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why does my boat fuel gauge show full when on and when off shows actual level of fuel left
Working principle of fuel gauge
The reading of the pointer of the fuel gauge is detected by the oil level sensor in the oil tank, as shown in the figure below. The sensor has a float, which is attached to the liquid level, and the height of the float is kept in the same plane with the height of the remaining oil in the oil tank. Inside the sensor is a slide resistor, and the height of the float determines the resistance value of the slide resistor.
However, if the oil gauge shows no oil for a while and oil for a while, and the pointer of the oil gauge is inaccurate, what causes it? Let's analyze and study the causes and solutions.When the liquid level changes, the Shenyang value of the oil level sensor also changes. For example, when the liquid level is the lowest, the Shenyang value of the sliding vane Shenyang device is about 105-110 ohms
If there is no problem with the instrument panel, let's check whether the lower oil level sensor is damaged. The inspection method is very simple, that is, use the ohm gear of the multimeter to measure the positive current of the oil level sensor itself, which is at the lowest liquid level (the float position is at the daily position)
When set), the resistance value is about 100 ohms; At the highest point of liquid level, the resistance value is about a few ohms. It should be noted that the detection here is to detect the oil level sensor rather than the harness connector. In conclusion, if the oil gauge shows no oil for a while and oil for a while, the possible reasons are instrument panel fault, circuit fault and oil level sensor fault. It is necessary to detect relevant components and circuits.When the fuel tank is full of fuel, the resistance value of the variable resistor connected to one end of the buoy becomes smaller, the current of the entire circuit reaches the maximum value, and the fuel gauge pointer is at the highest position; when the fuel volume decreases, the resistance value of the variable resistor corresponds to Increases, the circuit current decreases, and the fuel gauge pointer also decreases. If the fuel tank is a regular geometric figure, such as a cuboid, a cylinder, etc., in any cross section of the fuel tank, the volume of oil at the same height is equal. In this case, the rise and fall of the float of the fuel tank are very linear, and the signal transmitted to the fuel gauge is also linear. At this time, the fuel gauge can truly reflect the remaining fuel quantity.
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