I have a 99 F150 5.4. 96,000 miles. Been running great, one morning truck will start but shut down in about 5-10 secs. I borrowed a code scanner but didn't retrieve any codes. I have replaced fuel filter, pcv valve. I have checked cam pos. sensor, voltage at fuel pump relay and at fuel pump. If I spray starter fluid in the intake truck will continue to run. PCM, and fuel pump relay working. It's like something is telling the fuel pump to stop? I am hoping I am overlooking something simple and the problen isn't the PCM. Any Ideas?

 

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i would check the pressure regulater or injectors. if the pump is got power and is pumping. then there is the only to thinks i can think would cause your problem.

furrby

 

Is there a way to check the Fuel Pressure Regulator?

 

have you cleaned the idle speed motor.it wont set a code unless it is shorted.actuators usually dont tell on them selfs,if the pcm tells it to work it does.

 

I have just finished replacing the IAC valve -no luck, Idle speed motor?

 

I have looked in Haynes Repair Manual, no mention of Idle Speed Motor? Not even in wiring Schematic?

 

what about the crankshaft pos. sensor.

 

the people on this mess. board call it a idle speed motor,in the dealer world its called a iac

 

get a fuel press. gauge and see if the fuel press. is falling off. you could have power to the pump but the pump could be getting weak.

 

Sounds like a weak fuel pump - even though its pumping, the volume and pressure might not be enough to run the truck.

 

There is a filter in the tank attached to the pump. You might have got a tank of dirty gas and it plugged that filter. You can try blowing with low pressure air backwards thru the fuel outlet hose then try running the motor. If it keeps running then you will have to drop & clean the tank & replace the pump cause the filter will clog up again real soon.

 

just a silly question but did you check to see if the PCV hose was in good condition when you changed the valve as these are known for accumalating vac leaks