Fuel tank filler tube mod to convert 15 gallon tank to 19 gallon

Steve Rodgers

TJ Enthusiast
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Mar 25, 2018
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Maui, Hawaii, USA
i thought I saw this but lost track.
I think I want to make my 97 TJ SE tank into a 19 gallon tank by cutting the filler tube. Does anyone have a before and after photo of the mod?
It's always easier to see what the desired end result looks like.
Thank you
 
Every single article I've seen about it online is missing the photos due to them not being properly hosted.

Supposedly it's very easy, and just involves cutting this piece:

fuelmod.jpg


I'd be surprised if you really had a 15 gallon tank though. Only the most stripped down models came with them, usually the ones that didn't even have A/C!

If you end up doing this mod, it would be awesome if you could take some pictures of what you had to do. I say that because we need a good write-up detailing how to do this, since there isn't one out there I can find, not even on YouTube!
 
My 99 has a 15gal tank and I would LOVE to increase its capacity. I read about this that the tank is actually 19 but the extended the vent down into the tank so that the pump will shut off at 15gal. Apparently you only have to cut the vent tube. Is this correct??
 
My 99 has a 15gal tank and I would LOVE to increase its capacity. I read about this that the tank is actually 19 but the extended the vent down into the tank so that the pump will shut off at 15gal. Apparently you only have to cut the vent tube. Is this correct??
That's the idea. But I thought that by 1999, all the tanks were the full 19 gallons.
 
That's the idea. But I thought that by 1999, all the tanks were the full 19 gallons.

Mine isnt, the build sheet says 15.x and when the low fuel light kicks on it'll hold about 12 gallons. Also, it does have a/c but aside from that it's fairly stripped down with no cruise control, base stereo stuff, manual door locks and windows.
 
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In reply to the suggestion by Chris: "it would be awesome if you could take some pictures of what you had to do. I say that because we need a good write-up detailing how to do this, since there isn't one out there I can find, not even on YouTube!"

First, here is a picture of my gas tank, dropped from my 1998 Wrangler SE. If you enlarge this you can read that it is part no. 52018687AB, what Jeep lists as the 15-gallon tank.

20190521_154238.jpg


The picture also shows the two tubes: the thicker fuel filler tube and the thinner vent tube. Next is a picture of the inside of this tank, showing where the two tubes come in.

20190521_145952.jpg


As many have said, you only need to cut off the thinner vent tube protruding inside the tank, not the thicker fuel filler tube. You do this by feel, since you cannot see inside the tank. The easiest way to do this is with a "PVC Cutter." This also makes a very smooth cut.

20190521_154450.jpg


For those who are inexperienced, or mechanically challenged, or both (like me), it may be necessary to figure out the PVC Cutter. They are available from Home Depot for under $10, and from Harbor Freight for $7.50. They are all made in China, so it doesn't matter which one you get. They come with the blade closed, with no button to open it, and no instructions. As I learned from YouTube, you have to pull apart the two handles to open the blade. Then reach inside the tank with it, place it up against the side of the tank and around the vent tube that you want to cut, and start squeezing the two handles together to ratchet it closed. The first couple ratchetings are not cutting anything, then it engages the tube and cuts it easily like butter. As can be seen in the above picture, it leaves about 1/4 inch of the vent tube still protruding inside the tank. This cuts off about four and a half inches of vent tube, which can be seen along with the PVC Cutter in the picture below.

20190521_153721.jpg
 
According to my build sheet, my jeep was pretty bare bones. Steel wheels, no AC. It does have a 19 gal tank though
 
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According to my build sheet, my jeep was pretty bare bones. Steel wheels, no AC. It does have a 19 gal tank though
Mine shows the same, and its bare except for the AC. Lists 19 gallon tank in the build sheet.

However, I've driven it to the line at empty and when I filled up it took 15.x gallons. Unless I have another 60 miles or so (4 gallons) past E, I'm guessing it's got the long tube.

Confusing to my small brain.
 
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Mine shows the same, and its bare except for the AC. Lists 19 gallon tank in the build sheet.

However, I've driven it to the line at empty and when I filled up it took 15.x gallons. Unless I have another 60 miles or so (4 gallons) past E, I'm guessing it's got the long tube.

