Fuel level sensor VAZ 21099 injector

The fuel level sensor (FLS) has a round flange that is attached directly to the fuel tank. On the flange there is a sensor connection block with two terminals. A fuel intake pipe and a return pipe are welded to it. The sensor itself has a plastic housing mounted on a support plate. Inside the housing there is a rheostat with a winding of nichrome wire and a fixed contact for turning on the fuel reserve lamp. The contact is connected to the sensor block (terminal “W”). The rheostat has a slider mounted on a rotating axis and connected to a movable lever, at the end of which a sealed plastic float is installed. The lower end of the rheostat is connected to the sensor block.

The principle of operation of the fuel level sensor for VAZ 2108, 2109, 21099 cars

The float moves down or up when the fuel level in the gas tank drops or increases. At the same time, the slider connected to it moves along the rheostat winding, changing the resistance at the output of the rheostat from low to high and back. A drop and increase in resistance is reflected in the movement of the needle on the fuel level indicator in the instrument panel. The level in the tank is low, the float is lowered - resistance is 285-335 Ohms (the fuel level indicator arrow is at zero), the indicator arrow shows the tank half - resistance is 100-135 Ohms, the tank is full (the arrow is all the way to the right, the float is raised) - 7-25 Ohms .

In the lower position of the float, when the fuel level is at its lowest (4-7 l), the contacts on the slider and the contact of the fuel reserve lamp close. The lamp on the instrument panel lights up.

operation of the fuel level sensor (FLS) with a full tank: the float has floated up, the slider contact at the bottom of the rheostat (minimum resistance), the moving and fixed contacts of the fuel reserve indicator lamp are open (the lamp does not light up)

operation of the fuel level sensor when the fuel level in the fuel tank of a car drops: the float fell, the slider contact moved up the rheostat winding (maximum resistance), the moving and fixed contacts of the fuel reserve lamp closed (the lamp lit up)

Electrical diagram of connections of the fuel level sensor for VAZ 2108, 2109, 21099 cars

Electrical diagrams for connecting the fuel level sensor on VAZ 2108, 2109, 21099 cars with a “low” and “high” instrument panel are presented on the page “Connection diagram for the fuel level sensor on VAZ 2108, 2109, 21099 cars.” Applicability of the fuel level sensor on VAZ 2108, 2109, 21099 vehicles

On VAZ 2108, 2109, 21099 cars and their modifications, fuel level sensor 24.3827 and its variants are used. Its characteristics are as follows: voltage -12 V, rheostat impedance - 350 Ohm, float lever length - 115 mm, lever angle when the tank is empty - 27.5 degrees.

Fuel level sensor malfunctions

If the fuel level sensor fails, the fuel level indicator in the instrument panel either does not work at all or displays incorrect information. For more information about the malfunction of the fuel level sensor, see “The fuel level indicator in the instrument panel of VAZ 2108, 2109, 21099 does not work.”

Notes and additions

— A rheostat is an electrical device that allows you to regulate the current and voltage in an electrical circuit by changing the resistance of the electric current passing through its winding. The slider, being a movable contact, moving along the turns of the rheostat winding (conductor), changes the number of turns included in the circuit, thereby changing the length of the conductor and, accordingly, its resistance.

More articles on the fuel system of VAZ 2108, 2109, 21099 cars

If suddenly the fuel gauge needle drops down or behaves somewhat inappropriately, there is no need to worry too much. You can easily fix the problem yourself if it is a faulty sensor.

Appearance of the device

You should not ignore a breakdown of the fuel level sensor (FLS), because in the absence of information about the remaining amount of fuel, you run a high risk of not getting to the gas station, but stopping somewhere in the middle of nowhere.

Reasons for replacement

You will definitely have to replace the sensor if the car starts to produce the following:

The fuel level indicator needle “dances” or has fallen dead to the zero position;
The indicator is constantly on, indicating a critical fuel level, although you have just filled the tank full.

FLS diagram

FLS on high and low panels

The differences in the sensors on the injectors and carburetors are minimal. Also, the fuel level sensors on VAZ 2109 cars equipped with a low and high panel are slightly different.

The difference lies in the resistance indicators. These parameters must be known when checking the condition of the sensor resistor.

