1984-1986 Mercury Force 9.9 and 15HP Outboards Service Manual, Page 14Get this manual
SECTION
FUELPUMP FUEL PUMP
GENERAL
The information in this subsection concerns the removalrepair, and installation olthe fuel pump back and forth with changes in the crankcase pressure of the No1 piston This pressure is transm itted to two reeds, an inlet reed and an outlet reedmounted on plate inside the fuel pump When the diaphragm flexes inward it opens the inlet reed and allows fuel from the fuel tank to enter the pump through fine mesh screen filterFigure 1When the diaphragm flexes outward it closes the inlet reed and pushes the fuel through the outlet reed and out of the pump to the carburetor