Where is the door door to get to the fuel pump in the trunk of a Chevrolet Cavalier?

no you have to remove the gas tank.YOU HAVE TO DROP FUEL TANK TO GET TO THE FUEL PUMP.THE FUEL TANK MUST BE REMOVED, ONLY A FEW CARS HAVE AN ACCESS PANEL AND MOST OF THOSE ARE FORIEGN MODELS.

The car remote will lock and unlock all doors except drivers door in car?

Then you have a defective driver door lock actuator motor, to change this u must remove the door panel, drill out the rivet and remove the old motor and pop rivet the new one in place, this requires a special jumbo size river gun and a rivet head cutting tool.