Hi, I've got an '04 Lightning that fires up then dies. There are no fault codes. When you turn the key it starts straight up, then runs rough for a short while then dies. It will start up again right away but then repeats the rough run and die. It has around 45psi fuel pressure with KOEO and when it runs the fuel pressure drops right off. I've changed the filter (twice) and the pressure regulator in the fuel rail and it's still the same. I did notice that after each filter change it ran slightly longer before it cuts out.
Appreciate some help on this

 

Check your fuel pump resistor:

https://www.f150online.com/forums/sh...d.php?t=227200

Mine acted the same way when it failed. Someone said when you changed fuel pumps to a higher flow rate (like the 255 lph pumps), you need to change the resistance or it will overheat.

 

Hi DH, thanks for the reply and link, I'll give it a check, I've still go the OE pumps though, and I see from one of the posts in the link you left that the resistor is by-past when over 1/2 throttle, my one won't respond to the throttle anywhere

 

Sounds allot like the IAC valve since it starts right back up after dying.

 

Have you recently done anything to the engine? That sounds like one of your larger vacuum lines is disconnected.

 

Hi, it was the pump resistor, one of the wires had rusted off, put the two wires together as a check and it ran ok. I've ordered a new resistor. Thanks for your help.

 

Great! Glad to hear you figured it out.