alarms

[Seumas]

I have 2 boats each with a pair of 140hp 2 stroke Yamaha's. I operate them in the arabain gulf. I have had a continuos problem with 1 engine on each boat. When under load, either with people or dive gear or pushing through heavy oncoming currents, the audio alarm sounds and the engine management system reduces the engine power. I have had them both in the Yamaha dealer workshop many times and even after spending a lot of money they are still unable to fix the problem. I have changed impellors and heat sensors without success.
Could this be thermostat related. Thanks Seumas

[99yam40]

yes could be thermostats causing overheat
Also make sure the oil level in the tanks on the motors are in the normal range when alarm is going off. Could be the filter at remote tank is restricting flow and will not let enough oil to flow to keep motor tank full in all conditions