power loss

[Pepe]

I have a 2002 2 stroke 5hp yamaha. At about 3/4 throttle the engine bogs and will not rev. I have replaced the carburetor, all coils, except the ignition coil, CDI, timing key and filter. Nothing has helped. Sure would like a suggestion.

[Pepe]

Thanks for the reply Just in Time. As far as I know, the timing is flywheel-keyed and not adjustable

[jb123]

if your motor uses a fuel disconnect, either delete or replace as an airleak would cause similar problems under higher demand.

[Pepe]

Thank you Jb123. With a similar thought, I replaced the fuel line yesterday with no results. Is it possible to replace the hookup on the motor itself?

[Pepe]

JB123, the fuel hookup on the motor itself appears to be intact with no cracks or breaks. Also the valve appears to be functioning properly allowing fuel inlet flow and no backflow.

[Pepe]

Squeezing the fuel prime bulb at any speed does not affect engine performance.

[Baby Blue]

I had a similar problem on 10HP evinrude. Turned out to be the fuel pump (diaphram).
Just a thought.
BB

[Pepe]

Thanks Baby Blue. In the original carburetor, I cleaned and put a rebuild kit in twice. The kit contains the fuel pump. I have recently replaced the entire carburetor.