'06 Yamaha F50 4 stroke.
Starts and runs fine at low to mid rpm/throttle. In the video you can hear/see there is a problem when I reach about 2/3 throttle - the engine starts missing.
Motor was fogged and fuel stabilized for winterization in October. Spark plugs are fine. I have an inboard gas tank and above deck/external gas tank setup. I put fresh fuel in the external tank. October 2010 gas in the inboard tank, but I added stabil. Tried every combination of tanks - inboard tank only, external tank only (with brand new fuel hose), and both hooked up at same time. It's not water in the fuel or a problem with filters.
I am guessing it is a weak fuel pump? Anyone else seen this before? Thanks!