i have a 2000 Yamaha 40 hp (f40esry) with the same problem. It sat for 1 year. i replaced the fuel tank, both fuel filters,removed the carbs and cleaned them and replaced the plugs. It idles fine but when i i give it the gas to go on and take off it dies, when it does die it will started right back up and idle perfect. It acts like to me it is starving for fuel under a load,fuel pump maybe?? Any help would please?
