Johnson, 40 hp outboard fuel issue?

[He Reigns]

My friends boat has a 2000, 3 cylinder Johnson 40 hp with a 20 jet pump. It has recently started bogging down when you hit the gas hard, to the point is dies. We ran a test today, when engine is off the fuel line pump bulb is hard and stays hard, when running it goes soft. If running at full throttle it will die unless you continuously pump the bulb, then he gets warning for low oil. I am thinking the fuel/oil pump needs a rebuild kit. Thoughts anyone?

 

[driz]

The first thing I would check is the fuel tanks vent. If air can't get in it will starve your fuel flow.

 

[Pappy]

By pumping the bulb you are essentially replacing the engine driven fuel pump. Either replace or repair the pump.
BTW - The primer bulb will NEVER remain firm while the engine is running. Once running, the primer bulb is on the SUCTION side of the pump.
There is no pressure inside the primer bulb unless it is being hand pumped.

 

[JL8Jeff]

Sounds like the fuel pump diaphragm needs to be replaced. I ran into that on my 99 Johnson 40 hp. The VRO pump went bad and I replaced it with a non VRO fuel pump (a lot cheaper) and then 5-6 years later the non VRO pump went bad. I think the rebuild kit was around $50-60.

 

[He Reigns]

Thank you for the help guys, we got it sorted out, the fuel tank was not venting.

 

[JL8Jeff]

Between fuel pump, fuel line, bulb, tank pickup, tank vent it can take some testing to figure these things out. One rule I have is to go upstream first! :lol: And bring a good anchor, rope and paddle.

 

[Pappy]

When the fuel tank is not venting the primer bulb normally goes flat as a pancake. If that is what was happening and you had mentioned that it would have helped.
Glad you got it repaired though. Good fishing to you!