Jim Grant's Tech Tips
Pontiac Grand Am, Faulty Fuel Gauge
Q: I have a '99 Pontiac
Grand Am GT. The problem is when after filling the fuel tank the fuel
gauge needle will swing from full to empty with the yellow warning light
lights and chimes chiming. It was a very accurate gauge before this problem.
When a gallon was used, the gauge clicked off one mark on the gauge. I
checked for a damaged fuel filler cap gasket per manual. When on a long
trip, the gauge may not move for maybe 200 miles, then it swings to the
normal level per gas used. I suspect maybe a faulty ground wire or perhaps
the gas tank float is bad. ....Timsha
possible that the gas gauge sending unit is transmitting bad information.
The sending unit which is located in the gas tank is serviced/replaced
as an assembly and is a pricey unit. Proper diagnosis before replacement
is understandably important. If the sending unit has to the replaced you
can cut some labor costs by running the fuel level in the gas tank down.
The gas tank has to be drained before it can be safely removed and handled
from the vehicle. Having a near empty gas tank will quicken the repair.