I recently purchased a boat with a 90 Yamaha 2 stroke. Took it in for 3 yr service to get water pump changed etc. and the engine checked out good. When I took it out a few minutes after launching and still at idle speed the buzzer went off for about a minute then shut off never to return on that trip. The engine ran fine. It appeared maybe the Thermostat was stuck shut, who knows?
Recently took it out for the 2nd time. Ran great all day, no issues. Moved from spot to spot all day. When I start to head back I crank it up and move at idle out of the creek and the warning buzzer goes off again and stops after a minute or so. The boat performs fine at this point on the way back to the launch.
I have done some research on it and am confused at why it happens so infrequently and for such a short period of time? Oil level is good & the stream out of the engine also looks find. Any thoughts on the appropriate fix or where to look would be appreciated.