Abstract: A fuel transfer control apparatus in a motor vehicle for automatically shutting off the transfer of fuel from an auxiliary tank to a main tank once the main tank is full and has begun to overflow. The transfer control apparatus is readily installed and includes a chamber having an inlet opening for receiving fuel overflow from the main tank and an outlet opening for connecting the main tank to an outside source of fuel. The transfer control apparatus also includes a sensor for monitoring the level of fuel in the chamber and a switch activated by the sensor for automatically stopping the transfer of fuel.