Der!

Yes its called siphoning, whereby you use the atmospheric pressure to do the work, i.e. push the fuel towards the carb.
The venturi effect in the neck of the carb is simply to create a lowering of pressure within the carb at that point thereby inducing a greater flow of air at the venturi and inducing fuel flow.
If you don't believe me, seal the fuel tank and see how much fuel you get at the carb. I can tell you now that you will get Zilch fuel and risk pulling a vacuum in the fuel tank. A partial vacuum in the fuel tank could cause it to implode.

regards.

Chadz [8D]