I own 2002 yamah HPDI 200hp (xztra) with 150 hrs. It had been running great until sunday when after a whole day water sking and towing an inflatable raft, it lost half of its rpm range (and power). I had never run the engine this way, since this is the first time pulling skis, etc., so there was a lot of sudden acceleration and decelerations. I am wondering if the plulgs got fouled, or is it something more serious. Plugs were changed 1 year ago at 75hrs. I keep the boat on the water and I would like to solve this problem before the long weekend ahead. When the engine lost power it happened after a long time of running it hard and then turning the engine off without too much cooling off period. Then we sat at the beach for a couple of hours before we headed to port. That's when after turning the engine on, I noticed right away that it was running a litttle rough, and upon accelerating the rpm's would not climb above 2600 (properly trimmed out of course). My dealer does not have an opening for service till next month so I am going to change the plugs myself and see. Anything I should look out for? Indexing needed on this engine? I bought the plugs yesterday and will replace today or tomorrow. Any comments appreciated Thanks
