When driving a car, the driver is simply obliged to control all parameters. And this applies not only to the speed of movement. It is very important to know if the battery is charged, if there is sufficient oil pressure in the engine, if the temperature of the fluid in the cooling system is high. And there is no need to talk about the amount of gasoline in the tank, since this is one of the main parameters.
Fuel level sensors must meet fire safety requirements. They work in an explosive environment, so the slightest spark can cause a fire. In cars, float fuel level sensors are widely used. They are easy to manufacture and operate, relatively cheap, and have a relatively small measurement error.
Float level sensors
There are two main designs of float fuel level sensors:
- lever type;
- tubular type.
And the principle of their work is the same. The first level sensors use a resistor connected to a circuit with an indicator of the amount of fuel in the tank. A resistor is a plate with a nichrome wire wound on it. On the lever at one end there is a float, and at the other there is a slider, the output of which is connected to the level indicator circuit.
The fuel level indicator itself in the tank is a voltmeter or ammeter. Depends on what parameter is being monitored. The same operation scheme is exactly the same for tubular level sensors. The basis of the structure is a cylindrical pipe, inside which a float is located. It closes the turns of the wire wound on the inside of the pipe. The accuracy of such sensors is quite high, since there are practically no oscillations of the float when moving on an uneven surface.
In some designs, reed switches are sometimes used. The float is located around the tube, and there is a magnetic strip on it that acts on the reed switches. The reed switches are located in the tube body. The more reed switches there are, the higher the accuracy of this type of level sensor. Most likely, it is for this reason that sensors have not been widely used. Their production is too expensive.
Installing the fuel level sensor
On vehicles with injection engines, the fuel level sensor is combined into one unit with the fuel pump. This makes sense as it saves a lot of space, and there is no need to make separate holes in the tank for each node. On cars with a carburetor power system, the level sensor is installed in a special hole in the tank.
Using the example of a car with an injection engine, it is best to consider the process of installing a level sensor. After all, carburetors are not used in the manufacture of cars, because they are outdated for a long time. On most cars, the tank is located under the rear seat. Therefore, the lower part of the seat must be raised. Approximately in the center is the viewing window, covered with upholstery.
Removing the cover from the sight glass reveals the top of the tank and fuel pump with level gauge. Remove the entire assembly and disconnect the level sensor from the pump. Put a new one in its place, just make sure that all the wires going to it are correctly connected. It remains only to assemble the entire unit and, turning on the ignition, control the operation of the sensor. Calibration is not required when replacing a sensor with the same model.
