did you remove the line from the carb and from the pipe and blow in the one from the pipe and make sure fuel was coming out of the one that goes to the car? maybe something is blocked or the cap of the tank is not sealing so no pressure is building up in the tank, i had this happen to me today. there may be a hole in a fuel line. if all of this is good, does it start or try to start if you put a couple of drops of fuel in the carb?