1975 Johnson 4HP 4R75, 4W75 Outboards Service Manual, Page 23Get this manual
FUEL PUMP AND FILTER Before replacing fuel pump, remove and install new filter screen and gasketSee Figur 3-17Also remove the fuel line from the fuel tank and blow through all passages and lines with compressed air to be sure they are openThis may be th cause of inadequate fuel delivery, and if so, would eliminate unnecessary replacement of the fuel pumpIf this procedure does not correct the trouble fuel pump is probably malfunctioning and should be replaced
REMOVAL OF FUEL PUMP AND FILTER
Disconnect fuel lines from pump and filter assemblyaTo assure correct reassembly, identify fuel lines before disconnectingbTo remove fuel filter, remove screw and cover attaching filter to fuel pumpSee Figure -17 cTo remove fuel pump, remove two screws attaching pump to power head, and remove pump assemblySee Figure 3-17
CLEANING, INSPECTION, AND REPAIR
aThe fuel pump operating components are not serviced separatelyIf malfunction occurs, replace the complete pumpbClean all parts of the filter assembly and fuel connectors in solvent and blow dryDO NOT dry parts with cloth, as lint may stick to the parts and clog the passages or prevent the valves from seatingDissolve any gummy deposits with OMC Accessory Engine Cleaner (certain solvents will not dissolve these deposits)DNOTE