Written by Lee Wyatt (last updated May 27, 2010)
Without doubt, one of the most vital parts in any vehicle is the fuel gauge. Unfortunately, this essential gauge does not always last for the life of the car or truck. You can spend a lot of money and have someone else fix the problem. Or, you can fix your own fuel gauge and save money for other important things, like gas.
Before blaming the problem entirely on the fuel gauge, check to see if the temperature gauge is working.
If it doesn't work, there are a couple of things that you need to check. The first would be the fuses. A blown fuse could cause a fuel gauge and a temperature gauge to misbehave. If the fuse is ok, then you want to check what is known as the voltage limiter. This is located in a different place for each vehicle, so be sure that you consult a good diagnostic book prior to doing any real electrical work in your vehicle. These publications typically have an electrical diagram which is going to be very helpful.
If the temperature gauge does work, then there are several other things that could be wrong. This list includes bad or corroded wiring, the sending unit, or that the gauge itself is bad. Each of these potential trouble sources can, and often are, the sole or collective cause of any fuel gauge malfunction. The easiest thing to check is the sending unit.
Take a normal multi-meter and test to see if the resistance is normal. Don't try to guess what your fuel tank level is. Prior to checking the sending unit, fill your tank to the top. Set the multi-meter to the 0-100 Ohms range and place the red probe of your meter to the center post of your sending unit. Check your reading; if it reads 9 to 10 Ohms, then you know you have a full tank. If the reading says between 96 and 98 Ohms, then the sending unit is out of whack and needs to be replaced because it is reading that you have an empty tank.
For a detailed "how-to," get a detailed diagnostic manual, since this is typically considered an easy repair. These diagnostic manuals will have detailed diagrams and instructions that are extremely helpful to any amateur car enthusiast, and even for the experienced car repair guru.
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