Did you make sure that the passage that lets the crankcase pulses get to the carb pump are open and clear?
There is a passage to allow for the crankcase pulses to reach the pump diaphragm so it will move back and forth and pump. If that passage is blocked (eg putting the carb on the other way) then it won't pump. Some engines used a fitting and a short length of tubing to route the pulses to the engine too.