XJ Buildup III

ZJ Fuel Tank Swap continued

New sending unit tank gasket/o-ring. This is a dealer item.



The sending unit o-ring is a very tight fit, so I slathered it with this high-tech lube that would dissolve in fuel. Worked perfectly.

The sending unit retention nut plastic on plastic friction was minimized with a liberal coating of silicone spray lube.



Sending unit assembly installed, fill and vent hoses installed with new clamps, ZJ tank assembly is ready for install.



I already owned an XJ fuel tank skid plate and I wanted to reuse it, however, the ZJ tank is about .75” wider than the XJ tank. The XJ tank skid will fit the ZJ tank with some modification to the passenger side mounting bolt holes.

I used a carbide bit on my die grinder to slot the skid holes until they lined up with the unirail bolt holes.



Modified XJ tank skid plate ready for install. The ZJ tank bolted into place using the factory XJ tank straps.



I added exactly 5 gals of fuel to the tank, fired up my Jeep and drove 2 blocks to the fuel station, where I proceeded to fill the tank. Total fuel capacity was 27.66 gallons.



The first full tank of fuel that I ran through it netted me 368 miles of range, with mixed driving conditions.

This has been a very useful mod. :thumbup:

That's always a great mod! :cheers:

It's ironic that your verbiage, photos, and results were almost identical to mine!
https://www.naxja.org/forum/showthread.php?t=1154068

RCP Phx said:

It's ironic that your verbiage, photos, and results were almost identical to mine!
https://www.naxja.org/forum/showthread.php?t=1154068

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Ironic?
I followed your lead on this mod, so thanks for doing a great job in documenting the project! :thumbup:

Glad I could help out, it's amazing what you can do with 7gals more of fuel !!!

Earlier this year, I sourced a 3D printed switch panel with 6 slots for switches and one power/accessory port, to replace my factory 3 slot switch panel.



I ordered and installed a BlueSea 1039 4.8A dual USB module and 12V power port, as well as an air compressor toggle switch. This leaves me with an open switch port for aux lighting control in the future.

The 12v power port in always hot and is the one that I plug my 120V inverter into when out exploring, and the dual USB port is switched off of the ignition.

The air compressor switch controls the underhood relay/Viair 450C compressor for activating my ARBs and tire pressure management.

I dig the fuel tank mod. After my last trip to Moab, with a friend in a Land Cruiser with a 50 gallon aftermarket tank, I really felt like I needed more range. The price of a ZJ tank vs the aftermarket 30 gallons makes this a much more attractive project.

IslanderOffRoad said:

I dig the fuel tank mod. After my last trip to Moab, with a friend in a Land Cruiser with a 50 gallon aftermarket tank, I really felt like I needed more range. The price of a ZJ tank vs the aftermarket 30 gallons makes this a much more attractive project.

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It's a great bang for the buck mod.

XJEEPER said:

It's a great bang for the buck mod.

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And I've found a tank for $50. Guess I know whats happening next.

UPDATE on the ZJ tank swap:

I took a trip to the San Juan Mountains of Colorado last month and was able to track my fuel consumption during this 1314 mile round-trip excursion.

Range with the modified ZJ fuel tank is 395 miles, averaging 15.3 MPG. Rig is set up with 4:88 gears, 295/75/16 tires, 4.0L/AW4, 6" lift, 4975 lbs loaded (4560 empty) traveling at 70mph ave @ 2850 (EDIT: 2750) rpm.

XJEEPER said:

UPDATE on the ZJ tank swap:

I took a trip to the San Juan Mountains of Colorado last month and was able to track my fuel consumption during this 1314 mile round-trip excursion.

Range with the modified ZJ fuel tank is 395 miles, averaging 15.3 MPG. Rig is set up with 4:88 gears, 295/75/16 tires, 4.0L/AW4, 6" lift, 4975 lbs loaded (4560 empty) traveling at 70mph ave @ 2850 rpm.

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This thread gives me hope of going a week without having to fill up! Great write up!


Sent from my iPhone using Tapatalk

2022 has come and gone and while I did get a fair amount of off-road time in, there were few post-worthy mods to share.

During one of my trips, I did experience a passenger main leaf failure on my 15yr old Rubicon Express 3.5" leaf pack that have been in place since my original build.


I was able to Gorilla tape the pack together and using some strategically placed ratchet straps, I limped my Jeep off the trail and back to town, where I sourced a well used factory XJ main leaf to salvage the weekend and make the 250 plus mile trip back home.
They've done some hard work in that timeframe, being airborne in the dunes more than a dozen times, countless miles of bombing down forest service roads and a myriad of sandy washes and flexed-up slickrock shenanigans. All in, over 120,000 miles of combined use.



I sourced a pair of 4" Deaver G9 leaf packs and a pair of anti-wrap perches, as the perches that are currently on my D44 were custom made for the 3.5" leafs/ 1.5" shackle combo, for a net 6" of lift. These perches will be too tall for the Deaver packs, so they will get chopped off and replaced.







Gotta get this project knocked out before the Winter 4x4 Jamboree at Sand Hollow in two weeks.

I'm happy to report that after 700+ highway miles and 3 days of wheeling desert terrain in Sand Hollow, the new Deaver's performed flawlessly. They initially netted 0.750" lift increase over my previous setup, but after 3 days of flexing my rig up in tight washes, playing in the dunes, and bombing whoops, the springs have settled to a 0.250" increase.

The trail ride is much improved, flex is great and on-road, my rig feels more stable. :thumbup:

I don't want to hijack this thread but.... are all ZJ tanks 22 gallon?? I have one out of a wrecked 97 ZJ Larado 4.0 but don't know what capacity it is. My 93 ZJ Limited 4.0 is the same as my 97 XJ sport as far as what they hold when refueling. Any info on this.

Da XJ nut said:

I don't want to hijack this thread but.... are all ZJ tanks 22 gallon?? I have one out of a wrecked 97 ZJ Larado 4.0 but don't know what capacity it is. My 93 ZJ Limited 4.0 is the same as my 97 XJ sport as far as what they hold when refueling. Any info on this.

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As I understand the ZJ tank rating, the capacity is 23 gal.

Note that some gas station fill nozzles are designed to shut off earlier than others, such as the one's at Costco, so you can't really use this method to determining actual tank capacity.

With the vent mod that I've outlined in my thread, my tank has 27.5 gal usable capacity.

XJEEPER said:

As I understand the ZJ tank rating, the capacity is 23 gal.
With the vent mod that I've outlined in my thread, my tank has 27.5 gal usable capacity.

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Yes, I get +27 gallons on a refill of a empty tank!

So with that in mind which sending unit to use, XJ or ZJ for the ZJ tank. I have both on hand and want some extra distance also with fuel prices going back up.

What hood vents are those? Do they reduce underhood temps by any significant amount?

Da XJ nut said:

So with that in mind which sending unit to use, XJ or ZJ for the ZJ tank. I have both on hand and want some extra distance also with fuel prices going back up.

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You would use one for your year XJ as they are the same dimension so you just need it to match your electrical connector.

Da XJ nut said:

So with that in mind which sending unit to use, XJ or ZJ for the ZJ tank. I have both on hand and want some extra distance also with fuel prices going back up.

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I used my XJ sending unit in the ZJ tank. I also replaced all of the filters and installed a high volume fuel pump at the same time, as it will eventually feed the 4.6 stroker that I'm building.

ZJ Fuel Tank Mod https://www.naxja.org/forum/showthread.php?t=913774&page=20