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Hello to everyone out there. I am an owner of a 2006 dodge 5.9 Cummins and like most on this sight have been experiencing hard starts. Here is some background on the truck I purchased the truck used from a single owner. When I bought the truck he provided me all the service history (all the paper work to include oil changes and tire purchase). I have owned the truck since 5 Mar 2021 single owner. When he sold me the truck he occasionally experienced an excess cracking to start truck. The first two weeks never experienced the issue. Then my wife drove the truck to run errands I had to go rescue her. When I attempted to start the truck arrived I noticed the truck batteries were dead. I jumped the truck. Had the hade the batteries tested they were bad replaced them and performed test on the charging system it checked out good. In the course of evaluating what the cause for the hard/no-start I performed the following test: Conducted the all flow tests, no leaking high pressure lines torqued injector to 43ftlb. Pulled injectors took to a reputable shop for testing, all injectors past all required tests (the shop that tested sated injectors noted they were bosh certified injectors). Replaced injector tubes (the dealer installed 6.7 when they replaced injectors at 140k). Replace Fuel control actuator and Fuel pressure sensor. Through the course of testing my fuel system this is what I am experiencing. Truck starts fine if below operating temperature (190 to 200 degrees F) at operating temperature and if it sits 10 minutes more then the truck will not start. If I let the truck sit and cool it will start with no problem (3 or 4 engine revelations and starts). I know this may not be a smart idea but it is something that I tried. I poured water over the CP3 pump to cool it down and the truck fired right up with minimal cranking. When the truck is at operating tempura and cranking the engine over in an attempt to start the truck the fuel rail pressure will not rise above 1,700 PSI. The pressure will fluctuate between 1,400 and 1,700 Psi never reaches 4K psi to start. Here is the question is the pump bad? From my understanding the pump either is good or bad and when it goes bad it will not start no matter the operating temperature. Or have I been led a stray and the pump does slowly fail? Has anyone experience these types of symptoms and if so was it the pump or have I missed something in my testing that I need to replace
 

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I think you found your answer, weak CP3. Electronics, when they fail is often when they get hotter. The old HEI GM ignitions were terrible for this happening.
 
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