You might check the clear plastic fuel lines in the engine compartment to look for signs of air bubbles.
You could also use the hand pump and see if by pumping, you notice any air bubbles going through the clear plastic fuel lines.

You might also consider the technique used for running Diesel Purge directly through an engine:
1. Pour a cup or so of fuel into a container such as a clean and empty mayonnaise jar.
2. Run a hose submerged in said jar to the intake port directly on the injection pump.
3. Place the fuel return hose into said jar.
4. Start the engine and see if it quits or continues to run.

This way, you would be completely bypassing filters and hosing to simply determine whether or not the fuel pump will take the fuel and the engine will burn the fuel and return what isn't used.