2003 cummins hard starting always. why?
 

Hey guys so my budy has a 2003 cummins with a smarty tuner, 4" exhaust and a airdog 150 lift pump.
he just had a south bend clutch 800hp installed and is getting ready to build it but now its started having a hard time starting. All the time cold or warm even after it was hust running. So we are thinking bad cp3?

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Or injectors? He is planning on taking it in to the shop but wanted to run it buy you guys first

I know this is not a current question for the guy who asked the question but I have found that the hard start is most likely the injectors. The injection pump "CP3" is a very well designed and simple pump compared to traditional mechanical pumps. The injection pumps on the common rail cummins/duramax engines will last 200,000 + miles if they don't get major contamination problems. The injector on the other hand are dealing with 26,000 psi of pressure and will begin to fail between 110,000-140,000 miles on the cummins. Hope this helps someone!

use a scan tool and look at the rail pressure while cranking and check it against the spec. PM me and i can look up spec for you. but my guess is bad injector(s)