I posted a few months back about a fuel starvation issue in a 1993 Yamaha 225. Turns out the culprit was stuck check valves coming off both main and aux. gas tanks on a Grady White Explorer (one boat yard looked at the boat 5 times and didn't see this-a second boat yard noticed it immediately). We replaced them with straight barbs and the engine picked up about 8-9 knots. <br /><br />Now the engine usually runs well at >2800 but getting from 1000 to 2800, it coughs, surges, loses rpms, and sometimes chokes out. Occasionally it will only get up to ~1800 rpm with the throttle opened up but then suddenly surge up to 5000 and run well until I slow it down. Also, when running wide open, any cut back in the throttle slows it right down to idle. Fuel lines, manifolds were changed recently and filters etc. checked at the beginning of the season (July). I'm thinking it may be an issue with the carburators.
