(08-03-2025 )wrench buster Wrote:  Greetings, I was working on a 2014 Cummins M2 that needed injectors (too much return) . I swapped out the injectors and the truck ran fine until I put the injector codes into the ECM. When I did that it started running rough and misfiring. Now the engine surges up and down and won't rev up. The fuel rail pressure and commanded pressure are about 11000 psi. The press relief valve is ok, the injector return is within limits. I did notice the fuel rail pressure drops pretty fast upon engine shut down, and the only active code is turbo speed sensor. I had another HP pump head and installed it but no change. I will look at fuel aeration tomorrow since it acts like there is air in the system. This problem is keeping me up at night. Can anyone shed some lite on this issue.

Thanks

(08-07-2025 )mikkhh Wrote:  Has there been something done to the ecm programming wise? Something mandate'd or more power added?

(08-07-2025 )wrench buster Wrote:  Hello, I ran a system pressure test today and it didn't hold within specs. I found inj # 1 was leaking bad when I turned the engine off. I thought alright I found the problem, however that would have been too easy. I replaced # 1 with a Cummins re-man and the rail pressure held within specs. I ran a injector return test under hi pressure and it was within specs. (80 ML) in 1 minute. I am really stumped on this one because it still idles rough and misfires upon acceleration. The HP pump produces 29,000 psi so I don't believe that's the problem. I am leaning towards defective injectors or an ECM issue. If someone can help me narrow this down I would very much appreciate your help. I have no codes, if it was an electrical issue I believe it would throw a code.It feels liike ALL cylinders are misfiring upon acceleration not just 1. When I do the cylinder cut out it seems like very little RPM loss on ea. cyl.

Regards Wrench Buster