2 thoughts.
1st, it's really easy to get the gaskets and diaphragms reversed/assembled out of order when reassembling these carbs. When that happens (either side), the fuel pump won't pump fuel. Refer to diagrams for both sides, as they are different!

2nd, many (most!) carb gaskets have a hole in them to allow crankcase pulses to pass to the carb. If the gasket is reassembled in a manner where that passage is blocked, same result. The fuel pump will not pump fuel.