Have you ever been frustrated with your fuel gauge? Have you ever wondered how such a simple device manages to consistently misrepresent exactly how much gas is in your tank? Before you haul your car down to your Seattle auto body shop, take the time to get to know your gauge. It isn’t broken, it’s simply experiencing the same limitations that plague all fuel gauges.
If you could open up your gas tank and look inside, you’d find something that resembles the floater in your toilet tank. This is the device that is operating the needle on your fuel gauge. When your tank is full, the ball floats to the top and your dashboard needle points to “F”. When it’s empty, the ball drops to the floor and your needle points to “E”.
The problem with this system is that the floater logically needs to be bigger than the rod it’s attached to. It’s therefore bound to hit the ceiling of your tank before it’s full of gas, and bound to hit the floor before the gas entirely runs out. This is why your gauge might claim that your tank is full for a good fifty miles after your last fill-up, and why it points to “empty” long before you find yourself rolling to an untimely stop.