The carb fan is useful after the vehicle is shut off. The heat sink from the engine causes the fuel to turn from liquid to vapor. Hence the term “vapor lock”. The fan (if equipt) turns on when the ignition is of. It is like a warm summer breeze that keeps the fuel from vaporizing. I am attempting to build three crappy vehicles into one and will utilize a carb fan in the final product. Your issues are not related to the carb fan but something else.