I've recently installed a cummins 6bta 315hp in my boat. The engine is older (94') and only had 700 hours on it. My first sea trial my tach was maxing out at 3200 rpm. I realized my tach was not adjusted and used a strobe tach to dial it in. Second sea trial it only turned up to 2400 rpm. After a long steam it would only turn 2200 rpm. Changed all fuel filters and ended up running short fuel hoses supply/return into a 5 gallon jug to insure no fuel line restriction. Tested it again and it turned to 2600 rpm for a very short burst and shutdown. Primed it quite a bit and she started again. Pulled off fuel shutoff solenoid and ran it up to 26/2700 and same result she shutdown and had a lot of air in the system. I am almost certain that I am not over propped. From reading threads on here I believe I may have a lift pump issue? Has anyone else experienced this? It starts and runs beautiful but I can't get an accurate WOT rpm.

 

I have a boat with 2 Cummins 6BTA m2 and have the same problem in an engine.
Does not exceed 1900/2000 RPM.
I would be helpful to know if you solve this problem.
And if so tell me how.
Thank you
Alejandro Stedtfeld
(from Argentina)

 

Diesel Auto Power Premium 3K And 4K Governor Spring Kit - 12VGS3K4K - Diesel Auto Power, LLC and some heavy duty valve springs.

If you have enough turbo/air to spare you can also go bigger in the injectors.