I have a micro pump that draws 600ma under load and 300ma with no load. It's installed on my motorbike to transfer the fuel from the reserve tank back into the main tank. it will run for about 1 min. To avoid running the pump dry, I would like to know, if any of you wizards out there can come up with a simple circuit that will sense the drop in current when the tank is empty and turn the pump off, via a relay. The pump has a brushless motor.