komatsu pc55 hydraulic pump staying stroked at start up ? Was told by komatsu mechanic i needed new pump i installed the new one it still does the sam

[venomslookalike]

komatsu pc55 bought it 3 months ago its a gray machine . I took it to a komatsu mechanic because the pump is staying stroked at start up with low power . I was told i needed a new pump so i purchased a new pump and its doing the same thing .The only way i can get it to start is by adjusting the swash plate angle with the screws on the side of the pump .Does anyone have a idea were to start looking ?

 

[Kobe Steel]

See my notes in this post about a similar issue with the pump standby pressure being too high

https://www.heavyequipmentforums.com/threads/pc55-unload-pressure-too-high.118651/#post-1321270

Best regards

 

[Marcrus]

Cap the ls line to the pump and put a gauge in it, they can crack passage in control valve. If load sense goes high then the pump will too.

 

[venomslookalike]

I have an update i took the main control valve off and found the LS bypass spring was missing and someone put paper towels in its place .So the entire thing was full of paper blocking things off . Now it starts right up and every thing was working until today i went to move it every thing worked for a little bit then i lost every thing but the blade and fwd and backward . Im getting around 700 psi unloaded and 500 psi from the pcc valve . Its a PC55MR-3 any help would be appreciated . Thanks