CJ5 dual tank pictures?

I am thinking about doing the dual tank conversion on my CJ5. I have searched the forums and the threads I have found with links with pictures are no longer active. I read a few of the threads and it seems the 15 gallon tank is a better because of ground clearance. My plan is to use a electric fuel pump to send fuel from the rear tank to the tank under the seat. I also would like to know how the filler neck is run for the rear tank?

 

http://boyink.com/cj6/gas-tank-installing-rear/

And https://www.google.com/search?q=early+CJ-5+rear+gas+tank+install LMGTFY

 

What you are describing is exactly what I did last year. I built a custom tank and plumbed it tot the original tank. Two problems that I have found are:
1) I made my tank as big as I could fit in the space under the bed. So big that it was a total pain to actually mount it.
2) The transfer from one tank to another tends to aerate the fuel. This has repercussions in hot weather, making boiling the fuel and vapor lock occur more easily.

There are some photos here: http://www.earlycj5.net/forums/showthread.php?93838-Finally-Got-Going-on-My-60-Build/page5

Other than that, I am very happy with the addition of the the extra tank. No more jerry cans for me!

 

For transfer flow applications, you will need to rig a transfer cut off switch so that you do not overfill the front tank. An electric fuel pump and pressure regulator on the rail, in-line between the front tank and engine should help to minimize vapor lock issues.

On my Landcruiser I have an 44 gal. aux. tank that is plumbed to the injector pump in parallel with the factory tank. It is essentially a parallel fuel system. There is a switched valve at the engine that switches fuel line feeds, turns on the elec. pump on the aux tank and switches the fuel gauge input from the factory tank sensor to the aux. tank sensor. All this is from a dash mounted rocker switch that is has a LED indicator that is lit when the aux tank feed is active. Probably overkill, but I do not need to worry about a busted fuel line or fuel pump failure.

 

I'd suggest you use a 3-way valve to switch between the tanks, rather than to try to transfer fuel from one tank to the other. Your mechanical fuel pump can easily pull gas from a rear tank. When I had this setup on my CJ-5, I would run the front tank dry, then reach down and move the valve handle (mounted in the floor in front of the driver's seat) before the engine quit. Easy to set up something like this.

There are also electric switches available (what my J20 has), and you can switch both the tank and the fuel gauge with one flip of a DPDT toggle. But the brass valve is the easiest to plumb if you don't have a fuel return line.



http://www.ebay.com/itm/FUEL-VALVE-...AY/181314974704?rt=nc&_trksid=p2047675.m18516 - one of many sources.

 

Mine has a 15 gal tank installed in the back. I can post pictures when I get home tonight. The filler neck hoses are readily available, but the actual filler neck isn't, so I just found a junkyard part and made it work.

 

Another thought... on my Landcruiser both tanks fill from a single filler neck with a Y pipe. There is a plunger that switches a flap valve to select which tank receives the fuel. I have also seen this on older Ford diesel trucks. Might be a cleaner and easier solution than adding another filler neck?

 

FYSA: I have 2 tanks with a 3 way valve on my 1971 CJ5 V-6. I had to disconnect the fuel return line to the rear tank, because when I used the under seat tank the fuel would be returned to the rear tank causing it to overflow. I've had it this way for over 4 years, and have had no problems not having the fuel return line.

 

You don't need the fuel return, but it might be nice to have. Circulating the fuel from the tank to the engine and back keeps the fuel in the lines cool, and helps to prevent vapor lock.

The electric valve has six connections, and switches your return line too. A while back I searched for a 6-way brass valve and found one eventually, but it was wildly expensive. Much cheaper to mount two 3-way valves and switch them both.

This is the usual electric valve - look on RockAuto for other brands. http://www.ebay.com/itm/Standard-FV...1995-Chevy-GMC-Dodge-Ford-Truck-/310870688401

 

IIRC, I have the Pollak switch installed in my Landcruiser. Been working well for about 13-14 years. Only one minor service issue. There is a diagram on eBay showing the flow and wiring configuration.

 

Ok thanks for the information my CJ5 still has the draw bar on the back. I didn't know it would have to be removed but that would make sense to make room for the tank. I think I'm going to stick with the jerry can for right now till I make up my mind if I want to have duel tanks.

 

You don't have to remove the drawbar...you have to get the 71-75 style that leaves room for the tank.












Filler neck came off a Ford Ranger-I'm sure there's many other junkyard finds that would work as well.

 

Great info!

 

Ok thanks do any brackets on the drawbar have to be removed? Because in one of the pictures it looks like you had to make new brackets?

 

Ok I see the rear cross bars on the frame have to be removed so the tank can be installed.

 

The drawbar braces that run outside the frame are factory 71-75 pieces.
I cut the stock braces off mine and bolted those on.
The frame requires removal of 2 diagonal braces that run from behind the upper drawbar area to the crossmember behind the axle. Again, stock Jeeps 71-75 were made this way-there doesn't seem to be any problems caused by their removal.

 

IIRC the military Jeeps had a pintle hook with the bumperettes and no draw bar. So the diagonal braces likely derive from that app. With the draw bar, you should not need them.

 

You have air? Go after the welds and/or rivets with a die grinder and carbide bit. That would be the tidiest way.

I'm sure you could cut it out with a sawzall, but you'd need to remove enough so that the tank fits up there. Leaving a little metal behind would not matter otherwise.

Cutoff disk or grinding disk in an air or electric grinder would also work.

Carbon arc is another option - http://www.youtube.com/watch?v=ZX4pE4KhHI8

In any case, you want to avoid removing frame metal, even if you leave a little brace metal behind.

 

A WAG? Half the tank or more. Depends on your rate of fuel consumption. The return line would not be very effective if the flow of fuel were not significant. Whatever the fuel pump can deliver in volume, minus the fuel consumed, limited by the flow resistance in the return line and filter, should be returned to the tank.