Hello, I am having an issue with my 04 5.4L expedition with 165k miles. Randomly it is hard to start, you have to crank it a long time before it will turn over. After it does start performance is normal. No black smoke, other than a little during a cold start warm-up. I hooked up a fuel pressure gauge and it quickly climbed to 56 psi and stayed there. When I turned it off, it went to zero psi In a few seconds. Despite starting it many times, I could not replicate the long-cranking problem. I think it is a bad check valve on the fuel pump, but I want to rule out the pressure regulator first. I also need to know where the fuel pressure regulator is located. If it's in the tank, I will probably replace both it and the fuel pump. I am in need of some advice- should I go ahead and replace the pump, regulator, it both? Do I need to do more testing? Thanks so much for your help, Matt.

 

That sounds like the check valve in the fuel pump is bad. Nothing to do except replace the fuel pump. To avoid burning up the starter just flip the key to the RUN position a few times before you actually try to START it and that'll build up the fuel pressure before churning the starter over, and it'll fire up quick like normal. Just until you replace the fuel pump.
I have seen people just put a separate brass check valve in the rail feed line under the driver's floor area. That would probably work if you don't feel like dropping the fuel tank to change out the fuel pump. You would need the brass check valve and 1/4 NPT x 5/16 barbed fittings.

Brass check valve for fuel line


2004 Expedition Fuel Pump Assemblies at Rock Auto

 

I went through this 2 years ago with my 03. Do like Hamfisted says and cycle the key on-off a couple times to prime the system until you get the fuel pump replaced.

 

My 1999 had the same issue and it was the fuel pump on mine. Had the issue for over a year like that.