I just bought a '91 3hp gamefisher for my 10' boat. It runs perfectly while it's out of the water (it's air cooled) but will "bog down" and die when you put it in the water. It will idle okay , but once you start to increase the throttle it will bog down and shut off, it doesn't matter if it's hot or cold. Once it shuts off it'll start again with just one pull and go another 200 yds or so before it shuts off again. I opened everything up expecting to find a gummed up carb, but it was surprisingly clean. I couldn't find anything restricting flow of fuel or air. It's got plenty of compression and everything turns smoothly. This is one of the models that doesn't have a muffler. The exhaust it just piped down below the water and comes out a couple inches above the prop. My question is....i know it's designed to function that way, but could the backpressure put on the exhaust by the water be causing the problem? It has a few small holes drilled in the exhaust pipe above the water level to relieve some of the pressure....if this turns out to be the problem all i'd have to do is drill a few more hole and it should run fine. Hopefully some of you guys have some experience with these motors...i'm new here, but you guys seem to have quite a bit of knowledge about boats and motors.