Don't know if your year is any different from my '90 740, but my gas gauge has been sticky for years, a common ailment. As I understand, the problem is usually up front, with bad contacts at the board. I know I should get under there and take a look, but I've put it off. One knuckle-rap to the left of the inst. panel cover invariably brings the needle right back up, where it stays as long as the engine's on. Happens every third or fourth time I drive.