My Atomic 4 has a mechanical
fuel pump, so I'm not the best reference. Have you tried putting a multitester on the leads to the
pump to check the voltage before and after the engine starts? It seems possible that there's a surge or a swag that it doesn't like. You might also consider running one or two temporary wires to the
fuel pump to verify that there isn't a short that kicks in when the vibration of the engine starts.