A bad fuel pump lobe on the cam would be possible, but about as rare as a hens tooth. If you attach the line from tank to pump and attach the line from pump to carburetor...with filter removed, and then crank the engine, what comes out?
If there is junk in the tank and a flexible hose on the tank discharge, It might be old and funky and collapsing under suction.
Be sure you get fuel all the way to the carb inlet before you do anything else. If it makes it that far, the needle and seat is capable of shutting off the flow if the float is hung up or there is an dead earwig wedged in the needle/seat orifice.
