel press. relay. If the coil in the relay goes you'll get the stumbling your experiencing.(located in the fuse box under the hood, five pin relay costs @ $28) Don't quote me but I think it the second one from the left, aft row. Can also check by pulling it with the engine running, it'll kill the motor.
Hope this helps, let us know if any of it worked.
Ed :cool:

Sand got the air and fuel it gets the ignition too. IMHO. try the plug wires and plugs if they are right go back to the fuel system.

tom

I have also replaced the spark plugs and checked the wires. I need to go get a fuel pressure gauge, and then I will check that. I also heard about the relay, but wasnt sure which one it was, and just never checked on it, but if you think that could do it then I will check that also. Thanks a lot for the ideas, I'll let you know what happens.

Ok- so I checked fuel pressure, thats the problem. The pressure dropped as low as 10psi. So I had my fuel pump warrantied, its an aftermarket in line pump from napa. I should have mentioned that I have a 60 gallon tank, but my friend has a fuel cell with the same pump and has never ahd problems with the pump. Anyway I replaced the pump, moved it below the level of the pickup in the tank, and doubled the wire thickness going to the pump for more power. I thought maybe it was not getting enough power. I swapped the relay under the hood with the horn relay, so thats not it either. So the only options I have left is fuel pressure regulator. My only other question is, I extended the harness that runs along the drivers side inner fender, do you think I should get into that harness and check that stuff out? It is completely taped up so I dont think thats where the problem is. If someone out there knows if there is anything in that harness that would cause problems let me know.
Thanks again.