Do you have to take the tank out to replace the fuel pump?

Although I have never personally removed the fuel tank from a 1999 Chevy Lumina, on most sedans you must first RELEASE THE FUEL PRESSURE FROM THE FUEL SYSTEM (follow standard safety precautions in doing so)*, hoist the vehicle on a lift, position a support under the tank, then undo the two fuel tank straps to free the tank. Once the tank is free, CAREFULLY maneuver the tank out of place, and disconnect the pressure line, return line, gauge lines, and vapor line from the top of the tank, before lowering the tank fully from the vehicle. It is also recommended that you siphon as much fuel out of the tank before proceeding to reduce the weight of the tank.

* A good way to relieve the fuel pressure in the system is to either remove the fuse for the fuel pump or disconnect the inertial switch in the trunk so that the fuel pump cannot engage. Once you have disabled the fuel pump, start the vehicle. Once it stalls and cannot be restarted, the pressure has been relieved from the fuel system. NOTE: You will need to cycle the ignition key several times after you have finished your work, in order to restore fuel system pressure, prior to being able to restart the vehicle.