I have twin Yamaha V6 200AET's. Port is contrarotating L200AET @ 1999. Stbd is 200AET @ 2000. I bought the boat with engines 2nd-hand. I'm still learning. Previous owner assured me very little hours on either engine. But no real info. No indications Power Heads have any major work done on them & very little corrosion. I live in Abu Dhabi where we have very high humidity & temps during Summer. Like US Southern States.<br /><br />We were running smoothly @ 3200RPM when the Stbd Engine started to sound different. I heard the alarm from the Steering Console & then noticed the RPM's of the Stbd Engine start to climb with (I think)a loss of speed. I closed the throttles immediately. Stbd Engine on idle & alarm continuing to sound but the engine appeared to be running OK. Possibly more smoke from the upper exhaust above water level below Powerhead.<br /><br />We headed for home on Port Engine OK.<br /><br />I attempted to restart the Stbd Engine a couple of times. To begin with the alarm continued to sound when restarted but there was thrust but I did not push my luck & shut her down.<br /><br />On one occasion the alarm did not sound. Engine seemd fine & we started motoring on both engines again. After about 60 seconds the same thing was repeated. ie alarm sounded with an associated increase in RPM from Stbd engine & a loss of thrust.<br /><br />Reached home on Port Engine.<br /><br />Started Stbd engine in neutral on my mooring. She would not stay at tick-over but the RPM's surged up to @ 4,000RPM without my touching the throttle.<br /><br />Called-out our resident Mechanic. Went for a spin in the boat and .......the Stbd engine behaved perfectly!<br /><br />I've been out today....Stbd Engine has behaved perfectly again.<br /><br />Now, even though Stbd Engine is now behaving herself I'm very reluctant to venture far until I can sort-out what happened.<br /><br />I refueled 20mins prior to the Stbd engine misbehaving.<br /><br />Grateful for any suggestions.
