Why Does the Fuel Needle on the Car Dashboard Swing Back and Forth?
3 Answers
The reason why the fuel needle on the car dashboard swings back and forth may be due to a malfunction in the fuel level sensor. It is recommended to visit a 4S shop for inspection and repair as soon as possible. Below is some information about the car dashboard: 1. The car dashboard is a device that reflects the working conditions of various vehicle systems. 2. Common indicators include the fuel indicator, washer fluid indicator, electronic throttle indicator, front and rear fog light indicators, and warning lights. Additional Information: 1. The car fuel level sensor can float on the surface of the fuel layer. Using the lever principle, the other end of the float is connected to a potentiometer. The amount of fuel determines the height of the float, and the potentiometer at the other end will reach different potentials based on the fuel level, which is then displayed on the dashboard. 2. The principle of the car fuel level sensor is based on a wire-wound resistor. The resistivity is determined by the material of the resistance wire, and the resistance value is determined by the material's resistivity and the number of coil turns.
Last time I drove my old Focus, I experienced erratic fuel gauge behavior. It turned out the float in the fuel tank was stuck. That metal float is connected to a resistor strip, which wears out over time. When the fuel sloshes around, the resistance fluctuates wildly, making the fuel needle dance around. This happens more easily in summer when fuel temperatures are high. Once while driving on winding mountain roads, the fuel gauge needle kept sweeping between 1/4 and 3/4, which scared me into refueling immediately. The mechanic said if it frequently gets stuck, the entire fuel pump assembly needs replacement - otherwise it might suddenly drop to zero someday, which would be embarrassing. Now I'm extra careful when refueling and find tracking mileage more reliable than trusting the fuel gauge.
The mechanic taught me that when the fuel gauge acts up, you should first check three things: whether the fuel tank float moves smoothly, if the sensor's resistance value is stable, and if the wiring connectors are corroded. My ten-year-old off-road vehicle had this issue after driving through muddy roads on a rainy day—the fuel gauge went crazy. Upon disassembly, we found the wiring harness connector soaked in muddy water. The mechanic sprayed it with rust remover and applied conductive paste to fix it. Now I know that poor grounding of the fuel pump wiring often causes this problem, leading to intermittent contact when driving over bumps. Last time, my neighbor's electric car had its subwoofer modified, and the power cable interfered with the fuel level signal, causing the needle to jump erratically. That reminded me to be cautious with electrical modifications.
