I have fixed several of thease machines. The electric pump might be to much fuel. I use the briggs&stratton vaccum pumps, they just pump when the engine is cranking.
Take a dremel to and cut a slot across the screws in the diaphragm cover then remove the screws with a straight screw driver.
Set the petcock to pri, this lets fuel flow all the time not just when the engine is cranking.
This machine needs to have a 135 main jet, and the needle clip needs to be in the 3rd notch down from the top, the fuel screw should be at base setting two turns out from seated.