Is your tank behind the seat? If so, you may have an air leak at the fitting at the top of the tank. It will suck air and prevent good/any fuel flow.
After you pulled gas with the vacuum pump, did the gas continue to flow on its own? If not, recheck the fitting at the top of the tank. Once you start the flow with the vacuum pump, gas should flow continuously via siphon action. A leak in that fitting will break the siphon.
Carl
