I have a suspicion that it is the fuel pump or its integrated check valve. What should the fuel pressure be in a properly running XP? How long should the pressure stay in the system after the truck is shut off?

Thanks.

 

I believe 35 to 40 psi . It should hold for a few min. 5 , I think . if it drops fast , a problem for sure .Also ck filter for restriction , if it has one . Filter may be by the tank under a plastic cover at the frame rail .If I remember correctly .

 

Thanks. It has a brand new filter, I will hook up the gauge tomorrow. Not looking forward to dropping that tank.

 

We just replaced our pump for a bad check valve -- I think it should hold some pressure for a very long time -- keeping the line packed. Our symptoms were 1st long crank times after sitting a few days, down to eventually just over night. I happened to take it on some errands and parked front facing up hill and the final straw was it took minutes of cranking to get it to finally catch. So don't park yours up hill until you fix it!

We had a near full tank of gas so I had a good local mechanic do it and lucky I did. He got the whole thing back together with a brand new Ford pump and guess what?! The new pump was bad from Ford!

So he had to do the whole job twice. I would have been spitting bullets if it were me.