Just my $.02:
Mechanical pumps don't pump much at all if they get dry. (From just sitting for a while). Not even enough to draw fuel from the tank. Try to prime the pump, squirt fuel through the inlet or outlet to get some fuel in the pump diaphgram. Or you can open the fuel fill cap and try to shoot compressed air in there; cover the opening with your hand and shoot air in between your fingers. You don't need much pressure, very little is required to get the fuel flowing out towards the pump. Alternatively, you can try to suck fuel out from the hose coming to the pump. You may have a blockage somewhere too.