Panel type

Resistance readings

In this regard, when buying a new fuel level sensor, be sure to ask for a controller for a high or low panel, depending on what kind of car you have. It is also important to note that in the case of injection engines, the sensor is located inside the fuel pump, but it is based on the same operating principle as a carburetor one.

Sensor Features

The VAZ fuel level sensor in most models has virtually no different design features.
The FLS is a device with a float mounted in the gas tank of a car. Thanks to the position of the float, we get an idea of the amount of gasoline in stock - the lower it goes, the less the amount of fuel will be. The operating features of this device have minor differences depending on the type of engine. It doesn’t matter the carburetor or injector in your system - the principle of operation and location of the sensor remain the same. The measuring device, as mentioned earlier, is located in the tank, and can be accessed by tilting the rear passenger seat. This will come in handy if you need to check the sensor for functionality or replace it.

When it becomes necessary to check it:

The sensor does not show the gasoline level or is lying by several points. Sometimes the deviation from the truth is so great that it confuses the driver.
The device arrow is frozen in one position or does not move from the Zero mark.
Sometimes the opposite happens, when the arrow moves chaotically across the entire field.

Functionality check

Do not rush to throw out the old sensor and replace it with a new regulator. First you can try to check if it really doesn't work.

To check, you will have to extract the “suspect” in any case.

Inside the car, remove the lower part of the rear seat, remove the soundproofing material, if any. This will give you access to the inspection hatch in the floor of the car.
Using a Phillips screwdriver, unscrew the four mounting screws that hold the hatch in place. Take it off. Under the hatch you will find a sealing gasket made of rubber. In any case, even if the old sensor works again for the benefit of your car, this gasket should be replaced.
Disconnect the power supply block with wires from the sensor, and then unscrew the fastening nuts around the perimeter that hold the desired fuel level sensor on the tank body. Usually there are 6 of these nuts, and to dismantle them you will need an 8 socket socket or a regular wrench.
Under one of the nuts there is a ground wire attached to a stud. Remove the wiring and put it aside for now. He shouldn't interfere.
Carefully remove the sensor and do not forget to remove the rubber sealing gasket, which is located directly under the regulator. If there are signs of damage or defects on it, be sure to replace this component.
When the sensor is removed, visually check its current condition. If there are mechanical damages, there is no point in further trying to repair it or restore its functionality. Change it right away.
If there is no visual damage, check the condition of the float. It can be depressurized, that is, there is fuel inside it, cracks and various defects through which fuel has leaked are visible on the surface of the element. If all of this is present at the float, replace the entire sensor.
Be sure to blow out the fuel filter with compressed air. A useful event that definitely will not harm your fuel system. Especially if the quality of gasoline with which you fill your VAZ 2109 leaves much to be desired.
Check the condition of the resistor. To do this, you will need a multimeter in ohmmeter mode. Connect a measuring device to the sensor terminals and take readings. In the lowest position (empty tank), the resistance should be about 315-345 Ohms. If the tank is half full, the resistance will be 108-128 ohms. And when the tank is empty, the ohmmeter should show no more than 7 ohms. If the parameters differ from those specified, or there is no resistance at all, this indicates a malfunction of the controller. It must be replaced.

Checking status

Reassembly

It is necessary to follow the reverse principle of dismantling. But there are some nuances here.

Install the gas tank gasket onto the studs.
Replace the new or repaired old sensor.
Place the ground wire from the fuel level regulator onto one of the studs, after which you can tighten all six removed sensor mounting nuts.
Place the fuel outlet and supply hoses onto both tubes. You can then tighten the screws of the fuel hose clamps all the way.
Connect the power supply wire to the fuel level regulator and return the hatch cover to its place. Just don't forget about the gaskets. All of them are replaced in most cases with new ones. Even if the condition of the old ones is satisfactory.

