Did you ask the AX glow fellow if he was using a three or a two line or if he had any opinion about this thread? If not what does that have to do with this thread?
It does not matter which end the pump is on. If you doubt that put a 5 ft line on the carb and try to pump it. It will not pump because the pump will not lift it.
The pump creates a vacuum and air ambient air pressure pushes the fuel up the line. The pump does not suck it up. Any change in the ambient air pressure will be reflected in the pump output.