So I took the plunge and went for the conversion of my sport 15 gal. gas tank to the 19 gal. by using these instructions on how to here: Got Trail? Rob's (AKA seRob) Jeep site
And what Happened? It worked like a charm, and took a mere 3 hours or so to do, and cost $9.99 for a new fuel pump seal! Bought mine from quadratec. MOPAR 52018808 - MOPAR® Fuel Tank Pump Seal for 97-04 Jeep® Wrangler TJ & Unlimited - Quadratec
First thing you do is take your filler ring off! Simple...The instructions I used also called for taking the rear tires off to clear up more room to work with but I didn't do that, they didn't get in the way for me.
Next, you unplug all the wires you see that lead from the gas tank and also disconnect the ground wire on top of the filler tube. As you can see here I still have the evap hose to disconnect, this one is a little tricky since the line is rusted so give it a good twist, and if it breaks off a little no big deal, just buy some tubing to patch up the connection.
Now your on to dropping that silly 15 gal. tank to the ground...Place a jack under the tank with a block of wood on top, if you don't want to scratch things up. I also used two foundation blocks to help me out.
Remove the seven nuts that hold the gas tank to the frame. I only found 6 on mine that were in tact, but o well. Once that is done work the gas tank down to the ground, keep in mind of your filler tube it is a tight fit to come through and you will have to guide it, this is where another person to help might come in handy...
Once you get that thing to the ground you will see the fuel pump and it's housing on top of the tank. Remove the white ring by using a flathead screwdriver and a hammer by chisel-ing on the grooves counter-clockwise. Make note of how the fuel pump seal is attached so you can put your new one on easy...
Now that the fuel pump is out, it's time to pick the tools you will use to cut those gay filler tubes out that are inside the tank. I did not have a razor blade or scraper handle handy like the instructions I used said, so I worked with what I had. Reach your hand inside the tank and towards the filler tubes and you will feel two different sized tubes. Cut each one about an inch away from where they come in inside the tank. Here were my tools of the trade...
I know, the one on the right is ghetto lol, but it works! And the Jeep Rescue knife did a hell of a job as well.
One tube down, 1 to go!
Another one bites the dust! There is the culprit there that causes the pump to stop at 15 gal. It creates enough pressure to push the ball up and make the pump think that your jeep is full, but you are not!
Now if you got any residue in your tank make sure you get it all out, I went ahead and dumped the remaining gas in my tank out and cleaned up the tank really good. Once that is done, you should know what to do from here to get going again! Just make sure you install a new seal on the fuel pump , don't want any leaks! Use your jack and a block of wood if needed, i'm sure using multiple jacks would be a good idea but I just have one and it worked out ok.
Feed your filler tube back through to it's spot, and put all your nuts on to hold the tank in place while you start plugging your wires and hoses back together. Once I was done, I put a few gallons of gas in it to make it to the station and filled it up here is the outcome! I was bone dry at home and I know I only put in 2 to 2 1/2 gallons if that to go to the station so I came out to it holding 19.5 to 20 gallons somewhere around there, I was very happy!
It is BY FAR one of the best mod's I have done for my jeep in the 3 months of owning it, and I advise anyone else to do the same if you are tired of only going 200 210 miles on a tank of gas and would like to use your tank to your full potential!