Replacing The Cj5 Fuel Tank: A Step-By-Step Guide

If you're looking to replace the fuel tank in your Jeep CJ5, there are a few things you should know. First, check the age of your vehicle and the condition of the current fuel tank. Severe weather conditions and vehicle age can cause issues with the fuel tank, and if there is rust damage, it will need to be replaced. You'll also want to determine the correct fuel tank for your model of CJ5, as different models have different requirements. For example, the 1955-1969 Jeep CJ5 has an 11-gallon fuel tank mounted under the driver's seat, while later models have rear-mounted fuel tanks. Once you've sourced the correct replacement tank, you can begin the process of removing the old tank and installing the new one, taking care to follow safety procedures when working with fuel.

Removing the fuel tank

To remove the fuel tank from a Jeep CJ5, you will need to first drain the tank as much as possible. Then, identify the bolts holding the tank in place and remove them. There should be three bolts: two rear corner bolts and one forward center bolt/bracket. Once the bolts are removed, you may need to twist and work the tank to get it clear of the frame. Be careful not to damage the fuel lines or the fuel pump.

If your Jeep CJ5 has a fuel filter, it may be necessary to replace it if it is clogged with gunk or debris. Additionally, check the fuel lines, clean out the tank, and inspect the fuel pump to ensure they are all in good condition.

It is important to work in a well-ventilated area when performing this task, as gasoline fumes can be dangerous. Always be mindful of potential sparks and keep the area clear of any ignition sources.

When removing the fuel tank, you may also want to inspect the skid plate and clean it if necessary. Reusing the skid plate is usually possible, but ensure there is no debris or damage that could affect the new tank.

Buying a new fuel tank

When buying a new fuel tank for your CJ5, there are a few things to keep in mind. Firstly, make sure you know the model year of your CJ5, as the fuel tank design changed over the years. You'll also want to consider the type of fuel tank material you prefer, such as steel or polyethylene.

For CJ5 models from 1955 to 1970, you can choose between steel or polyethylene fuel tanks. A steel tank in this category is available from Omix-Ada, featuring a 6.5" filler neck and a 2.25" inlet. Polyethylene options include 11-gallon tanks from MTS, available for both the driver and passenger side, and a 15-gallon tank from Gas Tank Depot, which also offers a steel alternative.

CJ5 models from 1971 to 1976 have a variety of options available. For a stock replacement, you can find 15-gallon steel tanks from brands like Dorman, Crown Automotive, Sherman, and Holley Sniper. If you're looking for a larger capacity, Tanks Inc. offers an EFI-ready 20-gallon steel tank. Polyethylene options include a 15-gallon tank from MTS and a 21-gallon tank from Gas Tank Depot, which can be a suitable replacement for the standard 15-gallon tank.

CJ5 models from 1977 to 1983 have a few fuel tank options as well. You can find steel tanks from Sherman and Goodmark, as well as polyethylene alternatives from OMIX-ADA and Gas Tank Depot.

When purchasing a new fuel tank, it is important to consider the ease of installation, corrosion resistance, and the overall fit and compatibility with your CJ5 model. Additionally, always refer to the manufacturer's instructions and safety guidelines when working with fuel systems.

Installing the new fuel tank

Now that you have successfully removed the old fuel tank, it's time to install the new one. Here's a step-by-step guide on how to do it:

Step 1: Prepare the new fuel tank

Before you begin the installation process, gather all the necessary parts and components, including the new fuel tank, fuel hoses, O-rings, clamps, and any other hardware. It is also recommended to have a fuel tank skid plate to protect the tank from debris and damage. Ensure that the new fuel tank is the correct type and size for your CJ5 model.

Step 2: Position the new fuel tank

Place the new fuel tank into the vehicle, ensuring it is securely mounted and aligned correctly. You may need to use a jack to lower the tank into place, as well as twist and work it to clear the frame, especially if you are installing a larger tank. Ensure the tank is secure and does not move around.

Step 3: Connect the fuel lines

Disconnect the fuel lines from the old tank and connect them to the new tank. Typically, there are two hoses: one for the main fuel line and one for the return line. Ensure that the connections are secure and tight to prevent leaks.

