yamaha engine slowed down

[Robby73]

I have a Yamaha 2002 115 2 stroke engine . I have had the boat out 5 times and this last time I was running at high speed and had been for about 20 minutes. The engine slowed down to just above idle with the throttle still forward for high speed. No horns were sounding . I crept back to the dock, shut the engine down and let it sit for a bit and tried restarting. It did restart but was not idling good. Any ideas and help would be appreciated.

 

[99yam40]

test the buzzer and gauges to make sure they work when low oil or high temp happens

 

[airshot]

Sounds like a sensor of some sort, but do a compression check to make sure the engine is sound before putting any money into it

 

[QBhoy]

Not much to these engines, in terms of sensors. They are fairly basic in that sense and yours is about the last they made of an engine that’s been about since the early 80’s.
If your alarm is working, it should have shown evidence of anything like and overheat or low oil, by and audible alarm. That’s about the only alarms these things have almost.
Assuming the above is not the case…the most likely cause of your issue is water in the fuel. That would be the sensible bet.
Hopefully not the case, but I am aware of one of these that suffered serious failure, as a result of water getting into the oil feed tank in the bilge of the boat. That didn’t end well….

 

[Scott Danforth]

Pour the contents of the fuel filter into a clear container and inspect it's contents for clean and pure fuel

Do a compression test

Check for overheating