Well, my 04.5 first started off with a bad injector. After replacing that, found out the fuel transfer pump was out. Then the CP3, then the APPS. All has been replaced including fuel pressure relief valve. Still the truck looses pressure once warmed up. CP3 pump is putting out plenty of pressure but some how im loosing it in the system.. Eventually it gets worst and worst. Anyone have a clue of whats going on?

 

If you are losing rail pressure, then I'd look at a pressure relief valve, a rail pressure sensor, or an injector.

Have you taken it to the dealer and had the scanner hooked up? It will tell you what the pressure is at idle.

How is your oil? Any fuel in it?

 

Yeah the pressure is good all around.. once you start driving is when it goes to crap. the relief valve has been replaced.. unknown about the oil.. its like trying to find a needle in a hay stack..

 

If your oil smells like fuel and is diluted, then you have a leaking injector.

What about the rail pressure sensor?

 

Injector cross over tubes will leak pressure back into the fuel return once they are warm if not torqued correctly, or o-rings bad, or not sealing correctly.

You should be able to see the high return with and injector fuel return test.