1990 Johnson Evinrude "ES" Cross V 88 thru 115, 150 thru 175, P/N 507874, Page 327Get this manual
Trim "IN" ITiit "DOWN" Mode
When the hydraulic unit is in the trimin"tilt "down" mode, the hydraulic fluid is routed in the following manner:
1Hydraulic pressure is directed to the reverse lock check valve causing the piston to open the trim check valve
side of the pump control piston
2 Fluid then opens the reverse lock check valve against very light spring tension and flows through the valve to the top of the trim and tilt cylinders3 Fluid returning from the bottom of the tilt cylinder opens the trimtilt separation valveflows through the open valve, then through the open trim check valve and back to the pump4 Fluid returning from the bottom of the trim cylinders flows through the open trim check valve and back to the pump5Because of the volume of fluid displaced by the tilt and trim rods, less fluid is required above the tilt and trim pistons than is being supplied to the pump from beneath the pistonsSome of the fluid from the outlet side of the pump is returned to the reservoir through the trim-down pump relief valve