Chrysler 100, 115 and 140 HP Outboard Motors Service Manual, OB 3439, Page 38Get this manual
Subsection
_ FUELPUMP
GENERAL
The information in this subsection is concerned with the removal, repair, and installation of the fuel pumpThe 100 and 115 H.Pengines have single fuel pumpThe 140 H.Phas twin fuel pumps
DescriptionA two stage diaphragm displacement fuel pump is used to lift fuel from the fuel tank and direct it to the carburetors
changes in crankcase pressure of the NO3 cylinder make the diaphragm flex in and draw in fuelA fine mesh screen filters the fuel as it enters the pumpAs the diaphragm flexes out, it transfers fuel internally to the second stageThe second stage delivers fuel to the carburetors (or to upper fuel pump on 140 H.Ponly) when changes in crankcase pressure of the NO4 cylinder make the diaphragm flex out