Chrysler 20 and 30 HP Outboard Motors Service Manual OB 3435, Page 36Get this manual
FUELPUMP GENERAL
The information in this subsection is concerned with the removalrepair, and installation of the fuel pump changes in crankcase pressure of the No.2 cylinder make the diaphragm flex in and draw in fuelA fine mesh screen filters the fuel as it enters the pump As the diaphragm flexes out, it transfers fuel internally to the second stage DescriptionA two stage diaphragm displacement fuel pump is used to lift fuel from the fuel tank and direct it to the carburetorThe first stage draws fuel from the fuel tank when The second stage delivers fuel to the carburetors when changes in crankcase pressure of the No cylinder make the diaphragm flex out and send fuel to the carburetors