dual fuel tank operation

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iapexl8r
Posts: 6
Joined: Tue Jul 03, 2018 5:46 pm

dual fuel tank operation

Post by iapexl8r »

Hey guys I am fairly new to the FSJ world, I have a 1976 Cherokee Chief that is equipt with dual tanks.I was unable to ask PO any questions about the jeep

I do have some questions about the operation of the fuel tanks. First of all what I think I know please correct me if I am wrong.
1. It is an over flow system, fuel fills from the aft tank and over flows into the fwd tank.
2. fuel seems to slosh back and forth some?? unsure of this
3. The jeep is EFI and I am pretty sure the fuel returns to one tank and not the other.

What I would like to know
is the hose that connects the two fuel tanks available for purchase
is it possible to completly fill both tanks? tried this once, was unable to completely fill the Fwd tank.
How much should each tank hold. and any other info on the system would be appriciated.

thank you
chris
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tgreese
Posts: 7118
Joined: Fri Jun 08, 2012 6:31 am
Location: Medford MA USA

Re: dual fuel tank operation

Post by tgreese »

Do you have one or two filler necks? Sounds like you have a single cap with a filler that branches. Seems like a poor design to me. Where is the second tank located? A popular add-on, but totally custom AFAIK. I suggest you give us some pictures of what you have.

There is a feed and a return line. You can use an electric valve that will switch both the feed and return. You can use a pair of manual valves and switch them both. Or you can run the return to the main tank, run the main part way down, run on the aux until empty, then switch back to the main. This works fine with a carbureted car, but it may not be great for EFI.
Last edited by tgreese on Mon Sep 03, 2018 3:04 pm, edited 1 time in total.
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weeegoneeer
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Re: dual fuel tank operation

Post by weeegoneeer »

Mine has a label saying NWMP and fits where the spare went. It fills through one neck, and gravity will keep the levels the same on both (i.e. when the gauge reads 1/4 tank, I actually have 1/4th of my gas left). There's also an electric pump in case I need to force extra gas into the main tank.

Pretty sure this is how mine works, I couldn't find any documentation but I get about 450 miles after filling it up and not using the pump. Also, like you I can't get it 100% full, usually goes to 90% or so, though I have a theory that if I sit for a few minutes the gas between the tanks would even out more and could fit more gas.

Just posting in case it helps, not sure of your setup.
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ghcoe
Posts: 1228
Joined: Sun Nov 03, 2013 6:39 am
Location: SW Idaho

Re: dual fuel tank operation

Post by ghcoe »

I just installed my extra tank. I can not see how the T would allow one tank to fill and then fill the other tank. It seems that both fill at the same time to me, but I have only filled them once. The return line from the carburetor only returns to the stock tank. I was told that you run off the rear tank until it is empty and then switch to the front tank. With the return line only returning to the stock tank it will always be full when you make the switch.

Also with my installation I am running two electric pumps. One for each tank. I put one way flow valves in the separate tank lines to keep the fuel from back flowing into the other tank depending on which pump is in operation.
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ghcoe
Posts: 1228
Joined: Sun Nov 03, 2013 6:39 am
Location: SW Idaho

Re: dual fuel tank operation

Post by ghcoe »

I just installed my extra tank. I can not see how the T would allow one tank to fill and then fill the other tank. It seems that both fill at the same time to me, but I have only filled them once. The return line from the carburetor only returns to the stock tank. I was told that you run off the rear tank until it is empty and then switch to the front tank. With the return line only returning to the stock tank it will always be full when you make the switch.

Also with my installation I am running two electric pumps. One for each tank. I put one way flow valves in the separate tank lines to keep the fuel from back flowing into the other tank depending on which pump is in operation.
SW Idaho Overlanding Facebook: https://www.facebook.com/SWIdahoOverlan ... page_panel
SW Idaho Overlanding Youtube: https://www.youtube.com/channel/UCYuRx2 ... wVwZJ5oztg
1977 Jeep Cherokee WT
All-Terrain T/A® KO2
Safari Kit
Factory Brush Guard
Factory Tire Carrier
Custom Roof Rack
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