Cadillac Deville: Replacing The Fuel Level Sensor

The fuel level sensor in the Cadillac DeVille is known to malfunction, causing the fuel gauge to behave erratically. This issue can be fixed by replacing the sensor or the entire fuel pump module, especially in older vehicles. While it is possible to replace the sensor yourself, it is a complex process that may require professional help.

Drop the fuel tank and remove the fuel pump

To replace the fuel level sensor in a Cadillac DeVille, you will need to drop the fuel tank and remove the fuel pump. Here is a step-by-step guide to help you through the process:

First, locate the fuel tank and ensure you have the necessary tools and safety equipment, including gloves and eye protection. Place the car on a level surface and engage the parking brake.

Next, you will need to drain the fuel tank. You can do this by removing the rubber hose behind the filler neck and siphoning the fuel, or by using a hand-held transfer pump from an auto parts store. Ensure you are careful and avoid any open flames or sparks during this process.

Once the tank is drained, you can begin to remove the fuel pump. Loosen and remove the bolts securing the fuel pump to the tank. You may need to remove a rubber ring or gasket to access the bolts. Be careful not to damage the surrounding components.

Now, you will need to detach the electrical connector and any fuel lines connected to the pump. Label or mark the lines to ensure proper reconnection during installation. Carefully lift and remove the fuel pump assembly from the tank.

With the fuel pump removed, you should now be able to access and replace the fuel level sensor. Install the new sensor and reverse the removal process to reinstall the fuel pump and refuel the vehicle. Ensure all connections are secure and properly sealed before adding fuel and testing the vehicle.

It is important to note that working with fuel can be dangerous, and it is recommended to have a qualified mechanic or technician perform these tasks if you are uncomfortable or unfamiliar with the procedure.

Access the fuel pump through the trunk

To access the fuel pump through the trunk of your Cadillac DeVille, you'll first need to identify the access panel. Remove the trunk mat and you should see an obvious access hatch in the trunk floor.

Once you've located the access panel, you'll need to remove it to access the fuel pump and sending unit assembly. This is where you'll be able to replace the fuel level sensor.

Before beginning any work, it's important to relieve the pressure in the fuel system. One way to do this is by removing the fuel pump fuse and then running the engine until it dies. Alternatively, you can locate the fuel pressure test port in the fuel rail and use a rag to absorb the fuel as you release the pressure.

It's worth noting that some pump modules have a heavy-duty 4-blade flat electrical connector, so you may need to splice in a new harness pigtail and connector to the existing body harness. Diagrams for this process should be included with the new pump module.

In addition, while you have the fuel pump out of the tank, it's recommended to replace the entire pump module, especially considering the age of these vehicles. This can help prevent future issues and save you time and effort in the long run.

Relieve pressure on the fuel system

To relieve pressure on the fuel system of a 2002 STS Cadillac, you must first turn off the engine. Then, remove the engine beauty cover. You will find a black plastic cap on the fuel rail, which is located just in front of the front seat passenger's toes. This cap covers a Schrader (tire) valve. Place a rag under the rail and then release the fuel pressure by turning the valve, in the same way you would to let air out of a tire.

Check the wiring and clean them

To check the wiring, you will need to locate the fuel tank pressure sensor. This can be found on the fuel pump sending unit in your Cadillac DeVille. Once you have located the sensor, you can inspect the wiring for any signs of damage or corrosion. If the wiring looks dirty or corroded, you can clean it using a wire brush or a contact cleaner. Be gentle when cleaning the wiring, as they are delicate and can be easily damaged.

It is important to ensure that the wiring is clean and free of debris before proceeding with any further repairs or replacements. Dirty or corroded wiring can cause electrical issues and impact the performance of your vehicle. By cleaning the wiring, you can help improve the overall performance and longevity of your Cadillac DeVille's fuel system.

In some cases, the sensor itself may be faulty, and cleaning the wiring may not resolve the issue. If the problem persists, you may need to replace the fuel tank pressure sensor. This is a relatively inexpensive part and can be purchased online or from a local auto parts store.

Additionally, it is recommended to refer to the Technical Service Bulletin (TSB) for your vehicle. A TSB is an advisory that provides information to dealer mechanics about known issues and how to repair them. Checking the TSB can help you identify if there are any specific recommendations or recalls related to the fuel tank pressure sensor for your Cadillac DeVille.

Replace the complete fuel pump module

To replace the complete fuel pump module in a Cadillac DeVille, you will need to first relieve the pressure in the fuel system. With the engine off, open the engine beauty cover and locate the fuel rail, which is just in front of the front seat passenger's toes. There will be a black plastic cap covering a Schrader (tire) valve. Place a rag under the rail and then bleed off the fuel pressure by releasing the valve, in the same way, you would let air out of a tire.

Next, you will need to remove the fuel pump from the gas tank. This can be a tricky process, as the tolerances are very tight. You may need to refer to a Chilton's manual for specific instructions on how to remove the fuel pump, but essentially, you will need to pull it up until it stops, lean it toward the back of the fuel tank, and then slide it out.

Once the fuel pump is removed, you can install the new fuel pump module. This should include a new harness pigtail and connector that can be spliced into the existing body harness. Diagrams should be included with the new module to help with this process.

Finally, reinstall the fuel pump into the gas tank, using the reverse of the removal process, and reconnect the fuel lines and electrical connections. Be sure to check all connections for leaks before starting the engine.

Frequently asked questions