How do you change a fuel pump in a 2006 Buick lacrosse?

To change the fuel pump in a 2006 Buick Lacrosse, start by disconnecting the negative battery terminal and relieving the fuel system pressure. Remove the rear seat cushion to access the fuel pump access panel, then disconnect the electrical connector and fuel lines from the pump. Unscrew the retaining ring and carefully lift the fuel pump assembly from the tank. Install the new pump, reconnect everything, and ensure there are no leaks before starting the vehicle.