I would test the pump before replacing it.
This could be done by:
Make sure there is fuel in the tank, regardless of what the fuel gauge says. (just add 5 gallons to be sure).
Remove the fuel hose from the carb, and put that hose in a bucket. Then spray a 3 second shot of starting fluid into the carb. Have someone start the engine, and as soon as it starts, spray a light stream of starting fluid directly into the carb. This will get it running and keep it running, which will run the fuel pump much faster than what the starter motor can do. After 10 seconds, if there is no fuel coming out of the hose into the buckety, then the fuel pump might be bad. Or it could be a leak in the fuel line between the pump and the tank.
Keep in mind that spraying starting fluid into the carb while its running requires that you keep your face away from the carb, have a fire extinguisher handy, and preferably do this outside - not in a garage. If it pops back through the carb, there will be a brief "whoosh" of fire, but it will be done and over with very quickly, and generally doesn't cause any problems or damage. Just rememebr, if you like your eyebrows, keep them away from the carb when using starting fluid.