What Causes Inaccurate Fuel Gauge Readings When Refueling Without Turning Off the Engine?
2 Answers
If the fuel gauge of a new car suddenly drops to zero, it indicates a sensor issue, and you can directly request a replacement from the 4S store. For older cars, timely cleaning is necessary. Fuel Level Sensor Damage: Since gasoline contains many impurities, and the fuel level sensor is constantly immersed in it, over time it becomes contaminated, directly affecting the accuracy of the readings. If the fuel gauge suddenly rises, this is mainly due to the linkage between the fuel level sensor and the float getting stuck, preventing the float from moving up and down normally. As a result, the sensor does not register changes, causing the fuel gauge needle to remain fixed at a certain position. Fuel Pump Design: For many car models, the fuel gauge drops relatively slowly in the first half but accelerates after passing the middle mark. This is primarily related to the design of the fuel pump used to measure fuel levels, which cannot uniformly reflect changes in gasoline consumption. Achieving absolute uniform changes is difficult and cannot be easily altered through repairs or part replacements.
Once I forgot to turn off the engine while refueling. The fuel gauge showed half a tank left, but the pump stopped, indicating it was full. I asked a professional mechanic friend, and he explained that with the engine running, the fuel pump is still operating, causing fuel to circulate in the tank. This makes it difficult for the float or sensor to measure the fuel level accurately. Engine vibrations and fuel sloshing can lead to inaccurate readings, and sometimes air bubbles can further affect precision. Additionally, this practice is dangerous, as the engine could produce sparks, potentially causing a fire. Gas station attendants often remind drivers to turn off the engine. The solution is to always turn off the engine when refueling, allowing the system to stabilize before taking a reading. If the fuel gauge frequently shows incorrect levels, the sensor might be faulty or there could be wiring issues, requiring inspection and part replacement. In short, safety comes first—develop the habit of turning off the engine to avoid risks.
