Could be a plugged fuel filter, or perhaps a clogged jet/passage in the carburetor. Also it's unlikely that this is a 2 cyl engine at only 3 hp. If it's spitting and gives a kind of 'wheeze' when it dies I'd look into cleaning and rebuilding the carb.
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
1984 Fast/Nicholson 345 "FastForward"