You need to have good flow out of the fuel tank through the line to the pump. Remove the line at the pump and turn the valve on. Also the line after the pump to the carb as well must be open. Was there debris or water/ corrosion in the carb? Generators are classic for carb issues and especially water damage won't always clean out.

The carb looked pretty good when I had it apart. The fuel flow at the lines was poor and the valve grommet was damaged. I did assume a blockage, so I just replaced all the fuel lines and valve/grommet. I also checked inside the tank when I had it emptied and it looked good...also looked around from the underside when the valve was out and it looked clear as well. But to be honest, since then, I don't recall checking the flow from the valve so I'll do that.

Fuel pump? That just striked me odd since all portable gens with a top mounted fuel tank are gravity fed and dont require a fuel pump. If it does have one, you could possibly by pass it. A common blockage problem is the valve mounted under/into the fuel tank.

Also--check the breather hole in the gas cap! Might be plugged up, usually by a "Mud Dauber" wasp! They just love to lay their egg in those teeny holes, and when it hardens, there stays the gasoline in the tank, because it draws a vacuum, and won't let the fuel run out into the carburetor! This problem has given many a home owner the fits. And, in the spring and early summer, i get a few machines in for just that problem!

twostroke, its not uncommon to find a fuel pump on gensets with a overhead fuel tank. Some of these tanks are so large they can produce more gravity created fuel pressure then the float in the carb can hold back. The fuel pump is used more as a pressure regulator then as a pump.