[papajam]

Sounds like something to do with the accel pump circuit. Try taking off the pump jet plugs and work the throttle by hand. Does fuel come out? If so, pull the pump jets and make sure that those tiny little .35mm holes are clear. If they are clear, I'd go up a step or two on the pump jets.
If fuel doesn't come out, then I'd suspect something with the pump piston or the inlet/discharge checkvalve(s).