A fuel gauge tells the driver about the amount of fuel available in the car. Therefore, it is necessary for cars to have proper fuel gauges that tell accurate readings of available petrol. If a fuel gauge goes faulty, it won’t show accurate fuel tank readings and this could mean you getting stuck in the middle of nowhere with no fuel pump in sight. To avoid such dangerous circumstances, make sure your car does not have a faulty fuel gauge.
Causes of Fuel Gauge Malfunction
There is a definite problem with a car fuel gauge if it reads empty when the tank is full or it is stuck on full regardless of the amount of fuel in the car. If the fuel gauge fluctuates between empty and full that also indicates towards a fault. Following are the causes behind faulty fuel gauge issues.
Sending Unit Failure
The most common cause behind a faulty fuel gauge is sending unit failure. When your car is moving, the sending unit is in constant motion, rubbing the variable resistor constantly. As a result, over time, the contacts can wear off. This leads to an open circuit. The fuel gauge might take the voltage feedback from a dead sender as FULL or EMPTY, consequently pegging the gauge regardless of the actual level of fuel in the tank.
Circuit Issues
An issue with the circuit is another reason why your car fuel gauge is not working properly. Fuel gauge can stop its normal function with circuit problems. Depending on the location of the fault, the fuel sender may not have a source voltage, or the fuel gauge may not have a fuel sender voltage, or the base for either one may be interrupted. Loose connections and corrosion can also cause fuel gauge problems, since the fuel gauge is normally exposed to these elements.
Fuel Gauge Failure
The fuel gauge may not work accurately in one section if the internal circuit is faulty. This means the fuel gauge may only work in one section such as between half and full or between empty and half. In case of short circuits, the gauge may show readings to full or empty. On the other hand, an open circuit will lead the fuel gauge to get stuck EMPTY at all times and never move.
Instrument Cluster Failure
If there is a faulty fuel gauge because of an instrument cluster failure it will be a very expensive problem to fix. That said, instrument cluster failure is the least common. Modern clusters are fully-integrated circuits, they may not even feature replaceable bulbs. That said, if there is a fuel gauge malfunction because of an instrument cluster failure, you will need to replace the whole unit.
Identifying the Source Behind a Faulty Fuel Gauge
To avoid faulty fuel gauge problems, let’s identify the source of fuel gauge problems with some tests. However, before you start testing the fuel gauge to identify the source of the problem, keep an electrical wiring diagram (EWD), basic hand tools and a digital multimeter (DMM) handy.
Instrument Cluster Self-Test
An instrument cluster self-test feature is equipped with a number of latest cars and trucks. The self-test feature tests the computer-controlled instrument clusters. Read the owner’s manual to discover its procedure or search online (enter your car’s make, its model and type instrument cluster self-test in your search engine).
Usually, the self test procedure involves holding the odometer down as you start the car. This process is used to test the digital lights and readouts as well as swiping the panel gauges through their ranges. The fuel gauge should sweep smoothly from EMPTY to FULL throughout the test. Note that some self-test steps may stop the gauge at 1/4, 1/2, and 3/4, as well. However, if the fuel gauge reads incorrectly and is stuck at a point without moving – there is a problem.
Sending Unit Test
You should conduct this test when the tank is less than half. To start off, make sure the plug is clean, dry and free from corrosion. Ensure the pins are straight and connectors fully seated. You must also have a tool called a multimeter to test resistance. Finally, read the owner’s manual and determine the standard resistance for your car’s make and model.
After receiving the resistance results, compare them to the standard of your car. If the resistance is off by even a few ohms you will know that your sending unit is at fault. Generally, this happens when there is corrosion that keeps the float of the sending unit from working properly. Scrubbing it thoroughly with a fuel system car cleaner should sort out this issue.
Gauge Test
Another cause behind a faulty fuel gauge can be a simple voltage issue. Follow the steps in your repair manual and remove the instrument cluster in your car. Next, with the help of a multimeter test the gauge – it should come back as 12V. If the voltage looks good, your car probably has a faulty gauge that just needs a replacement.
Writing Test
If nothing went wrong when conducting the aforementioned tests, there might be a problem in the wiring and grounding. A common cause behind a faulty fuel gauge is wire corrosion, especially in cars exposed to water damage. Thoroughly inspect the wire running from the fuel tank to the gauge, clean or replace them if necessary.
If you still do not know the source behind your car’s fuel gauge malfunction, go to a professional auto workshop and have them identify and solve the problem.
Besides, if your car keeps asking for repairs frequently, it may be because of its age. Buying another car in this scenario can save you from multiple expenses. If you decide to go for another car, take a look at these used cars for sale in the UAE and buy a car of your choice.
Stay tuned to UAE’s top auto blog for more on car DIY solutions, car repair tips and much more.
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