From the owners manual:
Priming the Fuel System
If the motorcycle runs out of fuel, prime the fuel system before attempting to restart the
1. Fill the fuel tank.
2. Turn the ignition switch to the ON position.
3. Move the engine stop/run switch from the STOP position to the RUN position.
4. Allow the fuel pump to run until it stops (about 3 seconds).
5. Move the engine stop/run switch to the STOP position.
6. Wait 10 seconds to allow the engine control module to reset.
7. Repeat steps 3-6 four to five times.
Have you tried this?
'12 Vegas, 78 Bonneville, 69 BSA project.