Just looking for a second opinion here. 04 Expy with 5.4. Intermittently there will be a long start where I have to crank it over a good bit more than normal before it fires. Never happens with a completely cold engine. Only after the engine has been run a while and stopped and it sets for a few hours.

From my forum searching I figured it was the fuel pump check valve bleeding back and I still believe that's what it is.

I purchased a fuel pressure gauge and hooked it up and have been driving around with it for the last 2 weeks waiting for it to have a long crank. Go figure, it hasn't done it with the fuel gauge hooked up but here is what I have noticed that makes me think it's still the pump.

Most mornings after sitting all night fuel pump will only pressurize the system to between 25 and 35 lbs of pressure with the initial key on. Once you start cranking the pressure jumps on up to 51 lbs. and the engine always starts. On occasion it will push it all the way to 51 lbs with the first key on.

The bleed off on the system once the engine has stopped seems very unpredictable. Sometimes it bleeds to zero pressure in an hour and sometime it has held 10 psi overnight once.

Sorry for the long post just trying to get in all the detail. Do you agree it's probably the check valve in the pump?

 

Although the check valve is a good possibility, there's also the much less expensive fuel pressure regulator which can be leaking pressure back into the tank.