Gauge Never Reads Empty or Reads Full at All Times with Ignition "ON"

Check for disconnected or loose tank unit feed wire at tank unit. Connect tester (J-22344 or equivalent) to tank unit feed wire and observe dash unit. If dash unit reads okay, check ground wire from tank unit to trunk floor pan for continuity. If no improvement, check cluster fuse or proper connections at dash unit and printed circuits. Check trunk harness to flat wire. Finally, remove dash unit and check.