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When you change the fuel pump on a Yamaha outboard, you're making a straightforward swap, an old pump for a new one. The method for removing the fuel lines from the pump may vary according to the pump configuration or the engine's horsepower. After that, it's little more than "out with the old and in with the new," as two bolts are threaded into place and your motor is ready to go once more.
Items you will need
Scraper or razor blade
Plastic wire ties
Removing the Fuel Pump
Disconnect the cables from the battery. If you accidentally create a "dead ground" involving a hot wire or an electrical component, the resulting sparks may ignite the fuel vapors present while you're working on the fuel system.
Wrap a piece of duct tape around each line on the three hoses connected to the fuel pump. Write on the tape with an indelible pen where the hoses are connected: top, bottom, cover plate. Disconnect the fuel hoses from the pump. Cap the two fuel hoses with a strip of duct tape as you disconnect them from the pump. Remove from the pump cover the vacuum hose that runs the pump. The vacuum hose does not need to be capped with duct tape.
Remove the bolt next to the pump cover nipple and the bolt diagonally across from it, using a 1/4-inch socket. Remove the pump from the engine block. Remove any bits of the mounting gasket from the block with a razor blade, putty knife or other scraper.
Installing the Fuel Pump
Slip the two mounting bolts through the new pump, allowing you to fit the new gasket onto the bottom of the pump. The mounting bolts will hold the gasket in its proper alignment while you mount the new pump. Grab the pump and the gasket and set the pump in place on the engine block.
Thread the mounting bolts into the block and tighten them to 55 inch-pounds with a torque wrench. Reconnect the two fuel lines, using the tags as your guide, and reconnect the vacuum hose to the pump's cover. Wrap plastic wire ties around the lines to hold them in place on the pump.
Reinstall any parts you had to remove to gain access to the fuel pump, in the order in which you removed them. Reconnect the cables to the battery.
- "Yamaha/Mercury/Mariner 4-Stroke Outboards 1995-2004"; Seloc Marine; 2007
Will Charpentier is a writer who specializes in boating and maritime subjects. A retired ship captain, Charpentier holds a doctorate in applied ocean science and engineering. He is also a certified marine technician and the author of a popular text on writing local history.