1965 Evinrude 90 HP StarFlite Service Manual, PN 4206, Page 16Get this manual
FUEL PUMP The fuel pump is of the diaphragm-displacement type, and is operated by changes in crankcase pressureAlternate suction and pressure in the crankcase are transmitted to the pump diaphragm through flexible hoseSuction created on the upward stroke of the piston causes the diaphragm to displace and draw in fuel through the inlet valveOn the following downward stroke of the piston, crankcase pressure flexes the diaphragm in the opposite directionThe inlet valve is then seated, preventing the return of fuel to the tank, while the discharge valve is opened, allowing fuel to pass to the carburetorFuel is drawn through fine mesh filter before entering the pump to remove impuritiesSee Figure 3-5" -