25hp dies at full throttle

[perkdp]

Re: 25hp dies at full throttle

thanks for all the ideas. at this point, i have to wait for warmer weather. it is too cold to take it to the lake an try some things. and too much trouble & far to run back and forth.

 

[bktheking]

Re: 25hp dies at full throttle

This sounds like the motor is overheating. Are you sure it does not have SLOW mode? Is there a wire running to the head not far from the spark plug?

If you are out of ideas, take out the thermostat and try running it like that. You might be surprised at the results.

The motor is a 73, I don't think slow mode existed back then,

 

[perkdp]

Re: 25hp dies at full throttle

I installed a fuel pump kit which didn't fix the problem. But I think I learned something.
The fuel pump has a built in check valve to prevent fuel from going back to the tank on vaccum shift. This is not replaceable. My theory is: This check valve is leaking just enough so at high rpm it finally builds up pressure back to the tank and halts gas flow. (reason for hard bulb). When it stalls, the pressure is reduced, gas flows back to the bowl, all is good. I bypassed the pump with a "gravity flow rig" (gas jug, fuel line, 1x2 and C-clamps) and she seems to run fine. (couldn't test as well as I wanted due to rough water)

 

[perkdp]

Re: 25hp dies at full throttle

UPDATE:: Finally,, the weather got nice enough to get to the lake again (60 degrees and light breeze yesterday). I borrowed a fuel pump off a known good 6hp,, installed it on the 25,, ran WOT all over the lake. I have a new fuel pump on order from IBoats parts.