Question: Our car is a 1970 Plymouth Satellite four-door sedan with only 39,138 miles. In November, 1984, the gas gauge went out, and we had a new float installed. Eight months later, it went out again, and we had another new float put in. Just six months later it failed again. My question is: Why would the original float last 14 years and the new ones only last six months? At $90 per float, this can get rather expensive.--K.H.
Answer: It's unlikely that both the new floats are defective, so you have to look into the possibility that you have some kind of condition inside the gas tank that is attacking the new floats.
The gas gauges on almost all cars operate by receiving electrical signals from a gauge inside the gas tank. The gauge operates by a float that rises and falls with the gas level. The float is connected to a variable resistor that controls the electrical signal sent to the dashboard gauge.
Since the floats are made of brass, under no circumstances should they corrode in only a matter of months. The float unit's electrical components, however, could be attacked by contaminants that would cause corrosion and failure.