Yamaha 40hp CV 2 stroke. Approx 2008 build. Reasons for alarm sounding.

G'day all, I recently purchased a 2nd hand boat with a Yamaha 40hp CV 2 stroke. It didn't come with the manual for the engine.

I tried trolling on the weekend for the first time. I know 2 strokes don't like to idle for too long - without causing some issues with oil build up in the cylinders.

After about 10 mins in idle (and in Fwd gear) an alarm started from the Fwd controls. I turned off the ignition. For about 6-7 mins the alarm continued when I powered up the ignition and the engine would not fire up.

Eventually the alarm stopped and the engine re started without any issues.

I read another forum on this matter stating to "look at the gauges to identify the problem". I don't have any gauges.

Is anyone able to list the "problems" that will trigger this alarm. (and any other 40hp CV owners out there have you also had a problem with idling whilst in gear.

Many Thanks, Dave in Melbourne, Australia

First place to start is your waterpump just to make sure it is ok. Overheating at idle is consistent with a worn impeller. Also that motor normally should idle around 900 in gear. Too slow may not pump enough water. Your water is already almost overheated anyway!

Thanks PBRMAN. I would suggest you are right with the water pump. The engine is 4 years old and no replacement pump since new. Boat mainly been used in fresh water and possibly picked up some muddy water and worn the impeller a little. I would rather troll on an electric motor anyway... this will encourage me to get an electric. Many Thanks, David