I've recently purchased a Johnson 40 VRO with electric start, trim & tilt, and remote steering. I've run the boat twice now. The first time I ran it was with a full tank of fuel that came with the boat. Yesterday I had to refuel. I added 10 ounces of oil (that also came with the boat) to 4 gallons of fuel (50:1). When I ran the boat it ran fine for a little while then at full throttle started revving down then right back up, then down, then up, etc. I suspect it has something to do with me filling the tank yesterday, since it ran fine for several hours before I added fuel.
I'm not very familiar with outboard motors but I'm suspecting one of two things (mostly because I don't know what else it would be). My suspicions are that when I filled the tank, some debris got stirred up and there is a restriction in the line or fuel filter?? Or, (after reading on here this evening) it could be a problem with the vent on the gas tank. I'll play with the gas tank next time I get a chance to take it out. Any other suggestions or possible issues? Am I on the right track?