How to Replace the Primer Bulb on an Outboard Motor With an Inboard Tank

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The primer bulb creates the initial flow of fuel between the inboard, built-in fuel tank and the carburetor, in low-pressure, carbureted outboard motors, or between the fuel tank and the vapor separation tank -- and the electric fuel pump -- on electronically fuel-injected motors. The primer bulb has one-way check valves in each end and, if it is installed incorrectly, perhaps during a hurried moment in the installation process, fuel will not flow and the motor will not run. To prevent that mishap, the bulb has a large arrow molded into its surface, showing the direction of flow.

Items you will need

  • Primer bulb replacement kit

Unsnap the clamps on the hose at each end of the bulb.

Pull the hose out of the check valves at each end of the bulb.

Open the new clamps and insert the fuel lines in them. Check the orientation of the bulb: An arrow is clearly visible on the squeeze bulb to indicate the direction of fuel flow. It should be pointed toward the engine.

Insert both of the fuel lines into the bulb so that the fuel line going to the fuel distribution appliance is inserted in the end of the bulb to which the arrow on the bulb points. The line from the tank should be on the end of the bulb where the base of the arrow is located.

Snap the clamps on the primer bulb. Squeeze the bulb until it is firm to the touch and full of fuel. Visually inspect the bulb for leaks.


  • The new clamps for the bulb come with the replacement kit.
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