Let's assume your engine has a good compression seal.

If you have the high-speed needle open about 2-1/2 turns, open the throttle wide, choke the intake, and turn the engine over and no fuel is drawn to the engine, you'll have to look to see if you have the fuel system plumbed correctly. Did you accidentally connect the fuel intake on the engine to the vent in the tank? Is there a blockage or kink somewhere in the fuel lines? Are all fuel lines (including the ones in the tank) solid with no holes or cracks?

Is there trash in the fuel system, needle valve, or carburetor? Is the idle needle turned so far lean that it's blocking fuel flow?

A lot of this sounds dead simple and maybe impossible to miss, but everything should be checked.

As a last resort, put the engine on a test stand and get everything properly set up so that you can see it's right. If the engine still has fuel draw problems, then the engine needs a good looking at.