Re: Johnson aqua bouy
The exhaust goes up and out the mast, blowing straight up. The breathing air comes from under the top shroud. Ok, so it is possible that the engine's exhaust gasket could leak, putting exhaust under the shroud. I've never personally seen it happen, but if improperly serviced or (not) maintained, it could be possible.
The main thing I didn't care for is the air smells like a hot lawn mower. Which it is.