Fuel pumps work better pushing fuel rather than pulling (sucking) fuel. I don't know what vacuum readings they should be capable of. (This is talking about a mechanical fuel pump-without vacuum for the old vacuum windshield wipers)
Also fuel pumps are better at pushing liquid than air. When you get a "vapor lock" you need to let the fuel cool down and return to a liquid state before much will happen.
Just my thoughts
Adam
