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Fuel Gauge

Views: 0     Author: Amber     Publish Time: 2022-03-21      Origin: Site

1.What Is Fuel Gauge?

The fuel gauge is used to indicate the amount of fuel in the car's fuel tank. It can be a pointer or a digital display. The fuel gauge consists of a fuel level indicator with a regulator and a fuel level sensor. The function of the low fuel level alarm device is to light up the alarm immediately when the fuel quantity in the fuel tank is less than a certain value, so as to attract the driver's attention.

2.How Does Fuel Gauge Work?

The fuel sending unit is located in the gas tank to measure the fuel tank level. Some sending units are attached to the fuel pump assembly, while others are stand-alone units, but both are made up of the same three components: float, a metal rod/arm, and a variable resistor. These three components work together to measure the vehicle’s fuel level and relay the information to the gas gauge.

  • Float: The float, which is made of a buoyant composite or foam, floats on top of the fuel in the tank.

  • Metal rod or arm: The float is connected by a thin metal rod to a contact inside the variable resistor.

  • Variable resistor: A resistor is an electrical device that resists the flow of electricity, and a variable resistor has the ability to adjust the amount of resistance voltage encounters by sliding a contact (wiper) over a resistive element. The wiper is connected to the fuel gauge either directly by wire, or indirectly to an electronic device that communicates with the fuel gauge. In a fuel sending unit, the variable resistor receives power via a small coil from the vehicle’s battery, which is used as the baseline signal.

3.How A Fuel Sending Unit Measures Fuel Tank Levels?

The float in the fuel tank will move up or down according to the fuel level. The metal rod pivots in relation to the float, which causes the wiper inside the variable resistor to move as well. The wiper moves along a strip of resistive material connected to a ground on one end, and the strength of the electric current from the resistor is determined by the position of the wiper to the ground.

The wiper sends the electric current to the fuel gauge, which displays the fuel level accordingly on the vehicle dashboard.

Fuel sending units work differently depending on the manufacturer.

When the fuel tank is completely full, the wiper is either closest or furthest from the ground on the resistive material strip. Here is where there is either the least amount of resistance or full resistance respectively.

When a vehicle is almost out of fuel, the wiper again is either closest or furthest from the ground as float rests at the bottom of the metal rods travel. Depending on its specifications, the fuel gauge will show full or empty according to what resistance it reads as full or empty.

As the fuel level along with the float lower in the tank, the metal rod connected to the float either moves the wiper further or closer to the ground, which either restricts or increases the amount of electric current being sent to the fuel gauge. The fuel gauge display drops from full according to the resistance change.

4.How To Fix The Gauge?

A stuck fuel gauge on your car is not only annoying, it is also a hassle as you need to keep track of the number of miles you have driven since your last fill-up to prevent you from running out of fuel.

A fuel gauge functions using a series of electrical connections from the sending unit to the gauge cluster, and when one of these connections fails, so does your fuel gauge. The good news is, you can troubleshoot the problem yourself and avoid an expensive repair. Here’s how you can do it:

Step 1: Turn the ignition on and off a few times, and observe if the needle on the fuel gauge moves. If the needle does not move, it most likely means you have a blown fuse and it is due for replacement. The fuse box can either be found on the driver’s side dash or in the engine compartment. Refer to your car owner’s manual to find out where your fuse box is located.

Step 2: Test the grounding wire on the sending unit of the fuel tank. This is connected to your car’s fuel tank. You can do this by attaching the negative jumper cable to the vehicle’s frame, and the positive jumper cable to the sending unit’s grounding terminal. When the fuel gauge is working when the jumper cables are connected, it means you need to replace the grounding wire on the sending unit.

Step 3: Disconnect the wiring connected to the sending unit of the fuel gauge and then look at the fuel gauge. If the fuel gauge is now showing an empty reading, it means the fuel gauge is faulty and needs to be replaced. On the other hand, if your fuel gauge is showing a full reading, it means the sending unit is faulty and due for replacement.

Step 4: Check to confirm that all of the wirings is securely connected to the back of the fuel gauge. To do this, you have to remove the dashboard to have access to the instrument cluster. Consult your car owner’s manual as the process to do this varies from vehicle to vehicle.

Also, check the fuel gauge’s grounding wire by connecting the negative jumper cable to the car’s frame and the positive cable to the grounding terminal of the fuel gauge. Turn the ignition on and check the fuel gauge if it is working or not. If it is working, then the grounding wire should be replaced.





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