How to repair a leaking double wall fuel tank

Ensure safety by isolating the tank from all ignition sources. Turn off any nearby electrical equipment, heating devices, or engines that could spark a fire. Ventilate the surrounding area thoroughly to disperse any accumulated fuel vapors. Wear appropriate personal protective equipment, including chemical-resistant gloves, safety goggles, and flame-retardant clothing.

Conduct a visual inspection of both the inner and outer walls of the tank. Look for signs of corrosion, cracks, or damaged seals. For harder-to-detect leaks, use a fuel vapor detector or apply a soapy water solution to the tank surface—bubbles will form at the leak point when the solution comes into contact with escaping fuel vapors.

Once the leak is identified, drain the fuel from the tank to eliminate pressure and prevent further spillage during repair. Use a dedicated fuel transfer system to move the fuel to a temporary, approved storage container. Ensure the transfer process is done in a well-ventilated area and avoid any sudden movements that could cause splashing.

Clean the surface around the leak thoroughly. Remove any dirt, rust, or fuel residues using a solvent that is compatible with the tank material. Sand the area gently to create a rough surface, which will improve adhesion. Wipe the surface dry with a clean, lint-free cloth to ensure no moisture remains.

Select a repair material designed for use with fuel tanks and compatible with the tank's construction material. Apply according to the manufacturer's instructions, ensuring full coverage of the leak and a sufficient seal around the damaged area. Allow the repair material to cure completely—curing time may vary depending on the product and environmental conditions.

After the repair material has fully cured, conduct a leak test to verify effectiveness. Reinstall the tank (if removed) and gradually refill it with a small amount of fuel. Monitor the repair area closely for any signs of leakage. If no leaks are detected, continue refilling and perform a final inspection to ensure the repair holds under normal operating conditions.