High Speed Overheat 200 Yamaha 2-stroke

[reelphisher]

Hello, here's what I've got - an all original 1994 200 Yamaha Outboard on a 20' Grady. I replaced the waterpump a couple months ago. The thermostats are in but gutted. Water indicator is peeing with very good pressure. Water temps 89 degrees located in SW Florida. Alarm goes off at 4300 RPMS followed by the engine sounding like hitting a rev-limiter on a car. I slow down to idle and leave the engine to run to cool itself off the but the alarm stays on. I shut off the engine, and start it back up immediatly and the alarm is off, go for another 10 minutes at 4300 rpms running normal and it comes back on with the same thing happening again. Any suggestions? Thanks, Jon

[boats.net]

If you are sure it is overheat alarm, check high pressure control valve, test temp sensors, install a complete water pump.

[gary miller]

0ver heat of 2000 pro v 150

have replaced complete water pump asy. new thermostats.removed heads ,cleaned all scale from interior water passages.removed and cleaned high preasure valve assy. can run approx 10 to 15 minutes before engine will shut down to half power with heat buzzer blaring.engine defiantly hot. this symptom existed before i started the repair process. i have a pressure gauge which indicates 20 to 13 lbs @2200 to4300 rpm. none of the parts appeared to be faulty or over scalded . what am i missing?

[99yam40]

How do you know it is a over heat alarm? Have you checked to be sure?
Have you tested the temperature switches or sensors to make sure they are doing there thing at the proper temp?
Have you ran with cowling off to see oil level when alarm goes off?
I have heard of the oil level not being able to keep up with high speed running caused by a partialy clogged remote tank filter bringing in a alarm but run fine at lower rpm