Hi everyone. While testing my 290lc hydraulic pressure per the manual, one pump is at 2500 psi and the other at 500 psi at 1/4 throttle. When I lift the boom, one pump goes to 5000 psi and the other stays at 500 psi. Does anyone know what controls these pumps ?They are a variable output swash plate design.Thanks.
Normally, it is controlled by PSV (Proportional Solenoid Valve); each pump has its own control PSV. When the electrical part is damaged, it can switch to hydraulic-mechanical control exactly like the SKxxx dash one. you can refer to its hydraulic diagram attached. Good luck.
Are you sure you checked the right ports it sounds like you may have tested the pilot pump