I have had the carby off the tank numerous times and have cleaned the fuel tank out with clean fuel and blown it clean with air. I have had the suction tube off the carby and it is clean and also the other pick up that has gauze on it is clean as well. Could the metal balls that are in the carb have anything to do with it? If so can they be removed at all? As 1 or 2 of them are pushed in a fair way.
Josh