2003 Cummins 3500 H.O 6 speed running issue PLEASE HELP
 

Hey all, New to the forum but have been browsing for a while. I am having trouble with my cummins, here is a list of what has happened so it's not a jumble

-Originally would start idle surged, then leveled out drove great this lasted a few days from purchase
-Driving to work one morning truck surges a few times then dies no start
-Towed to my shop tried cranking on it the next day a few different times with no start
-the next day I pulled the fuel filter and it was black and clogged, replaced fuel filter fired right up, let it run for 20 mins no issue
-Drove truck the next day about a mile to lunch, after lunch fired it up drove 30 feet and died no start
-Got it back to shop let it sit a few hours fired right up, dies after idling about five minutes then will no start, after about twenty minutes will start idle for five then die
-Replaced fuel filter again with Dealer filter, starts, idles for 5 then dies.
-Also I should add if i keep the rpm above 800 it won't die at all when it is running but if I let off the gas it will idle for a few seconds then die, just idling on it's own though it will only idle for a few minutes.

Any Ideas?

Damn that's a pain! Did you check the lift pump pressure? Put a gauge inline by the CP3.You may need a new pump I would get an after market air dog or fass system!

I haven't checked it yet, The lift pump on mine is in tank I believe. I don't see a lift pump on the back of the filter resevoir. I am thinking that is my next move is line pressure to the CP3 injection pump and see if it dies off, that is a great idea, thank you for that. I was also thinking it could be bad fuel but I would have different issues and I know the CP3 is self bleeding so air in the lines couldn't be an issue.

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Don't mean to overpost, but I do know if the lift pump fails the CP3 should still have enough pressure to keep the fuel moving under a higher rpm. So that may be why the truck will stay running at higher rpm then idle ... I don't know just spit balling here.

If you still have issues check the torque on the crossover tubes to the injectors. if they are not to spec of 37ftlb?? that was the problem with my 03 with nearly the exact problem, no codes.