Machine Serial number YQU4681 Cummins 5.9 I have a Kobeloc 200LC Mark IV. Two weeks ago, the RPMs started dropping then would go back up. I replaced all the filters (both fuel filters and air filter)- still fluctuating. I replaced the fuel lift pump and it immediately made a big difference - the machine ran great. Now after 30 hours of run time, the problem has returned. I am not sure what to test or look at now? Any help would be appreciated.
When the RPMs drop, none of the linkages on the injector pump move. They remain in place as the RPMs drop (if this helps).
I'm sure that you have already checked and drained the water from the fuel/water separator?
My 2004 ED150SRLC has a tiny screen in the banjo bolt on the water separator inlet connection. It was plugged at less than 500 hours. Could there be one in yours?
Yes, that helps a lot with the diagnosis. My guess is that your machine has a faulty stepper motor that controls the throttle lever. I suggest that you perform the "A adjustment" first. Please see attached file for more detail.
Well, it ended up being one of the batteries. The battery was over 5 years old and would not even register on the battery charger. My guess is that it was pulling current away from the computer. Changed the battery and the machine is working good again.