Fuel level sensor (FLS) for VAZ 2108, 2109, 21099 cars

In the power supply system of the carburetor engine of VAZ 2108, 2109, 21099 cars, a fuel level sensor (FLS) is installed, designed to monitor the amount of gasoline in the fuel tank. It is located on the fuel intake in the vehicle's fuel tank. On the instrument panel there is a fuel level indicator and a fuel reserve lamp (indicator), connected by an electrical circuit to the fuel level sensor and transmitting information from it directly to the driver. The fuel level sensor (FLS) has a round flange that is attached directly to the fuel tank. On the flange there is a sensor connection block with two terminals. A fuel intake pipe and a return pipe are welded to it. The sensor itself has a plastic housing mounted on a support plate. Inside the housing there is a rheostat with a winding of nichrome wire and a fixed contact for turning on the fuel reserve lamp. The contact is connected to the sensor block (terminal “W”). The rheostat has a slider mounted on a rotating axis and connected to a movable lever, at the end of which a sealed plastic float is installed. The lower end of the rheostat is connected to the sensor block.

The principle of operation of the fuel level sensor for VAZ 2108, 2109, 21099 cars

Electrical diagram of connections of the fuel level sensor for VAZ 2108, 2109, 21099 cars

Electrical diagrams for connecting the fuel level sensor on VAZ 2108, 2109, 21099 cars with a “low” and “high” instrument panel are presented on the page “Connection diagram for the fuel level sensor on VAZ 2108, 2109, 21099 cars.” Applicability of the fuel level sensor on VAZ 2108, 2109, 21099 cars

The FLS is working properly. What to do?

Try the following activities.

The sensor connector has a pair of wires - pink and blue;
The pink one controls the arrow of the fuel level indicator in the tank, and the blue one is responsible for the critically low fuel level indicator;
Take any jumper at hand, that is, a piece of any wire, and then use the jumper to short the pink wire to ground, while turning on the ignition. At this moment the arrow should be in the full tank position;
Now, similarly, using a jumper, we connect the blue wire to ground. This should turn on a light that indicates on the dashboard that the fuel level inside the gas tank is low;
If, when the jumper is shorted to ground, the indicator or lamp does not work, this indicates that the indicator itself is “covered”, or there is a problem with the condition of the wiring.

There is absolutely nothing complicated about replacing the sensor. Dismantling work can be completed in 30-60 minutes with even a little experience. As for the FLS itself, it does not fail very often, but every owner of a VAZ 2109 and more should know about the features of its replacement.

If suddenly the fuel gauge needle drops down or behaves somewhat inappropriately, there is no need to worry too much. You can easily fix the problem yourself if it is a faulty sensor.

Appearance of the device

Fuel level sensors VAZ 2101-2107

The period of development of high technologies affected almost all areas of human activity, including the automotive industry. Carburetor engines are being replaced by so-called injection engines, the operation of which is controlled by various types of sensors. Modern cars with injection control systems contain a large number of them.

This article will focus on one of these sensors, namely the fuel level sensor (FLS). For car enthusiasts interested in this device, I will try to briefly outline the answers to questions such as:

Features of the FLS device.
Principle of operation.
Main signs of a malfunction.
Is it possible to repair the FLS?

The sensor is located directly in the car's gas tank. Let's look at what elements the FLS consists of on most Lada cars. The sensor is attached to the base of the fuel pump and consists of the following elements:

a reading device with a float connected to it;
connectors for power supply and connection to the fuel pump.

The idea of work is to correspond the level of gasoline in the tank to a certain sensor signal. By measuring the fuel level, the sensor transmits data to the car's dashboard. There are several options for such sensors, but their purpose is the same. The main signs of failure of the FLS are: the arrow on the instrument panel constantly moves; when the tank is fully filled, the arrow is in the zero position; Regardless of the fuel level, it does not move at all. Before replacing the sensor, you should check the fuse responsible for its operation and the wires for breaks.

The FLS is a fairly reliable device and lasts a long time. Of course, repairing this sensor is possible, but it is not a fact that after repair it will serve you for a long time. Given its difficult-to-reach location, I consider it advisable to replace the sensor with a new one so that it does not take up your time and effort in the future. The cost of a sensor for domestic cars currently fluctuates around 400-450 rubles.

In conclusion, I would like to warn car owners against the occurrence of unforeseen situations associated with the failure of any elements of the vehicle’s electrical equipment. When replacing various electrical devices, be it sensors or lighting bulbs, for complete safety, I advise you to disconnect the terminals from the car battery.

