Dual fuel tank dillemma

Modified FSJ Tech Area
Post Reply
User avatar

Topic author
Tatsadasayago
Posts: 3684
Joined: Thu Aug 28, 2014 2:22 pm
Location: Sacramento, CA

Dual fuel tank dillemma

Post by Tatsadasayago » Sat Nov 01, 2014 2:53 pm

Hey guys, I could surely use some ideas on this.

My Cherokee currently has the stock 26 gallon coffin tank and an aftermarket Aero style 33 gallon tank behind the axle.
There is only the stock filler and it feeds the Aux tank then once it reaches full it allows fuel to gravity transfer to the main tank.
The venting lines feed from both tanks to a T then runs up to the stock liquid check valve. The fuel return lines are not in use but still there.

Here's a quickie diagram of my setup below.

Image

Green shows the modified filler hose and re-routed extension.
Red shows the aux tank.
Blue shows the transfer hose linking the tanks together.

I located a 74 filler hose, extension and elbows to revert everything back to stock...sort of.
My existing filler hose appears to be a Cali only 77 version or one from a later model as it is all metal, about 1" diamter and has a metal vent line coming off the top that runs alongside the filler tube. It has that annoying spring loaded flap and as I've said before, will spit fuel back immediately if I try to fill with the pump nozzle even 1/2 way to the first click on the lever.

So, I have pondered this for a long time and have a few ideas and would like your opinions:

Plan A: Drop the aux tank completely and add the stock pieces back.

Plan B: Leave both tanks and just add the better filler neck so I can at least pump fuel somewhat normally.

Plan C: Keep both tanks, replace the filler neck, eliminate the balance hose and add another filler tube somewhere.

I like the idea of having a backup tank with say, 10 gallons in it, but having to completely fill the rear tank before the main even gets a drop bugs me. Often the fuel will go bad before I use it up and hauling around 60 some gallons of fuel all the time won't do MPG any good. The bonus of having the aux tank is if I top off in Reno, I can drive to Montana with only one fuel stop in Salmon, Idaho or so. Kinda handy in the event of a zombie apocalypse or an extended drive around the desert dodging mutants without worrying about running out of gas.....but I digress.

I did ponder a single filler neck and adding a Y valve of some sort too but didn't know where to look for a gasoline rated one.

OK, there you have it. What would you do in my place?
1977 Cherokee Chief - The Blair Jeep Project III
A collection of parts flying in close formation

User avatar

Stuka
Site Admin
Posts: 10524
Joined: Thu May 12, 2011 5:53 pm
Location: Sonora, CA
Contact:

Re: Dual fuel tank dillemma

Post by Stuka » Sat Nov 01, 2014 3:13 pm

The correct way to do this type of tank setup is to have a filler for each tank, and then have a switch to swap between the primary and secondary tanks. Much like 70's GM's were setup.

BTW: Your stock tank is 21 gallon.

However if it were me, I would ditch the coffin tank entirely. They suck. I ran out of gas I don't know how many times in my Cherokee because I was driving down a hill with less than half a tank. The pickup is in back, and its so long you can get into a case where it sucks air because all the fuel is up front.
2017 JKU Rubicon Lifted and stuff
Pevious Jeeps: 1981 J10, 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ

User avatar

Topic author
Tatsadasayago
Posts: 3684
Joined: Thu Aug 28, 2014 2:22 pm
Location: Sacramento, CA

Re: Dual fuel tank dillemma

Post by Tatsadasayago » Sat Nov 01, 2014 6:40 pm

Thanks for the correction. For some reason I had 26g in my mind. Good point about the coffin. I don't think I've ever had that experience but can see it happening.
Thanks for your input!
1977 Cherokee Chief - The Blair Jeep Project III
A collection of parts flying in close formation

User avatar

jaber
Vendor
Posts: 3022
Joined: Sat Aug 27, 2011 5:24 pm
Location: Chino Valley, Az.

Re: Dual fuel tank dillemma

Post by jaber » Sat Nov 01, 2014 8:07 pm

My 77 J10 had a spare tank setup with a PVC Y connecting the fills together. Standard drain PVC will do just fine. If your not comfortable with that, hit an exhaust shop and and have one made.

a dumbass on a smartphone...
Jeff

'46 cj3a
'51 Willys p/u
'51 Willys Parkway Conversion
'74 CJ5
'75 J-20 Wrecker
'75 J-20 Cummins service truck
'77 J-10 p/u
'79 Cherokee
'88 Grand Wagoneer
http://s252.photobucket.com/albums/hh14/jeffaber/

User avatar

berettajeep
Posts: 293
Joined: Tue Nov 26, 2013 5:07 pm
Location: Astoria OR

Re: Dual fuel tank dillemma

Post by berettajeep » Sat Nov 01, 2014 8:17 pm

I also have dual tanks with only one filler on my '74. Mine splits right after the filler into both tanks and I have a splitter switch on the floor under the drivers seat that does not work.
Plus I have a few vent/return lines that are disconnected in the back. I just filled my tank for the first time 2 weeks ago and near the end of filling it, fuel poured out one of those lines... :oops: It looks some what professional by hacks. :lol: :banghead:

I am dreading dropping both tanks to replace lines/ reconnect lines but know I need too.
'47 CJ2A My build
'74 Cherokee S 401/auto My build
'94 Cherokee 4.0 5 speed
'06 Liberty Renegade
'46 CJ2A

User avatar

tgreese
Posts: 4732
Joined: Fri Jun 08, 2012 6:31 am
Location: Medford MA USA

Re: Dual fuel tank dillemma

Post by tgreese » Sun Nov 02, 2014 8:29 am

My J20 has dual tanks with separate fillers and an electric switch for the tank feed and return lines. That's what I'd suggest.

