An Easy Fuel Tank Repair Method

So my gas tank was leaking. In today’s world of high fuel costs this was something I wanted to fix as soon as possible.

Using the siphon method I pulled out all of the gasoline I could and stored it in a fuel safe container and set about removing the tank from the truck. On this particular vehicle the tank was secured with two steel bands that bolted into the frame members. In addition to the bands the tank itself was resting on a projecting frame member to keep it from shifting or bouncing on rough terrain.

With all the fuel removed the tank would be light so I had no worries there, but there was more to this removal than weight alone. The tank has several connections that must be taken care of before complete removal would be possible. First there was the fill tube connection. This was a rigid connection and not something that could be done after the retaining straps had been removed. Crawling under and shining a light onto the fill tube area I saw there was a clamp assembly attaching the fill tube to a spout projecting from the side of the tank. Removing the clamp and the three screws holding the fill hole assembly to the side of the bed I was able to remove the fill tube and spout as a unit. It was now time to drop the straps and lower the tank to the ground where I could get at the rest of the connections.

With the tank on the ground I could see all the other connections that needed to go before i could finish up the job. First was the electrical connections. This was a latched plug and socket assembly and carried the connections for the fuel pump which was located inside the tank and the wiring needed for the fuel level to register on the gauge. This popped loose quite easily and the only remaining connections were the gas output hose from the pump and the fuel return line from the engine bay. These were simply clamped on and I tagged each one so as not to mix them up on reassembly.

With the tank lowered and released from all connections I was ready to pull it out from under the truck and repair it. Repairing a fuel tank can be a dangerous job if one doesn’t go about it correctly. The tank still has a small amount of gasoline inside and the fuel is steadily vaporizing making the possibility of explosion very real. Unless you are safely equipped for such an endeavor you do not want to introduce any sort of flame or welding repair techniques.

Most tank repairs can be done very easily using an auto parts store tank repair kit. This is actually a fiberglass body putty repair with a fuel safe liner to place against the body of the tank. The only instance where I do not like to use this sort of repair is when the hole in the tank is on the bottom and also located under a restraining strap. This is an almost guaranteed re-fix in the near future as the strap will wear through the repair material and the leak will return.

I was fortunate in that my leak had formed on the side of the tank just under the seam where the two halves of the tank were welded during it’s construction. Using sandpaper and a putty knife I was able to clean the area down to bare shiny metal. The repair kit is a special formulation of the standard fiberglass body putty used in repair shops. The catalyst that sets and hardens the putty is gasoline resistant as are the resins used in the fiberglass material. A vapor barrier patch is included as well.

Taking some 100 grit sandpaper I roughed up the area around the hole. And using a small punch tool I pushed in the tiny hole so that no rusted or sharp edges protruded and then used the included adhesive to cement the patch onto and over the hole. I mixed the packet of fiberglass with the tube of resin and using the putty knife smeared a generous portion onto and around the patch. The patch seals the hole and the putty, after it dries, supports the patch and prevents it from peeling off. Fiberglass repairs are iron hard and will resist even stone strikes with no ill effects.

I am a strong believer is preventative maintenance and this would be a good time to swap out an old fuel pump if your vehicle is getting on in miles. Doing this now could save you a tow bill and another trip down tank removal road. And since you are already down and dirty from today’s work you may want to locate and change out that fuel filter as well. It is usually buried up in the frame somewhere. If you follow the output line from the tank it will lead you straight to it.

Reassembly is very simple in that I reconnect the fuel lines, reconnect the wiring harness and lift the tank back into position. Secure the straps and replace the fill tube assembly and replace the gasoline. But I wasn’t quite done yet. Most fuel systems will need priming after being disconnected. Remember, I pulled off the lines and the tank thus draining fuel away from the engine. Most cars have a fuel pump relay and it’s job is to cause the fuel pump to run for 3 to 5 seconds when you first turn on the key. This pulls fuel from the tank and sends it to the injectors. So I turned the key on and waited 5 seconds. Repeating this a few times before I actually tried to start the engine. It will prime the system and prevent over heating of the starter motor.

Once the engine was running I checked around and looked for fuel leaks. Using my nose as well as my eyes. And the next time I fueled up, I made sure the fuel level in the tank was above the level of the repair. And checked for leaks again.