93 4.0 crank no start

[SCMoore]

This one has my local garage guy stumped. I’m hoping someone here can help sort this out. My 93 4.0 will crank but not start after it sits for a while. If I turn to key on and wait for the fuel pump run run and stop, then key off and repeat 3 times, on the fourth turn of the key I can turn to start position and it fires right up and runs like new. Works every time. If I get in and just try to start it like normal, it cranks and cranks but will not start.
It seems like it’s losing pressure over time.
Fuel pressure is good once running but drops off after sitting for a few minutes.
new FPR, fuel pump, plugs, wires.
Any suggestions where to look next?

 

[RobbieD]

Fuel pressure is good once running but drops off after sitting for a few minutes.
new FPR, fuel pump, plugs, wires.

That sounds like the FPR. These days, "new" doesn't necessarily mean "good".

 

[SCMoore]

That sounds like the FPR. These days, "new" doesn't necessarily mean "good".

Is there anyway to test those things?

 

[RobbieD]

Is there anyway to test those things?

I wasn't sure so I looked at the shop manual. I also wasn't sure where the check valve is, that keeps the fuel pressurized.

According to the shop manual, the check valve is in the fuel pump. It's function is to maintain fuel system pressure after the vehicle is shut down; which, quoting the manual, "helps prevent hot starting problems".

So if your fuel pressure is good while running, but won't hold after shutting the engine off, the check valve in the fuel pump would be suspect.

 

[SCMoore]

How long should the fuel pump run with the key on the on position? This thing doesn’t stop running.
I can hear the fuel running through the FPR. The truck won’t start now without starter fluid.

 

[SCMoore]

Update: I had some bad gas for one thing. That is working it's way out.
I'm still having an issue starting it in the AM. Once it runs in the AM I can start it throughout the day. I put a second FPR on and it started the next morning as it should. But this morning, it's back to same thing. I noticed that the check engine light stays on while I'm cranking. Is that normal?
It will go out once I finally get the thing started.
Does anyone have any further suggestions?