2006 2.5 hp Yamaha not running at high RPM

[Erin]

I would like to share a problem with my little Yamaha 2.5.

Without any choke, I get an immediate start and low speed seems fine. When I throttle up, kicking into the high speed range, the RPMs just don't kick in. It appears to be running very rich, and leaves a black soot residue.

In addition, when I close the fuel shut off, reducing the fuel in the mix, the RPMs creep up and then really escalate before stalling.

I have put in a carbi kit including jets. It was thoroughly cleaned and blown out.

I read somewhere that the float needs to be set. Does anyone know about this? Or does anyone have an idea what I am doing wrong?

One last item, I have already tested adjusting the factory set air mix, through the full range and then back to the original setting.

 

[robert graham]

Re: 2006 2.5 hp Yamaha not running at high RPM

Check that fuel pump diaphragm for a rip/tear causing very rich mixture....Easy/cheap replacement/repair....

 

[Erin]

Re: 2006 2.5 hp Yamaha not running at high RPM

Thanks Robert.

I might be incorrect, but I think this model Is only gravity fed. I should have shared a little more information.

This is a a Yamaha four stroke model F2.5MSH, the serial being 69M S 1036792 J.

I included the serial as I believe some of the parts are significant.

Not sure if any of this helps....