I got a Hitachi ex35 that all functions are slow. All hydraulic filters have been changed including pilot pressure filter and fluid. I also pulled out the suction strainer and it was clean.I bought a hydraulic flow tester and when hooking into pump one or two machine will push about 5 gallons at about 1000psi at fast idle. Once you get to about 1500 psi it drips below 2 gallons a min. Service manual says at 2000psi min. Acceptable is 6.6gpm and at 3000psi minimum acceptable is 6.4gallins. I took pumps off and sent them hydraulic express to be rebuild 2k later I still have the same issues. I checked all hose clamps going from suctions to the pump and all was tight just looking as to what to look into next
Check the relief valve on the control bank, take it out and give it some cleaning and the readjust..
Are you talking about the relief valves on the valve body it has reliefs for each pump checked pumps one,two and three and all three are set to max of 3850psi or is this a different relief
How bout main relief valve before all the pressure entering the valve body.
From what I see and what schematic show pumps one,two and three go straight from pump to valve body and relief is blow the lines the pilot pressure pump goes to a separate manifold but from what I read the pump should adjust flow if supply pressure from pump three increases flow should increase on pumps 1 and 2
Have you tried adjusting the flow rate adjusting screw? Sounds like your pump is destroking too soon.