To replace a malfunctioning fuel pump in your Hyundai Terracan, start by relieving fuel system pressure by disconnecting the fuel pump fuse or relay and cranking the engine. Disconnect the fuel lines and electrical connectors from the old fuel pump. Remove the retaining ring or bolts securing the pump and pull it out. Install the new fuel pump, reconnect the lines and connectors, and ensure all connections are secure. Refer to your Hyundai Terracan automotive repair manual for detailed instructions and precautions.