My '03 will not start when hot. Replaced the lift pump with a frame mounted unit with a bypass into the return fuel line. Then took it to a diesel specialist. They predicably indicated CP3 pump - replaced it, still same problem. Took it to Dodge last week - they say six new injectors and a new pressure relief valve. Scheduled to take it to Cummins shop next week - they seem to think it's not injectors, at least not all six. It's out of warrrantee and I've been running a quad box on 60hp setting. Any thoughts?
Thanks!

 

I would bet it's the relief valve not holding press. in the rail.

 

try shutting the quad to the stock position and starting the truck there, might be in my head but I think mine starts quicker hot with my box on stock, dunno why, but it seems to .

 

I've tried everything I can think of. I have the box unhooked right now - I don't think it made any difference. I plugged the pressure relief valve and tried it also, no difference. The diesel shop did return flow tests and said nothing was out of line. What are the flows supposed to be? Maybe I can check them myself. Keep the ideas coming - it's got to be something!

 

Have you tryed removeing the quad box?Could be a wireing harness problem.Does it throw any codes?

 

Pulling the box didn't change it. I did have trouble with the quad wiring harness in the past - it was causing surging and running rough. I cleaned up the ends of the plugs and added some dialectric grease, and it's been fine since.

I do think I've got it figured out, maybe. The Dodge dealer left me a test plug for the rail. Process of elimination - remove one injector line and plug it, see if it starts. It's starts fine with No. 4 plugged off. So, it looks like I need an injector, or need to tighten up a seal somewhere. What's the deal with that - are there any possible fixes other than a new injector? Thanks again for the help.

 

If you've narrowed it down to #4 inj.Then you are haveing a leaking problem.The cp3 can't build enough pressure to get the inj.'s to fire.Probably in the nozzle.The only fix is a new inj.Sorry for the bad news.

 

If I can get by with one injector I'm OK with it. Fuel filter upgrade?

 

Yeah.You have to replace the #4 injecter.& I'd definitly get one of those 2 mic. fuel filters on.Thats next for me too.

 

End of story - I ended up replacing all six injectors. I found a set of low mileage 2005 injectors on Ebay and purchased a set of 2003 50HP nozzles. Starts like it was new now. 2 micron filter is on it's way!
Thanks for the help