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Fuel Tank Swap

Contributed By: Eric Lusk

Okay, here's the step-by-step on what I did to get rid of the factory fuel tank in my '82 Wag... I'm writing this from memory, so I may append this later on.
Oh, yeah, and I hope to have pictures of the finished product soon, assuming the film turns out okay... I'll post them when I get 'em.

First of all, before you begin messing around with the fuel tank in your fsj, remember that you're dealing with explosive materials here! People seem to forget this when they're moving around a piece of metal with 20+ pounds of gasoline in it....

First of all, before you start removing anything, make sure you have the necessary parts to undo what you're doing. In other words, measure all the hoses going to your tank, and buy new, preferably more than you think you're going to need, since this still won't be enough. And don't forget to make sure that all hoses are rated for gasoline. There's nothing like having to replace fuel filters every few miles, because they keep clogging up with rubber.

I found I needed the following materials to install my new tank:

  • 10 feet of 5/16 fuel hose
  • 12 feet of steel strapping, stronger than the cheap plumbing type
  • 3 feet of 1" id fuel hose
  • 3 feet of 3/4" id fuel hose
  • 3/8 - 16 tap
  • four stainless steel 3/8 - 16 X 1" bolts, with nuts, washers, and lockwashers (I used stainless only because it will last longer)
  • 12 feet of 2" wide baler belting
  • and one free day

The first trick involves removing the old tank, which was barely held in, due to the frame on my truck rusting out. You will need to lift the front and/or rear of your truck, if it's stock height, since the tank will be about 2-3 in. higher than the bottom of your frame.

After supporting the tank with a jack, I attempted to remove the bolts along the frame, which proved useless, since the only thing left on most of them was the heads. From there, there were only 3 bolts holding the tank in, along the inside, mounting it to the body. One is at the front, and the other 2 are toward the rear. It may take some searching to find them all. Once these are removed, lower the tank far enough that you can access the hoses going into it. On my tank, there were 4 small hoses, 2 to the charcoal canister, the return line, and the line to the fuel pump. Don't forget, there are also 2 larger hoses, one filler hose, and 1 vent hose at the rear.

You can also remove the sending unit wires at this point, which should just need to be pulled off.

Once the hoses and wires have been removed/cut/mangled enough, you can set the tank on the ground. If you didn't think to run the tank almost empty, you will think of this now, as you struggle with the extra weight of the fuel. Whoops.

After contorting yourself into various unnatural positions, straining muscles you didn't know you had, you can pull the tank out from underneath the truck, being careful not to just drag it, as this could throw sparks, which would be bad. Once the tank is free, get it as far away from the truck as possible, as it is a curse, and best left to rot alone somewhere, where it can no longer affect your fsj's frame.

The replacement tank I found was out of a Do*g* Ramcharger, around '82. It was a poly tank, like the factory one, but otherwise very different. This was the best fit I could find for my spare tire area, and also happened to provide about 14 more gallons of fuel capacity, which tends to be a good thing for fsjs.

You may have to put a small amount of fuel in the new tank before you put it in place, so you can find out which line goes to your fuel pump, in the event this line isn't labeled. Mine wasn't, and resulted in a few hours of wasted time. After you've routed the hoses, then you can jack the new tank into place. By the way, the spare tire carrier is fairly simple to remove, just a matter of finding the right cotter pin and removing it, then beating away rust with a hammer until the assembly falls out.

So, with hoses routed, jack the new tank into position, and hold it in place with the steel strapping. To keep the strapping from rubbing through the tank, I used baler belting, which is a reinforced rubber/canvas material. You can find this at farm supply and hardware stores. Mine cost about $.45 a foot.

After cutting the strapping to fit, it can be bolted into place, preferably above the frame. This is where the 3/8 - 16 tap came in handy. Since I had to drill mounting holes for the new tank anyway, I tapped them out with the 3/8 - 16 tap, and then started the bolts into the frame. This way, it was just a matter of lifting the strapping up over the bolts, rather than holding the strapping with one hand while trying to feed the bolt through with the other.

Tighten everything down, and remember that you may have a couple of minutes worth of fuel in the lines, and then lots of air, until you start pulling fuel from the new tank.

Eric Lusk

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