I have a 93 F150 XL 4.9L . If the truck is cold, I start it up and drive less than 10 minutes and park it and try to start it with in 10 minutes, it won't start. It will turn over, but it fails to start. Sometimes you can just hold the key and keep it turning over for several miutes and then it will start, some times you can try for five minutes then turn the key and it starts with no problem. If I drive the truck for an extended period of time (greater than 10 minutes) this "no start " has not happened. During the no start sessions, I can remove the air hoses from the throttle body and stick a screwdriver in the butterflies and only on one occasion did it provide a start. More often than not, I am stuck for several minutes. I thought if it were flooded with gas, once it did start, it would stumble and spit.. But it starts just fine and runs as if no problem ever happened. I replaced the coil, cleaned the cap and rotor, changed the plugs... Cleaned the throttle assy.... What next? The truck will always (knock on wood) start when cold or after driving for extended periods of time. It seems to be associated with short trips.

Thanks,

Justin

 

Are you getting spark when it wont start?

 

Most of the time I am alone when this happens so I don't have a way to tell if I am getting a spark. If it were not not getting a spark, what would cause that? I replaced the coil, what else should I replace?

Justin

 

Ignition module or the "pick-up coil" inside the distributor. But both of them are about $40 a piece, so i would make sure you are NOT getting spark before i replace them. Also, can you hear the fuel pump run when it wont start?

 

I do here the Pump start. That was my first thought. It is odd, when the truck has this problem, when it does decide to start, it fire right up and runs fine. I don't think it is flooded, whould it not stumble and sputter for at least for a second or two after starting? If you had to pick one of the two electrical parts, which one would you place your money on first?

 

Module goes bad more often than the pick-up coil

 

If it were flooded, holding the gas pedal to the floor should allow it to start. When cranking, the ECM reads a maxed TPS signal as meaning "Flooded", and shuts off any fuel from entering. It could be a sticking air bypass valve, or a sticking EGR valve. You should try and retrieve any codes from the ECM. It would also be a good idea to check your fuel pressure, both while cranking and after you turn the key off. I have a hunch it's a lack of fuel, rather than too much, that's causing your problem. To verify, next time this happens, after a minute or two of cranking, remove a spark plug and see if it's wet.

Take care
~Chris