Mercury Mariner 25HP 4-Stroke Outboard Service Manual 1997, Page 106Get this manual
4Rotate plunger 90 to offset slots Fuel Pump Installation
1Secure fuel pump to cylinder head cover with bolts
aSlots Aligned$Iots Offset
2Connect fuel lines to pump and secure with slastraps55780
5Assemble diaphragm, seal, and cover, to pump body, secure with screws and nutsNOTE: Seal installs in one direction only