Replacing Xc90 Fuel Level Sending Unit: Step-By-Step Guide

The fuel level sending unit is located in the fuel tank and sends a constant signal to indicate the amount of fuel that remains. When the unit fails, the fuel gauge will not operate, and the check engine light may illuminate. The unit can be replaced, and the process involves removing the back seats, the carpet, and the fuel pump. The fuel level sending unit must then be removed from the fuel tank. However, this process can be complex and is best performed by a professional technician.

Disconnect the negative lead to the battery

Disconnecting the negative lead to the battery is a crucial step when working on your car, and it's important to do it safely. Here's a detailed guide on how to do it, specifically for replacing the fuel level sending unit on a Volvo XC90:

The negative battery terminal is connected to the vehicle's engine, body, and chassis. Disconnecting it first is essential to prevent any accidental short circuits. If you only disconnect the positive terminal, the entire engine and car body will still be connected to the battery, which can lead to potential electrical issues.

Steps to Disconnect the Negative Battery Terminal:

• Put on safety gear: Before you begin, it's important to prioritize your safety. Put on safety glasses and gloves, and remove any jewelry. These precautions will protect you from electrical hazards and potential battery acid exposure.
• Turn off the ignition: Make sure your XC90 is turned off. Attempting to remove the battery while the engine is running can damage sensitive electronics.
• Locate the battery: In most vehicles, the battery is located under the hood. However, some models may have it in the trunk. Refer to your Volvo XC90 owner's manual to identify the correct location.
• Identify the negative terminal: The negative terminal is usually denoted by a "-" symbol and is connected to a black battery cable. It is also typically located on the opposite side of the positive terminal, which has a "+" symbol and a red cable.
• Disconnect the negative terminal: Using a suitable wrench, loosen the nut on the negative terminal and remove it from the battery post. Ensure that the black cable is kept away from the battery terminals.
• Secure the cable: Make sure the negative cable doesn't touch any metal parts of the car to avoid accidental electrical shorts. You can tie it down or cover it with a cloth or plastic cup.
• Disconnect the positive terminal: Once the negative terminal is safely disconnected, you can proceed to disconnect the positive terminal using the same procedure.

Additional Precautions:

• It is recommended to let the car sit for a few minutes after disconnecting the negative lead to avoid any unwanted airbag deployments.
• Always work in a well-ventilated area when working with car batteries to avoid inhaling harmful fumes.
• If you're not comfortable or familiar with the process, consider seeking assistance from a professional technician or a repair shop.

By following these steps, you'll be able to safely disconnect the negative lead to the battery in your Volvo XC90, which is an important step when replacing the fuel level sending unit or performing other maintenance tasks.

Remove back seats

To remove the back seats of a Volvo XC90, you will need to disconnect the negative lead to the battery and let the car sit for a few minutes to avoid any unwanted airbag deployment.

The middle seat has an electrical connector that needs to be unhooked. Each seat is held in place by four 13mm bolts. The front bolts are easy to access after removing the plastic covers. There's a single tab you push down, and the plastic covers slide forward. To remove the rear bolts, you will need to remove the floor panel in the cargo space. The floor panel is not bolted down, so it is easy to remove. After removing all the bolts, the seats should come out easily.

If your XC90 has a third row of seats, you will need to remove the front two bolts and the middle five bolts, but only loosen the two bolts on each side so the frame starts to move. Then, lift the frame slightly and pull the carpet out.

Remove floor panel and carpet

To remove the floor panel and carpet of your Volvo XC90, start by disconnecting the negative battery cable. Loosen and remove the negative battery cable with a battery terminal wrench, turning counterclockwise to loosen it. Leave the vehicle for 10 minutes before proceeding, to avoid any unwanted airbag deployment.

Next, remove the back seats. Each seat is held on by four 13mm bolts. The front bolts are easy to get to after removing the plastic covers. There's a single tab you push down and the plastic covers slide forward. To remove the rear bolts, remove the floor panel in the cargo space. It's not bolted down, so it's easy to lift out. After removing all the bolts, the seats will come out easily.

