2 Stroke 40 Alarm

Hello,

I take care of my elderly neighbor's boat. His 2-stroke 40 hp Yamaha's alarm is sounding. Pisser is working and oil reservoir is full.

Any thoughts on what else I should look for?

Thanks

I had this as an "overheat" alarm which would then slow engine to maximum of 1600 RPM.

Didn't seem or feel hot at all, but turned out that it actually was overheating.

I have a 1991 TLRP-90 and the Cylinder Head has two chambers, there was a pinhole leak from combustion chamber into the inner cooling chamber and after running for a while it would force the water out of this inner chamber.

You could hold a finger on the head for three seconds as cooling water was still flowing through that portion (outer chamber), but engine's temperature sensor is within the head against inner chamber and could sense the overheat condition.

Never noticed any steam from pisser as there was still plenty of cooler water flowing through, but had to replace the head anyway.

You could test the temperature sensor and see what temperature closes its contacts, but if it checks OK, then you've got to believe it. I found out that my 'finger test' was not enough and damaged my engine by ignoring it..

I have a 40hp yamaha 2 stroke and the alarm goes off every now and then when (I think) the wires coming out of the control box touch - I don't have them hooked up.