A: It sounds as though your fuel sending unit has gone bad or the ground wire has lost continuity. The ALLDATA information system describes the testing procedures for the tank sending unit, that is if you are using a General Motors scanner. Basically, all it does is assimilate the signal sent to the computer by the sending unit. Giving the computer a certain predetermined voltage will make the gas gauge read at a different position. The diagnostics should not cost that much, however, if you need a new sending unit, you could expect to spend more than $600 installed.
Car Care Tip: Studded snow tires must be off the car by April 30, according to state law.
Larry Rubenstein is a master technician who owns a North Shore service station. His column appears every Saturday. Write to Larry at The Salem News, c/o Auto Scanner, 32 Dunham Road, Beverly, MA 01915, or send an email to email@example.com.