Step 4: Connect the sending unit

Install the sending unit into the new fuel tank. The sending unit is responsible for sending fuel level information to the gauge in your vehicle. Ensure that the float is in the middle of the tank for optimum reading. You may need to test and adjust the sending unit to ensure the gauge reads correctly for "Empty" and "Full".

Step 5: Connect the electrical connections

Connect the sending unit gas gauge wire and the ground wire to the frame rail. Ensure that all electrical connections are secure and properly routed.

Step 6: Fill the fuel tank

Before completely bolting down the new fuel tank, fill it with fuel to make it easier to handle. You can use a funnel to avoid spills. Ensure that the fuel cap is securely tightened.

Step 7: Secure the fuel tank

Use bolts to securely fasten the fuel tank to the vehicle's frame. Ensure that all bolts are tight and secure.

Step 8: Test the installation

Once the new fuel tank is installed, test it by starting the vehicle and checking for any leaks. Ensure that the fuel gauge is reading correctly.

Step 9: Clean up

Clean up the work area and dispose of any old parts, fluids, or debris properly. Ensure that there are no fuel spills or leaks.

Step 10: Regular maintenance

To maintain your new fuel tank and prevent future issues, regularly inspect it for leaks, damage, or corrosion. Keep the area around the tank clean and free of debris.

By following these steps, you can successfully install a new fuel tank in your CJ5 and ensure that it functions properly. Remember to refer to your owner's manual or seek professional assistance if you have any questions or concerns during the installation process.

Filling the new tank with fuel

Filling your new CJ5 fuel tank with fuel is a straightforward process, but it's important to take the necessary precautions for your safety. Here is a step-by-step guide:

Prepare the Fuel Tank:

Before filling the tank, ensure that the fuel tank gauge is working correctly. Adjust the sending unit tabs to read "Empty" and "Full" accurately. Also, check that the float is in the middle of the tank for an optimum reading.

Filling the Fuel Tank:

• When you go to the gas station, park your vehicle and remove the gas cap.
• Take the fuel nozzle and insert it into the fuel filler neck of your CJ5.
• Begin filling the tank slowly. Keep a steady pace and avoid overfilling.
• Once the tank is full, or you have added the desired amount of fuel, stop the nozzle and replace the gas cap securely.

Safety Precautions:

• Always touch the metal on your vehicle before filling the tank to discharge any static electricity from your body.
• Never fill a gas can while it's inside your vehicle, especially if your car has a carpeted trunk or floor, as it may not be grounded.
• Keep the gas nozzle in contact with the gas tank filler neck during filling to minimise static electricity build-up.
• Only fill the tank to 95% capacity to allow for fuel expansion.
• If you need to transport gas cans, place them in the trunk or truck bed, and keep the trunk slightly open for ventilation.
• Never add gas to a hot engine, as the vapours can ignite.

By following these steps and precautions, you can safely fill your new CJ5 fuel tank with fuel and get back on the road.

Testing the new tank

Pressure Testing:

Fuel tank pressure testing helps identify any leaks or faulty components and ensures the tank can maintain the correct pressure for efficient fuel delivery and evaporative emissions control. Here's a step-by-step process:

• Park your Jeep on a level surface and engage the parking brake.
• Seal off all openings of the fuel tank.
• Introduce compressed air into the tank to reach the specified pressure.
• Monitor the pressure level over time using a pressure gauge.
• Inspect the tank and its components for any leaks using a soapy water solution.

Testing for Water Contamination:

Water in the fuel tank can lead to engine issues and damage, so it's important to ensure your new tank is dry.

• Use a special water-detecting paste, such as Kolor Kut Water Finding Paste.
• Apply the paste to a rod or weighted string and dip it to the bottom of the tank.
• If the paste turns red, it indicates the presence of water and provides a visual indication of the water depth.

Fuel Gauge Sending Unit Test:

To ensure your fuel gauge reads correctly, you'll need to test the sending unit:

• Hook up the gas gauge sending unit wire and ground wire.
• Turn the key in the ignition.
• Adjust the tabs on the sending unit so that the gauge reads correctly for both "Empty" and "Full".
• Ensure the float is in the middle of the tank for optimum reading accuracy.

Test Drive:

Finally, take your Jeep for a test drive to ensure the new tank and fuel system are functioning correctly. Check for any warning lights on the dashboard and make sure the engine runs smoothly.

Frequently asked questions