65 HP Johnson Troubles

[Cosworth]

Running at full throttle for few minutes and the motor just shuts down and won't restart for couple minutes.
I figure some kind of vapour lock appears at full throttle, as I can run it at 75%+ all day no problems.

Any ideas?
Thanx

 

[jtexas]

Re: 65 HP Johnson Troubles

What year motor is it?

Have you tested the overtemp alarm lately?
When was the water pump impeller last changed? Thermostat?