Just trying to get some things straight in my mind about the CR. I know that when the truck is running that the CR pressure can go fairly high (~20K psi). When the engine is shut off, what happens to that pressure? Does the pressure go down to zero or is some pressure maintained? If it does go down to zero, by what mechanism does this occur? Thanks - Curtis

 

Basically there is a rail relief valve- should not bleed down. The only other thing that would hold pressure ( really won't be any pressure , but volume ) is the FCA - Fuel Control Actuator. It is bolted to the back of the CP3 pump. The lift pump will build 7-10 psi of pressure with the key on, then the CP3 engine mounted high pressure pump does the rest.

 

I'm just going through a list of items to check for hard-start issue. Seems I can plug the Fuel Pressure Relief Valve on the common rail and if it cranks right up, it is probably by-passing fuel not letting the rail pressure get high enough for the ECM to tell the injectors to fire up. I'm not sure abouthow to test the cascading overflow valve on the CP3, but I hear that some folks have removed, cleaned and replaced it. I will take off the FCA to see if it rattles like it should. I have no idea if the Crank or cam position sensors are affected if they get hot, but my hard-start problem seems more prominent after I have driven for 30-40 minutes than it is upon a complete cold start. Thanks - Curtis

 

The pressure bleeds off thru the injector fuel return line when the system is powered down, which could be causing your hard start condition if it is bypassing too much fuel.

 

I am having the same problem i took my truck to the dealer today he says every one that has had come in like this the culprit has been a bad injector causing the bleed off. Once the pressure is lost starter crank speed is not enough to buil the pressure back up to start the truck. I guess i will know this afternoon.