1987-1993 Mercury Mariner Outboards 70/75/80/90/100/115HP 3 and 4-cylinder Factory Service Manual, Page 92Get this manual
2Install check valves and retainers into fuel pump body Step-by-Step Reassembly
IMPORTANT: ALWAYS REPLACE GASKETSSTEP-BY-STEP FUEL PUMP REASSEMBLY
After reassembling check valve in fuel pump body, using the following procedure will help insure proper reassembly: 1Insert two inminimum length 14 bolts (not the fuel pump bolts) OR 14 dowels, through the opposite large holes (6mm bolt holes) in the chamber plate, as locating dowels, and turn plate upside down so that the inner side is facing up2Insert coil spring and cap in place3Place Boost Chamber GASKET over dowels (bolts) and lower onto Chamber Plate BE SURE that gasket directional alignment is correct and that "V-tabs" are aligned4Place Boost DIAPHRAGM over dowels, and lower to assembly51530