1991 Johnson/Evinrude Models "EI" 40 thru 55 Service Manual, Page 311Get this manual
Modes of Operation UP
1When the UP button is pressed, the pump rotates in counterclockwise direction2Fluid pressure opens the UP check valve mechanicaJJy opens the DOWN check valve
and moves the pump control piston
3Fluid pressure is directed to the bottom of the cylinder to move the piston UP4Low pressure fluid leaves the top ofthe cylinder, moves through the open DOWN check valve, and returns to the pump 5To allow for the volume differential caused by the piston rod, additional fluid is drawn into the pump from thp reservoir6When the piston is completely extended, the UP relief valve is mechanically opened to protect the unit from extreme operating pressures7When the unit is operated in the UP direction or when the engine is running in FORWARD gear, the following components must hold pressure: Up check valve Up relief valve Impact relief valves Piston O-rings Expansion relief valve External fluid leaks