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GM Gas Tank Replacement

Getting "tanked" is easier than you think!

Few of us ever dwell on the fuel we use to power our favorite ride. Except for price fluctuations and an occasional gas shortage, we pump and go. After all, the receptacle that holds that precious fluid is out of sight and out of mind. Over time, age, rust, road damage and other hazards can take a severe toll on this all-important part, and a gasoline leak is highly dangerous. At best, a regular inspection of that venerable old tank is a wise idea—don't wait till it's too late. If you smell gas in the garage, always check your tank for leaks!

If you're interested in entering your car in shows, then a clean, correctly plated fuel tank is a must-have item. Here we will examine the removal and replacement of a GM A-body fuel tank, and show you just how easy the swap can be. No special tools are required, and once the existing tank is siphoned as empty as possible, the removal takes only a few minutes. Any remaining gas can then be funneled into a five-gallon gas can for reuse.

Our vehicle is a mid-Sixties A-body, and while the tank shape and size is the same for many A-body vehicles, the filler-neck length and shape can change drastically depending on the bumper design. Most tank suppliers will also stock replacement sending units and new straps to secure the tank. If your gas gauge is working fine, then a new sender is probably not necessary, but new support straps are always a good idea.

Original Tank

This factory tank has seen more than three decades of use and has developed a fuel leak at the rear seam. There's no such thing as a small gas leak! The process to fix this original or install a new tank is just as much work, but the end result with the new tank is dramatic. Check with your restoration-tank supplier to make sure the new filler neck is the same. If it isn't, or not available at all, most radiator-repair shops can remove your original filler neck and replace it in the new tank. Check this area before ordering the new tank.

Disconnect Items

At the front part of the tank you'll find the sending-unit connector, ground strap (if necessary) and fuel pickup line. All of these must be disconnected prior to dropping out the tank. The ground wire (if applicable) is screwed to the bottom of the floorboard, usually with a 5/16-inch metal screw. The sending unit plug simply pulls off the connection pin, and the fuel line is self-explanatory. If your gas gauge is working fine, then there's no need to replace the sending unit. Remove it and transfer the sender to the new tank.

Remove Straps

Using a 9/16-inch socket, loosen the nuts on the tank retaining straps, leaving them attached to the carriage bolts by a few threads. Then, either using a lift or supporting the tank with the help of a friend or a floorjack, remove the two nuts. The straps can then be dropped down out of the way and the tank is ready to be removed. How simple is that? The longest part of this 15-minute job is siphoning the gas out of the tank. Driving the car until the tank is almost empty speeds this process.

Tank Removal

The tank filler neck can now be pulled free of the rear bumper and the fuel tank dropped out of the car. Being almost empty, the tank is relatively light but bulky. Here you see the clean lines created on the original tank by the support straps. With the tank removed, it's a good idea to clean and paint the floorboards and frame rails while they're accessible. The remaining fuel in the tank can be funneled into your 5-gallon gas can. Remember that gas fumes are dangerous: No smoking or open flame around the tank!

Finished

The new tank is installed by reversing the removal process. If you are replacing the support straps, install them before positioning the tank. If the carriage bolts and nuts are in good shape, wire-wheel the dirt and rust from them and reposition the bolt heads in the slide-in pockets provided in the vehicle. Reattach the straps and secure the nuts in place. DO NOT OVERTIGHTEN the nuts. Make sure the tank isn't able to move within the straps and stop there. The weight of the fuel in the tank also helps secure it. Carefully refill the tank with the fuel you removed, then head to the gas station and fill 'er up.