I recently purchased a Komatsu PC50MR2 with 8500 hrs to use primarily on my farm. When I first bought it, it ran fine, but now the boom lifts slowly, and bogs the motor down. I have changed all fluids and filters. Removed the fuel tank, cleaned and flushed it as well as the fuel lines. I’ve also noticed that the left track motor seems weak, but if I pull back on the stick slightly, it gets full power but also bogs the motor. The boom won’t change at all with other functions. I have to feather it constantly in order to lift a bucket of dirt. I have a hydraulic brush cutter for it, and when I have the cutter running, I can’t lift the boom at all. When I release the pedal, the boom comes up right away. There are no leaks on the machine anywhere.
Good day I suggest if the motor has had dirty fuel it may be time to service the fuel system, pump injectors. If the machine is new to you check out the compressions - max. revolutions - turbo if you have one. Kind regards Uffex