Replacing Fuel Level Sensor: Step-By-Step Guide For Diy Mechanics

A fuel level sensor, or gasoline gauge, is a device that shows the amount of fuel remaining in a vehicle's tank. It is made up of two components: the sensor system and the fuel indicator. The sensor device often runs on a float attached to a potentiometer. When the vehicle tank runs dry, the float falls, increasing the resistance. At the same time, the fuel indicator system calculates and displays the volume of electric current passing through the transmitting system. If your tank is full, the gauge will read 'F', but if it's empty, it will read 'E'. While a professional will charge around $450 to install a fuel sensor, it is possible to change it yourself for under $100.

Characteristics of Changing a Fuel Level Sensor

Disconnect the battery and fuel tank

Disconnecting the battery and fuel tank is an important step when changing a fuel level sensor. This will disable the power to the fuel pump and sending unit.

First, park your vehicle on a flat, hard surface and engage the parking brake. If your vehicle is automatic, make sure the transmission is in park. If it's a manual vehicle, put it in first gear. Place wheel chocks around the front tires, as the rear of the vehicle will be lifted.

Now, open the vehicle's hood and locate the battery. Identify the ground cable, which is the negative battery cable, and take it off the battery's negative post. This will cut off the power to the fuel system.

Next, you will need to lower the fuel tank slightly to access the harness attached to it. Place a transmission jack or similar device under the fuel tank and loosen and remove the straps holding the tank in place. You will then need to feel for the harness, which is attached to the tank. This is the harness for the fuel pump or sending unit, and you will need to disconnect it.

At this point, you have successfully disconnected the battery and fuel tank, and you can proceed to the next steps of changing the fuel level sensor. Remember to exercise caution and refer to a professional mechanic if you are unsure about any part of the process.

Remove the fuel tank

Removing the Fuel Tank

Before beginning the process of removing the fuel tank, ensure that your vehicle is parked on a flat, hard surface. For automatic vehicles, the transmission should be in park, and for manuals, it should be in first gear. Place wheel chocks around the front tires and engage the parking brake to prevent the vehicle from moving.

Next, locate the fuel tank under the vehicle and place a transmission jack or similar jack under it. Loosen and remove the straps holding the fuel tank in place. Depending on the vehicle, you may need to disconnect the harness from the connector by reaching up to the top of the fuel tank.

If your vehicle is a 1996 model or newer, it likely has a return fuel charcoal canister attached to the vent hose. In this case, you will need to lower the fuel tank further to access and remove the vent hose. Remove the clamp and small vent hose to allow more clearance for the fuel tank removal.

Now, you can proceed to remove the fuel filler neck. Twist and pull it out of the rubber hose, guiding it out of the way. Also, remember to remove the clamp on the rubber hose attached to the fuel filler neck.

At this point, you should be able to remove the fuel tank from the vehicle. Ensure that you have transferred any remaining fuel out of the tank before proceeding. It is recommended to have the vehicle at a quarter tank of fuel or less when performing this step.

Before reinstalling the fuel tank, take the opportunity to inspect and clean the rubber hose for any cracks or debris. If there are any cracks, it is important to replace the rubber hose to prevent leaks.

By following these steps, you will be able to safely and effectively remove the fuel tank from your vehicle, allowing you to access and replace the fuel level sensor or perform any other necessary maintenance tasks.

Detach the transmitting device

To detach the transmitting device, you will need to remove the clips on the electrical attachment at the top of the device. It is important to note that you should not detach the gas pipe during this step, as fuel will come out of the tank. Next, using a screwdriver and hammer, rotate the lock ring at the top of the transmitting device to align the lock tabs and channels. To make this process smoother, spray the lock ring with lubricating oil to minimise friction when removing it. Once the lock ring is off, simply take the transmitting device out of the gas tank.

To ensure a smooth process, it is recommended to have the necessary tools, such as a screwdriver and hammer, within reach before beginning. Additionally, having a friend assist you in holding the tank, with each person on either end, can be helpful. Remember to always exercise caution when working with fuel systems and follow safety guidelines to prevent accidents.

Before detaching the transmitting device, it is important to ensure that you have completed the previous steps, including closing the gas and power lines, and removing the spare tire if necessary. It is also crucial to work in a well-ventilated area and wear appropriate protective gear, such as gloves and safety goggles, to safeguard against any potential fuel leaks or spills.

In some cases, you may encounter difficulty accessing the transmitting unit due to insufficient space. In such instances, it is necessary to reduce the volume of fuel in the tank to gain better access. Lower the fuel level to approximately one-quarter of the tank's capacity to create the required space to work comfortably. Remember to properly dispose of or store any removed fuel in a safe and environmentally friendly manner.

Remove the fuel level sensor

To remove the fuel level sensor, you will need to first close the gas and power lines. Remove the negative battery cable, and if you have one, take out the spare tire by raising the rear hatch or opening the trunk. Detach the gas and electric power cables from the fuel tank.

Now, detach the tank itself. Unclip the electrical cables using a small screwdriver and remove the tank holders. Take out the bolts supporting the tank under the vehicle. Then, carefully lower the gas tank. You may need a friend to help hold the tank, with one person on either end.

The next step is to remove the transmitting device. Remove the clips on the electrical attachment at the top of the device—be careful not to detach the gas pipe, as fuel will escape from the tank. Using a screwdriver and hammer, rotate the lock ring to align the lock tabs and channels. Apply some lubricating oil to the lock ring as you remove it to reduce friction. Once the lock ring is off, take out the transmitting device.

Finally, you can remove the fuel level sensor. It is usually situated at the bottom of the transmitting device. Remove the clip from the harness and slide off the sensor.

Fit the new sensor

To fit the new sensor, you will need to reverse the steps you took to remove the old one.

First, consult your vehicle's owner's manual or a store associate to make sure you are buying the correct part. Once you have the new sensor, slide it into the place of the old one.

Next, you will need to reconnect the harness to the connector. Reach up to the top of the fuel tank to access it. Then, raise the fuel tank to the vent hose and attach the vent hose using a new clamp. Tighten the clamp until the hose will not twist, and then give it an additional turn of 1/8.

After that, raise the fuel tank up to align the fuel filler neck to the cutaway. Tighten the clamp and prevent the fuel filler neck from moving.

Finally, raise the fuel tank up to the harness and connect the fuel pump or sending unit harness to the fuel tank connector.

The whole process should take around two hours to reassemble.

Frequently asked questions