You're missing something. Disconnect the pressure tap on the muffler. Use a fuel bulb or something and see if you can push fuel into the carb. If the fuel's getting to the carb then there is probably a problem with the carb. Disassemble it and clean it. You may have some debris or residue clogging up the spray bar.

I just thought of something else... You didn't connect the fuel line to the overflow and the pressure tap to the clunk did you?