That black and green should be behind your radio and is probably not a complete circuit. You will have to complete the circuit so pump will come on with ignition.

You'll get voltage drops using the factory harness without a relay, so much you can actually hear the pump speed up and slow down when the indicators come on/off. Ask me how I know, ! Lower voltage means more current draw which may shorten the life of the pump. It'll also alter the flow rate.