98 ZJ gas tank in a 2K XJ

Rick, I have my ZJ tank, new AEM pump/filters and new regulator. Do you have the measurement of the length of the turn-up on your 1/2" copper vent extension tube.....or the gap between the top of the modified vent tube and the top of tank? I can guess-timate from the picture, but knowing how detailed that you tend to be, I thought that you might have recorded this measurement.

I did not take the time to do any measuring. The tube was cut long and installed in the tank(pointed down) and then rolled up and marked 3/8" below the high point just behind the pump.

RCP Phx said:

I did not take the time to do any measuring. The tube was cut long and installed in the tank(pointed down) and then rolled up and marked 3/8" below the high point just behind the pump.

Click to expand...

Great, thanks! I'll run with a 3/8" air gap.:thumbup:

never added the copper vent tube when swapping tanks in my 2000 XJ but i fit over 24 gallons in my ZJ tank without topping it. the tank is from a ‘95 ZJ

Following Ron's lead, I've completed my 95 ZJ Tank to 2000 XJ swap and am pleased with the results.

I used a similar vent extension as Ron and went with a 3/8" air gap as my target.
After taking some measurements, I ran a 5/8" drill bit through the tank vent nipple and reamed it out so that the 1/2" copper vent extension tube was a very snug fit.
I heated up the plastic vent nipple with a heat gun and then tapped the copper tube from inside the tank until the ends matched up at the outside lip of the nipple.
The fit was so tight that it required pliers to rotate the 90* end of the copper tubing to it's vertical position, so I'm confident that it needed no additional adhesives to keep it in place.

I cleaned the sending unit and installed the new AEM pump, new regulator and new filters, then plugging it in and tested for power and the float range to ensure that it still generated proper readings from E--F.

I installed a new sending unit gasket and found that cheap cooking spray works great for lubing up the sending unit/gasket matting surface, so that the sending unit slipped right in with a few mallet taps.

Knowing that plastic on plastic fittings are typically high friction and can be stubborn, I applied a liberal coating of silicon spray on the threads of the plastic sending unit retention nut, which made installation a breeze.

With the fill and vent hoses installed, I slipped the tank into place and installed the straps, then dumped exactly 5 gallons of fuel into the tank, primed the pump twice with two key cycles and the Jeep fired right up.

I checked for leaks and then drove 3 blocks to completely fill the tank. I noted that with 5 gallons in the tank, the fuel gauge read 1/4.

The gas pump stopped at 22.1 gallons and I slipped in a little more. Final total was 22.66 gals + 5 gallon can =27.66 gallon tank capacity. :clap:


BTW, I slotted the holes on the passenger side of the XJ tank skid and while it is a more snug fit than on the XJ tank, it does fit, shifting to the passenger side by approx 3/4".

I'm very pleased with this mod and look forward to the benefits of additional range when I drive from UT to CA next month to run the Rubicon.

Glad it worked for you! Those are almost the exact numbers I came up with. :cheers:

Ron, where did you find your tank? Did you just grab it from the junk yard?

No I got mine from ZJ friend that removes all his for a fuel cell.

I paid $125 for my ZJ tank.....only to find out later that my friend who had parted out 3 ZJ's still had all 3 tanks on hand.:doh:

Opening this back up because I have a crack in the tank. haven't got a good look at it yet but I have located a shop that does plastic welding that I plan to take it to. Should be a easy job as I had to custom trim/fit my gas tank skid when I did my SFR shackle relocation boxes.

I got the skid plate off and it has stopped leaking for now, the factory skid seems to have been applying to much pressure on the sides of the tank. I've got almost a full tank so I'm going to wait till the fuel level drops to remove the tank. In the mean time I will add a 1/2" to the overall width of the skid.

Has anybody found a good tool for the locking ring?

https://www.autozone.com/wrenches-p...vaCx4lIIMpszo2oSWlkaAo3EEALw_wcB&gclsrc=aw.ds

My buddy has something like this. I've seen other types of tools. On my zj I just used a small piece of wood, like 1"x¼" 4"s long and a hammer on the groove tapping slowly till it breaks loose and doing the same amount of turns back on. I sanded the edges first so as to not damage the locking ring. I don't recall the exact wood I used, but it was softish so as not to gouge the ring and instead took the punishment

The challlenge is trying to both hold the piece of wood and swing the hammer with only one hand.

I bought this one off Amazon for$19, it works perfectly as I removed the old pump from my original tank last night. I intend to use it until I can get my ZJ tank repaired. https://www.amazon.com/Fuel-Pump-Lock-Ring-Removal/dp/B01JY5VZZU

I used a chain wrench on the original install but I want use a torque wrench this time. Hard to believe but the FSM calls for 55ft/lbs for the lock ring!

I believe it. Seems excessive imo, but holly hell it was on there SNUG when I converted my zj to an external pump

Amazon F'ed up today and I received a 2nd lock ring tool! This one will go to work for my son's collection of odd tools.

Well today had it's up's and down's, the nipple on my original tank roll-over valve broke off installing the fuel pump(pita) and it's spun welded to the tank in 1-piece (JB Weld repair). The ZJ tank has a rubber grommet that holds the roll-over valve in place so I definitely need to get the crack fixed before my XJ tank fails in some way

Oof. Had the zj pump fail with a full tank of gas.. I actually just cut an access panel in the rear hatch and had fun that way. Still sucked. Back then, the "swampy mod" was all the rage so I bought a mustang 5.0 fuel pump an installed it inline under the frame rail just after the filter. Looking back this seems like a crazy mod to do, especially as I was just dipping my feet in the jeep world. I think I was smart enough to not send sparks with a grinder all over the top of the tank.. pretty sure I used a Dremel and tin snips. I later turned it in to an access panel that locked in place and was rubberized and had zero rattle even with my subwoofer.

Miss being young and dumb...
Now I'm just older lol

That all to say, it made dealing with the pump a brease. The original fuel pump sending unit was retained but with a length of fuel line ran through it to the bottom. As far as the roll over valve though, I'd have kept that whole and in tact.

Jb aught to cover it? although, something like that (with fumes a concern) I'd expect you (of all people) to bite the bullet and get another sending unit from the jy??
Idk, maybe gas makes me nervous these days. A fella from nagca back in the day burnt his jeep down from hot exhuast parking on dry weeds, little ember got going near the tank and it was an inferno in no time. Seeing the aftermath I'm overly careful. Welding and grinding near the tank/fuel lines I'm overly cautious with welding blankets and I have a fire extinguisher at all times on the rig.

Either way I'm sure you'll do a good job, stay safe bro