In order to deal with common fuel gauge problems, you have to understand first how this device works. Basically, an electric gas gauge is composed of two main parts.the gas task sender, which is attached to the fuel tank, and the dash gauge. Once you switch on the ignition and depending on the amount of fuel inside the tank, the amount of current that flows from the ignition switch to the dash gauge's operating coil increases or decreases. This will then dictate the movement of the needle. So technically, it's electrical resistance or friction from the tank sender that directs the flow of the electric current to either the dash gauge or the sender.
Now that you have an understanding of how this gauge works, here are some of the most common fuel gauge problems you might encounter and what you need to do to fix them:
There's poor ground at the tank sender.
A malfunctioning gauge is commonly caused by a tank sender with poor ground. Because poor ground basically means a loose connection within the gas gauge system, double-check all wires and connections. See if the links are tight and that there is no dirt buildup or corrosion along the wires. To remove dirt, simply wipe it off with a rag dipped in wire cleaner or greaser. If there's corrosion, try to put some grease on the rusty patches. If this doesn't work, replace the badly corroded parts.
No current reaches the gauge.
If the fuel gauge needle indicates that the tank is empty but is actually not, it means that the electric current from the battery isn't flowing to the gauge. To figure out the culprit, link a jumper wire between the dash gauge and the ignition switch. If the gauge is working properly, you need to replace the faulty wires between the switch and the gas gauge.
The gauge needle is unresponsive.
If the needle doesn't move when you turn the ignition switch on or off, it means either the tank sender or gauge is defective. With the use of a jumper wire, ground the terminal of the gas tank sender. If the gauge indicates an empty tank level, the sender is defective and needs replacement. But if the gauge needle doesn't move at all, you'll have to get a new fuel gauge.
Tank level indicated is lower or higher than it actually is.
If the tank level indicated by the gauge is inaccurate, check the wiring between the tank sender and the gauge for signs of damage. Also check if there's poor ground at the tank sender. If the wiring is faulty, replace it ASAP.
Fuel gauge is badly damaged.
If the actual gauge unit is damaged beyond repair (severely cracked or chipped glass, needle is broken, etc.), you need to get a replacement unit right away. Keep in mind that a faulty gas gauge can cause inaccurate fuel tank readings, which could then prevent you from stopping by the nearest gas station even though the tank is nearly empty.