Fuel tanks are a forgotten part on our vehicles and other gasoline powered devices such as generators, lawn motors and recreational equipment — until they start to leak.
Many current fuel tanks are made of plastic to withstand the corrosive effects of some fuels, but many fuel tanks have been made of steel and they can rust out.
For some vehicles and equipment the only solution is to either try and repair the tank or have a custom one built. Repairing a tank is usually cheaper.
Water is the culprit that causes most internal tank damage. The water usually comes from the air and moisture inside the tank that condenses when temperatures change, much in the same way water in the air condenses on a glass jar removed from the refrigerator.
Over time, this water accumulates in the bottom of the tank, as water is heavier than fuel.
Adding alcohol (gas line antifreeze) to the fuel can help remove water, although many gasolines already contain ethanol already.
The alcohol mixes with the water and fuel and is then pumped from the tank to the engine.
If there is too much water, the first clue that you have a problem is usually a puddle of fuel below the vehicle and a strong smell of gasoline.
Recently, I had to repair a motorcycle gas tank and there was a lot of varnish, gum deposits and rust in it.
The tank metal seemed solid but during the repair process I did find a couple pin holes in the metal. The first step is to clean the varnish and gum deposits from the tank.
I used a repair kit from PORS 15 but there are several manufacturers of fuel tank coating repair kits.
After sealing the tank openings (except the filler) with duct tape or corks, the cleaner/degreaser is mixed with an equal amount of warm water and poured into the tank. Seal the filler and start rotating the tank for 20 to 40 minutes so the cleaner gets to all parts of the tank.
Some use a mixture of baking soda and water, CLR or even acetone to clean the inside of the tank. What ever you use, be sure to use protective gloves and eye ware and dispose of the chemicals properly.
I also add about half a pound of ¼-inch nuts inside the tank to help mechanically clean the tank. The nuts can be removed with a magnet afterwards.
After flushing the tank with water, the next step is to add metal prep the tank. This is basically a phosphoric acid solution that dissolves rust, etches the metal and neutralizes the cleaning solution.
Again, rotate the tank so all parts are covered for about 20 to 40 minutes. Do not leave the metal prep in the tank for long periods as it will eventually eat into the metal.
If any pinholes in the tank appear, they can be repaired on the outside using several methods. I prefer to solder a patch over the hole with an electric soldering gun (never do this on a tank that hasn’t been thoroughly cleaned inside. Gasoline can still be in the tank seams and could cause an explosion!)
There are also epoxy’s that can be used to repair tanks. If there are only small pinholes, you may be able to go directly to the final step.
Rinse the tank again and then let it dry completely inside. A hair drier will help it dry faster. The last step is to pour the mixed coating solution into the tank, slowly rotate the tank to coat all areas and then pour out any excess coating solution.
The coating seals small pinholes and protects the tank from further rusting and corrosive fuels. After a dying time of about four days, the tank is ready to use.
Repairing a fuel tank is an economical way of getting your vehicle back on the road, and for classic or antique vehicles it may be the only way to restore the vehicle back to original condition.
