Originally Posted by ltgoshen
Yanmar's 2GM has provided almost 30 years of reliable operation, reports Andrew Norton
Released in the late 70s, the Yanmar 2GM was the forerunner of the 2GM20 and developed 13hp (based on 1.0hp equaling 746W) at 3300rpm with a maximum continuous rating of 11.8hp at 3200rpm. The RPM's my boat likes is 2200 rpm's and will not idle up much faster? It will not go to 3300? It has 30 years on the engine without an hour meter. I have no way of knowing how many hours it may have. It dont burn oil. That being said could it be the prop? or are the expections for this little prop and 11.8 HP engine set a little on the high side?
How about in neutral?
1. Test it with another tachometer.
2. If you are not getting enough RPM it's time to do some trouble shooting. Could be anything from the linkage/throttle to fuel to exhaust.
Do some research, make a list of possibilities and start checking them off.