Fuel Starvation once running??

[2many280zzz]

Just converted from FI to carbs on a late '75 280. It runs fantastic until the float runs out of fuel. Pull the coil, crank starter, fill the bowl, plug in coil, repeat. Checked fuel flow when the car is actually running and there is NOTHING. Switched to a low pressure fuel pump that flows nicely but only when the ignition switch is cranking the starter. Apparently I've missed something in this conversion that is critical for telling the fuel pump to continue running when the engine is on, not just turning over prior to start. Any help is hugely appreciated.

Thanks a million!