I hope after reading this article you have received a sufficient amount of information about how the fuel level sensor works and the principles of its operation.

Reasons for replacement

You will definitely have to replace the sensor if the car starts to produce the following:

The fuel level indicator needle “dances” or has fallen dead to the zero position;
The indicator is constantly on, indicating a critical fuel level, although you have just filled the tank full.

FLS diagram

FLS on high and low panels

The differences in the sensors on the injectors and carburetors are minimal. Also, the fuel level sensors on VAZ 2109 cars equipped with a low and high panel are slightly different.

The difference lies in the resistance indicators. These parameters must be known when checking the condition of the sensor resistor.

Panel type

Resistance readings

Operating principle of the fuel level sensor

Depending on the principle of operation of the sensors, the malfunctions that may occur with them will differ slightly. Let's look at the operating diagram of each type of fuel level sensor.

Float lever FLS

The operating principle of a float-type level sensor is based on the use of a rheostat. A lever is attached to its central part, at the end of which there is a float. Depending on the fuel level in the tank, the float will move, moving the rheostat lever accordingly along the contact path. During such movement, the resistance will change, which is recorded by the vehicle's electrical system. Accordingly, the arrow on the instrument panel will move in accordance with the indicated resistance on the rheostat. By the way, at a certain position of the float, and therefore the resistance value on the rheostat, a warning lamp on the dashboard will light up, indicating that there is little fuel left in the tank and refueling is necessary.

For clarity, let’s look at the operation of the fuel level sensor using the example of VAZ-2108/VAZ-2109, VAZ-21099 cars. Their design can use two sensors - for a high and low dashboard. They are structurally similar, but have different operating resistance. Specifically, for a high panel sensor, a resistance value between 238 and 262 ohms means the fuel tank is empty. With a resistance of 59...71 Ohms, the fuel gauge needle is approximately in the middle (accordingly, the tank is half full). If the resistance is within 17...23 Ohms, then this means that the car’s tank is completely filled.

As for the sensor for the low panel, the situation is similar. So, with a resistance of 285...335 Ohms, the arrow points to an empty tank. At 100...135 Ohms, the arrow will correspond to half, and at a value of 7...25 Ohms - at the end of the scale, pointing to a fully filled tank.

The specified resistances are important in the context of testing the sensor, since if it fails, the first thing to do is to check the internal resistance of the sensor using an electronic multimeter.

Please note that the indicated resistance values are relevant only for the listed VAZ models. For other machines, the corresponding values must be looked for additionally in the technical documentation (manual) attached to them. However, even these indicators can be used as a guide!

Tubular FLS

The design of the sensor is based on a housing with a guide post (actually a tube), at the other end of which there is a wire with a contact group (chip). The design also includes a float with slip rings located inside a hollow tube. The housing flange is secured using mounting bolts on the top wall of the fuel tank. By the way, this is a disadvantage of this type of sensor and imposes a limitation on its use. In particular, tubular type sensors can only be installed on tanks whose height is sufficiently large.

The operating algorithm of the tubular fuel level sensor is as follows:

On the tube that touches the bottom, in its lower part, there is a hole (or two) through which fuel enters inside.
The float located inside the tube has contact rings and when moving through the tube, as the fuel level in the tank changes, the resistance also changes. Resistance is measured using one or two contact wires located along the guide tube.
The movement of the float on the surface of the fuel naturally changes the value of electrical resistance on the contact wire when power is applied to it.
At the moment when the float is in the upper position (the tank is completely full), a small section of the contact wire is activated, and accordingly, the resistance value is minimal. At the moment when the tank is empty, the float is at the lower extreme point, respectively, the length of the signal wire is maximum, which also corresponds to the maximum electrical resistance.

The resistance of the fuel level sensor will differ for different cars, so when measuring you need to use technical documentation.