I would not use PVC or ABS or any other plastic plumbing pipe for filler neck plumbing. I believe you can use polypropylene in contact with fuel, but it's not rigid enough. And I don't know where to source it ... IMO it would be easier and safer to get a piece of exhaust tubing bent to shape.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 FCA Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.

User avatar

Topic author
Tatsadasayago
Posts: 3684
Joined: Thu Aug 28, 2014 2:22 pm
Location: Sacramento, CA

Re: Dual fuel tank dillemma

Post by Tatsadasayago » Sun Nov 02, 2014 11:11 am

Thanks for the advice guys.
I think pulling the main and plumbing the aux tank properly is the best bet. I've been looking at a swinging fuel pickup and an electric pump as well.
Getting rid of the tank switches, wiring and extra fuel, return and vent lines will clean things up as well.

Again, thanks for the input!
1977 Cherokee Chief - The Blair Jeep Project III
A collection of parts flying in close formation


BugsInMyTeeth
Posts: 44
Joined: Thu Apr 17, 2014 10:44 pm
Location: Apache Junction, AZ

Re: Dual fuel tank dillemma

Post by BugsInMyTeeth » Sun Nov 02, 2014 7:12 pm

I'm going with your option C. This is what mine will look like from the outside when I'm done. With a proper selector switch, supply and return lines.

Image
Image

Using this switch
http://www.summitracing.com/parts/smp-fv5k

And these Waggy parts
Image

I'll be putting it here;
Image

I haven't got my hands on the stock fill neck-to-tank plumbing yet but that should be pretty cut n dry. I need to pick up a four inch hole saw(thought I already had one), and I gotta find my dang ol pop rivet kit...

I'll do a full write-up on it in a dedicated thread in a week or two.
Real good at going slow.

Bugs

'64 Wag - Grampa
'87 Wag - Pinky
'79 Wag - Lucky


letank
Posts: 3406
Joined: Wed Oct 03, 2012 9:16 pm
Location: SF bay area

Re: Dual fuel tank dillemma

Post by letank » Wed Nov 05, 2014 11:23 am

BugsInMyTeeth wrote:
And these Waggy parts
Image
Also working on the same idea, tired of the flapper inside the 74, it took sometime to gather the 80's filler neck and bits. The 74 filler is plastic. Then I found a later 70's metal tank with the right fittings for the 80's filler. Then muffler shop for the long pieces.

The 74 tank has a metal dam across the tank next to the pick up hose, so the fuel does not slosh all the way to the nose, forgot to check if the replacement late 70's has it too.

Is that summit fuel switch for 5/16" hose?
Michel
74 wag (349 Kmiles... parked, next step is a rust free body)
85 Gwag (227 Kmiles... the running test lab)
See Engine bits , Fuel and brake lines, Body work, Trany and TC


BugsInMyTeeth
Posts: 44
Joined: Thu Apr 17, 2014 10:44 pm
Location: Apache Junction, AZ

Re: Dual fuel tank dillemma

Post by BugsInMyTeeth » Wed Nov 05, 2014 5:33 pm

letank wrote:Is that summit fuel switch for 5/16" hose?
I made a call to Summit to be sure. They said it's a 3/8 supply and a 5/16 return... hmmm.

edit: I found this, http://eaccess.smpcorp.com/eCatalogs/Do ... -726-1.pdf
Last edited by BugsInMyTeeth on Thu Nov 06, 2014 4:21 am, edited 1 time in total.
Real good at going slow.

Bugs

'64 Wag - Grampa
'87 Wag - Pinky
'79 Wag - Lucky

User avatar

Gumby
Posts: 1426
Joined: Sun Jan 29, 2012 10:20 am
Location: Tucson, AZ

Re: Dual fuel tank dillemma

Post by Gumby » Wed Nov 05, 2014 8:11 pm

Well thanks for bringing this issue up folks, I just picked up a tank to do this mod. So I'll be paying close attention to this tread.
1984 GW 360/727/208.... 4"/ 31"
2004 CRD QC SRW 3500 4X4 (DD)
1983 "project Dubya" (long term)


Matty1
Posts: 2
Joined: Sat May 29, 2021 6:44 am
Location: TX

Re: Dual fuel tank dillemma

Post by Matty1 » Mon Jun 07, 2021 5:18 am

WARNING! Stop with the saving money or trying to on tasks like this!
The j10 and J20's I'd throw a boxed tank in the bed, run the line to the oem tank, triple your range and call it a day. The OEM are usually 18. Any old amc engine is going to drink that like a 22 year old at Beerfest in Germany.
Dump the OEM tank and install a larger capacity tank for your Cherokee's Waggoneers and what have you. There is enough space under our old boats to fit almost anything.

User avatar

Stuka
Site Admin
Posts: 10524
Joined: Thu May 12, 2011 5:53 pm
Location: Sonora, CA
Contact:

Re: Dual fuel tank dillemma

Post by Stuka » Mon Jun 07, 2021 10:04 am

Matty1 wrote:
Mon Jun 07, 2021 5:18 am
WARNING! Stop with the saving money or trying to on tasks like this!
The j10 and J20's I'd throw a boxed tank in the bed, run the line to the oem tank, triple your range and call it a day. The OEM are usually 18. Any old amc engine is going to drink that like a 22 year old at Beerfest in Germany.
Dump the OEM tank and install a larger capacity tank for your Cherokee's Waggoneers and what have you. There is enough space under our old boats to fit almost anything.
This thread is SEVEN years old. Really no reason to bring it back from the dead.
2017 JKU Rubicon Lifted and stuff
Pevious Jeeps: 1981 J10, 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ

Post Reply

Who is online

Users browsing this forum: No registered users and 2 guests