Now, you can remove the carpet. There are two foam inserts that need to be taken out as well. This will reveal the two access panels for the fuel pump and level sensor.

Note: If your XC90 has a third row of seats, you don't need to remove the third row to access the fuel pump. Instead, lift the seat frame slightly and pull the carpet out. You may need to cut off a small piece of the carpet on each side where it goes up the wheel wells.

Remove access panel

To remove the access panel of your Volvo XC90, start by disconnecting the negative lead to the battery and letting the car sit for a few minutes to avoid any unwanted airbag deployment. Next, you will need to remove the back seats. If your car has a third row of seats, you will need to remove the front two and middle bolts, and then loosen the two bolts on each side so that the frame can be moved.

Once the seats are removed, the carpet can be lifted easily. There are also two foam inserts that need to be removed. This will reveal the two access panels for the fuel pump and level sensor.

On the driver's side, there is an access panel held on by four 10mm nuts. Remove these and work the access panel off the studs. One of these nuts is located under the seat frame and may be difficult to access. Once removed, carefully take out the rubber gasket from the access panel and unplug the wire, removing it from the gasket. Set the gasket aside.

Now, you need to remove the plastic lock ring. This can be difficult and you may need to buy or make a special tool to do this. Be very careful not to break off the lock ring "ears" as the writer of this forum post did. Once the lock ring is removed, you can remove the fuel pump hoses from the level sensor. There is a yellow plastic clip and an electrical connection (black wires) that need to be removed.

Vacuum up any dirt or debris around the edge and remove the o-ring. Be very careful not to vacuum up any gas.

Now you are ready to tie a wire or string to the fuel pump hoses. When you remove the pump, you can feed the new hoses back through. This is important as fishing the hoses from one side to the other would be a difficult task.

Repeat this process for the passenger side, which has more connections and hoses to deal with.

Remove lock ring

To remove the lock ring, you will need to purchase or make a specialised tool. A screwdriver and hammer will not be sufficient. You can buy a fuel tank lock ring tool online or from a car parts store. Alternatively, you can make your own tool using PVC from a hardware store.

Once you have the tool, follow these steps:

• Disconnect the negative lead to the battery and let the car sit for a few minutes to avoid any unwanted airbag deployment.
• Remove the back seats. For the Volvo XC90, there are four 13mm bolts holding each seat in place.
• Remove the floor panel in the cargo space.
• Lift out the seats.
• Remove the carpet and two foam inserts. This will reveal the two access panels for the fuel pump and level sensor.
• Remove the access panel on the driver's side (fuel level sensor side). It is held on by four 10mm nuts.
• Carefully remove the rubber gasket from the access panel and unplug the wire. Set the gasket aside.
• Remove the plastic lock ring using your specialised tool. Turn the lock ring counter-clockwise to loosen it. This may be difficult, so take your time and be careful not to break the "ears" of the lock ring.
• Remove the fuel pump hoses from the level sensor. There will be one yellow plastic clip and one electrical connection (black wires).
• Remove the level sensor from the tank, being careful not to lose the float in the tank.
• Vacuum up any dirt or gas around the edge of the tank and remove the o-ring.
• Tie a wire or string to the fuel pump hoses. This will be used to feed the new hoses through when you install the new pump.
• Repeat the process to remove the access panel on the passenger side (fuel pump side). This side has more connections and hoses to deal with, so be careful not to knock any of the electrical connections or fuel lines.
• Remove the lock ring on this side as well, using the specialised tool. This side should be easier than the driver's side.
• Remove the fuel pump assembly, being careful not to spill any fuel. Use a turkey baster or similar tool to remove any fuel that may be in the basket.
• Unclip the float, being careful not to drop it into the tank.
• Pull out the fuel pump, bringing the string or wire attached to the hoses with it.
• Remove the string or wire from the old pump hoses.

Now you are ready to install your new fuel pump and fuel level sensor. Follow the steps in reverse, making sure to tighten the lock rings securely and replace the gaskets and seals.

Frequently asked questions