Electronic FLS

Electronic fuel level sensors are installed on cars that use high-quality gasoline and diesel fuel produced on a biological basis. This not only provides very accurate sensor readings, but also allows the actuator to “avoid touching” the fuel directly. However, the peculiarity of using such sensors is that it does not provide smooth monitoring of the fuel level (in small steps). The design of contactless FLS is based on an inactive magnetic sensor. The diagram of the fuel level sensor according to which it works is as follows:

The main part of the sensor is located in a sealed housing. Only the magnetic sensor (MAPPS) and its lever are in contact with the fuel.
The movement of the float with a magnet occurs along a sector defined by metal plates of different lengths. A signal corresponding to a certain fuel level in the tank is generated depending on the position of the magnet on a separate plate.

The fuel level indicator in this case is formed using a discrete method since the amplitude of the feedback signal will change from segment to segment that the magnet passes through. Depending on the model of a particular sensor, the signal amplitude and other technical information differ. The operating error of such a system does not exceed 0.5%...1%, but the cost is also significantly higher than a conventional contact system, so these FLS data are installed only on business and premium class cars.

Functionality check

Do not rush to throw out the old sensor and replace it with a new regulator. First you can try to check if it really doesn't work.

To check, you will have to extract the “suspect” in any case.

Inside the car, remove the lower part of the rear seat, remove the soundproofing material, if any. This will give you access to the inspection hatch in the floor of the car.
Using a Phillips screwdriver, unscrew the four mounting screws that hold the hatch in place. Take it off. Under the hatch you will find a sealing gasket made of rubber. In any case, even if the old sensor works again for the benefit of your car, this gasket should be replaced.
Disconnect the power supply block with wires from the sensor, and then unscrew the fastening nuts around the perimeter that hold the desired fuel level sensor on the tank body. Usually there are 6 of these nuts, and to dismantle them you will need an 8 socket socket or a regular wrench.
Under one of the nuts there is a ground wire attached to a stud. Remove the wiring and put it aside for now. He shouldn't interfere.
Carefully remove the sensor and do not forget to remove the rubber sealing gasket, which is located directly under the regulator. If there are signs of damage or defects on it, be sure to replace this component.
When the sensor is removed, visually check its current condition. If there are mechanical damages, there is no point in further trying to repair it or restore its functionality. Change it right away.
If there is no visual damage, check the condition of the float. It can be depressurized, that is, there is fuel inside it, cracks and various defects through which fuel has leaked are visible on the surface of the element. If all of this is present at the float, replace the entire sensor.
Be sure to blow out the fuel filter with compressed air. A useful event that definitely will not harm your fuel system. Especially if the quality of gasoline with which you fill your VAZ 2109 leaves much to be desired.
Check the condition of the resistor. To do this, you will need a multimeter in ohmmeter mode. Connect a measuring device to the sensor terminals and take readings. In the lowest position (empty tank), the resistance should be about 315-345 Ohms. If the tank is half full, the resistance will be 108-128 ohms. And when the tank is empty, the ohmmeter should show no more than 7 ohms. If the parameters differ from those specified, or there is no resistance at all, this indicates a malfunction of the controller. It must be replaced.

Replacing the fuel level sensor on a VAZ 2108, VAZ 2109, VAZ 21099

Welcome! Today we will discuss in detail the replacement of the fuel level sensor in the tank. The entire replacement process will be supported by pictures for your convenience, and at the very end of the article you can see a video that will describe in detail the replacement of the sensor and its configuration.

Note! The replacement process, as you have already seen from the title of this entry, will take place on cars of the “Samara” family!

Where is the fuel level sensor located? Its location is very simple, and all because it is located in the floor of the car body under the rear seat. But in order to get to it, you will first need to lift the rear seat cushion and after that, lifting up the noise-insulating material, you will be able to see the fuel level sensor installed in the floor of the car.

Note! In the photo above, the arrow indicates where this sensor is located, but as you can see in the photo, it is invisible, and all because the noise-insulating material is not bent back!

When do you need to change the fuel level sensor? It must be replaced with a new one if:

• Incorrect operation of the fuel level arrow, which is shown in the bottom photo. For example, if the sensor fails, the fuel level needle may begin to work incorrectly or may even stop showing the state of gasoline in the tank.

Location

If usually most repair work related to the engine and its system is carried out through the engine compartment, then in the case of the fuel level sensor everything is somewhat different.

The FLS is located under the rear seat. To access it, you need to remove the seat, bend back the soundproofing material, if any, and find the controller we need in the area above the fuel tank.

FLS location