1998 yamaha 90 hp, temp. alarm!?

Question

changed the impeller, thermostat, and the heat sensor switch in the block. motor runs and sounds good! half throttle it will run all day, @ 3200-3800 rpms alarm sounds and shuts motor down, block is cool to the touch when alarm is sounding, plenty of water coming out of the discharge at thr rear of the motor, and is cool as well. electrical? anyone with some info will be greatly appriciated!

Answer 1

part of the block is blocked

Answer 2

I had same problem.  The hose that runs from the water pump up to the top of the motor was partially stopped up.  It would let me run 3/4 throttle all day, after that alaram would go off.

Cleaned the hose out and it has run fine ever since.