Confusing to my small brain.
If you read above, the guy with the 15 gallon tank has the same small brain problem and he could only get 12 gallons in his. You do have about 60 more miles of fuel left. Carry a spare fuel jug with you someday and find out. You'll be surprised and then you won't be because you'll know.
 
Wouldn't the ball in the filler tube float up and close the filler tube regardless of vent tube length? I thought that was the purpose of that ball. Or is that a heavy ball and is the roll over safety? Both seem to make sense to this small brain.
 
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When the needle is at the bottom of the E there is about 2 gallons remaining.
Not necessarily, the fuel gauge sender's accuracy is way too variable to assume anything about how much gas is left. I go mostly by my odometer and use the fuel gauge only as a rough estimate.

X2 to the above comments saying that the 15 gallon take is extremely rare. Most of those who think they have a 15 gallon tank are doing so due to the gauge being so inaccurate which is common. I thought the same thing on my TJ too when I first got it. Only the most stripped down models came with the 15 gallon tank, the rest of them came with a 19 gallon tank.

And even when the build sheet says 15 gallon tank, it will usually include the 19 gallon tank elsewhere in one of the upgrades like A/C or other upgrades. My '97 TJ's window sticker said 15 gallon tank which shocked me until I read further and found the upgrade to the 19 gallon tank mentioned inside a package further down the list items.
 
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It turns out that I did not keep the fuel tank that I modified, after seeing some damage to the tank in two places. But this is a plus for this thread, since it allows a clear comparison between the two fuel tanks that Jeep offered on 1997-1999 Wranglers. Yesterday I went to FN Jeep in Colorado Springs and bought a stock 19-gallon fuel tank from a 1998 4.0L. It is part no. 52018768AB, what Jeep lists as the 19-gallon tank. You can see the part number in this photo:

20190525_121718.jpg


The vent tube on the inside extends only a short way into the tank, as this photo shows.

20190525_121639.jpg


You can also see that the fuel filler tube is considerably shorter than the one on the 15-gallon tank. Here is another picture from the 19-gallon tank, showing this part better.

20190525_121554.jpg


FN Jeep also had a 15-gallon tank from a 1998 Wrangler, like the one that came with my 1998 SE, pictured in my previous post. According to The 1999 Jeep Wrangler Owner's Manual (I found a physical copy), the 15-gallon tank still came standard on 4-cylinder models in 1999, like it did on the 1997-1998 4-cylinder models. Here is a picture of the inside of the 1998 Wrangler 15-gallon tank that FN Jeep has.

20190525_115426.jpg


To be clear, both tanks are identical in size. Both have a 19-gallon actual capacity. The so-called 15-gallon tank only has a longer fuel filler tube and a longer vent tube, preventing more than a 15-gallon capacity.
 
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For the record, here are photos of the two tanks, showing that they are identical in size. The 19-gallon tank from a 1998 six-cylinder TJ, part no. 52018768AB, is the black one that we scrubbed clean. The so-called 15-gallon tank from my 1998 four-cylinder TJ, part no. 52018687AB, is the still dirty one that is black underneath the dirt.

20190602_175604.jpg


20190602_175812.jpg


20190602_180021.jpg
 
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Questions about the fuel pumps in the two tanks have also arisen. As far as I know, they are identical except for the gas gauge float mechanism that tells the gas gauge that the tank is full at something under 15 gallons or something under 19 gallons. Those who have kept their 15-gallon fuel pump after making the modification to 19-gallon tank capacity report that it just shows full a lot longer.

The fuel pumps themselves are identical in size. I measured the height of my old 15-gallon fuel pump and the new Delphi FG1353 19-gallon one that I bought. The photo below is a bit misleading, because of the filter on the bottom of the new one and the electrical cord wrapped around the top of the new one, and the new one being a little closer to the camera, but they are the same height.

97890


The close-up photo of the old one shows TJ15 on the gas gauge float mechanism.

20190521_153954.jpg


A new Delphi 15-gallon fuel pump costs $60 more than a Delphi 19-gallon one from RockAuto. There is no need to buy the 15-gallon one.

The RockAuto website says that the Delphi fuel pumps are made in the U.S.A., but when you get it, the box says made in China. Yes, even Delphi now.

By the way, my old 15-gallon original equipment fuel pump was still working fine. I only replaced it because I had the tank off the Jeep and the Jeep has 157,000 miles on it.