Boat Dies out at High RPM

[79Merc Trouble]

My 1979 90 hp Merc trolls fine and accelerates well. Once at high RPM for approx 10 seconds the motor dies out and I idle the engine down and then reaccelerate it is fine for a few seconds then the same thing. I have been told that this could be a stator? What do you think?

 

[j_martin]

Re: Boat Dies out at High RPM

My 1979 90 hp Merc trolls fine and accelerates well. Once at high RPM for approx 10 seconds the motor dies out and I idle the engine down and then reaccelerate it is fine for a few seconds then the same thing. I have been told that this could be a stator? What do you think?

Sounds like it's starving for fuel. If you keep driving it like that, you will get a chance to try your hand at serious mechanical repair.

Check fuel delivery items. Air leak in fuel line to engine, plugged pickup tube in tank, plugged fuel filter, collapsing hose, tank vent, etc.

hope it helps
John

 

[kbazile]

Re: Boat Dies out at High RPM

in side your fuel pump the have what they call little bitty check valves one sucks and one releases i hade that same problem with mine a few years back and that was the problem what its doing it is starving for fuel but i dont thing your stator is bad if it would be anything electral it would fall back on your trigger

 

[79Merc Trouble]

Re: Boat Dies out at High RPM

We have had a mechanic check out all of the fueling issues as well having the carbs rebuilt. No problems in that department. The mechanic said that it was definitely an electrical issue, most likely the stator or possibly a CDI box? Both expensive fixes. Has anyone else experienced issues with their stator? If so, what was it doing?

 

[CharlieB]

Re: Boat Dies out at High RPM

Usually when the high speed windings of a stator begin to fail, the RPM is limited, the motor will run up to A 2000 to 2500 and just hang there.

Test the stator voltage as spelled out in the FREE troubleshooting Guide available for downoad at CDIelectronics.com

Your problem is common, as previously pointed out by j_martin.

If your fuel PUMP is weak it will not provide enough fuel for much more than an a few seconds of throttle.

Also air leaking INTO the fuel lines, a restriction anywhere from the tank dip tube to the carbs.

Three tests.
Running
Squeeze the primer bulb firm and keep doing it while opening the throttle.

Install a clear hose between the pump and carbs, watch the fuel looking for any air bubbles indicating air sucking into the lines before the pump.

Cranking
Pull the fuel line to the carbs and watch the stream, it should be a strong pulsed flow, @ least 15 GPH or more, any less the engine will starve for fuel, bog and die.