You may already know this, but the Walbro has an integral pump with in/out valves (formed by gasket flaps) and it will ONLY pump gas when it receives pulses emanating from the crankcase through a tiny hole parallel to the inlet manifold. You cannot blow fuel into the carburetor like you can with a glow engine.
If the motor is dry then look for a blockage between the crankcase hole through the manifold to the carby..