A fuel leak from a gas tank can not only be costly but can be very dangerous if the leak were to catch on fire. Several things can cause a gas leak including rusting of the straps holding the tank, physical damage and old age. Knowing how to fix a gas tank properly can keep you from high maintenance costs and personal injury.
Before beginning work on a leaking gas tank it is important that you clean it properly. Drain the gasoline from the engine using a siphon then run the engine until it is completely out of gas and stalls. This way there is no gas inside any of the engine parts when you begin work. Disconnect any fuel pumps and wires that lead to the gas tank from the engine. Remove the tank by unscrewing it and removing any metal straps holding it down. To remove all the bolts from a car engine you may need to use a ratchet tool with an extension. It is recommended that you have someone hold up the tank as you remove all the bolts. When removing the tank you will need to remove the pump from the inside. The pump is held on by a metal ring which you can remove by lightly tapping it with a screwdriver against one of its grooves. The ring should come off.
Once you have removed the fuel pump ring it is time to remove the straps from around the tank. Some tanks will have straps held on by Velcro while some use bolts. Remove as necessary. Check for the leak area by closely examining the tank. Check first where the straps used to live as these areas are subject to moisture collection and rust. Once you have located the leak and have rinsed out the gas tank to prevent and further leaking, sand the tank by the leak area until the paint or coating surrounding the tank is removed. There may be a plate on the bottom of the gas tank that will need to be removed to check for further leaks.
Use a pick to dig out any rust from the leak area. It is a good idea to clean rust form any other parts of the tank where decay is apparent to prevent further leaks. Once you have removed all the rust from the tank, use gas tank repair putty to fill the hole in the tank. This putty can be bought at most hardware or auto supply stores. Each putty takes a different amount of time to dry so follow the manufacturer instructions carefully. Once the putty is dry reattach the bottom plate to the gas tank and repaint the tank if necessary.
