OEM Sub Tank or Aux Fuel Tank setups - For FAQ

Discussion in '80-Series Tech' started by Romer, Apr 19, 2007.

  1. Romer

    Romer fatherofdaughterofromer Moderator

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    Location:
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    The following is an item for the FAQ on tanks I put together while researching and installing my tank. There was a lot of information out there, but still a few questions that weren't answered. I wanted this to be an encompassing item using George's write-up (link below) as the starting point. Feel free to point out corrections, clarifications or add other methods, other tanks or just show us your setup.


    One of the popular modifications these days is to add more fuel capability. Additional fuel means more range.

    There are several choices to choose from depending on what you want. There are several things to consider when making this choice:

    1. How much range do you want. There is the 13 Gallon OEM sub tank and there is the 24 Gallon, 38 Gallon, and 44 Gallon Auxiliary tanks.
    2. Clearance - The 13 Gallon OEM Sub Tank tucks up above where the spare tire goes and provides no clearance issues. The 44 Gallon drops down below the rear and does impact clearance. I know a few who have smacked their 44 gallon tank on the rocks. The 24 Gallon provides a nice compromise.
    3. Modifications to allow tank. Some rear bumpers with hitches have assemblies added under the truck that require modification to allow some of these tanks. The Slee Rear Receiver brackets for towing would need to be modified to allow the 24 gallon, 38 gallon or 44 gallon tanks.
    4. Cost - The 24, 38 and 44 gallon tanks are sold new in kits and can cost over $1000 with shipping and additional odds and ends. Rarely do any of these tanks come on the market used. The 13 Gallon OEM Sub Tank can be found used for less money if your patient.
    There are 4 main components to any additional fuel tank. 1) The Tank, 2) Dual Filler Neck, 3) Transfer Pump and 4) Electronics. The electronics and Dual Filler Neck is pretty much the same for all choices. You can make your own electronics or you can order the ECU developed by George (George_TLC) in any of the applications.

    The Dual Filler Neck is one of the most difficult items to procure. As a last resort, you can get it from an Australian Toyota Dealer for about $375AU.

    The interesting thing about the 13 gallon sub tank is it is a Toyota tank designed for the 80 series. This comes installed from the factory in Australia and several other countries. However, this is not an option you can get in the US or buy parts from a local Toyota dealer. The ribs of the underside of the truck are formed to fit the tank. There is some existing wiring in the harness that can be used. There are some holes with captive nuts that can be used to install the transfer pump and the two most difficult holes to install the brackets are pre-drilled.

    [​IMG]

    George has an outstanding write-up that can be found here on installing the OEM 13 gallon Sub Tank. This write-up was used by Boston Mangler as the basis for his 44 Gallon installation and write-up. I want to thank both George and Kevin (Boston mangler) for there excellent write-ups, they helped me and others in this process.

    George's OEM Sub Tank Write-up

    Boston Mangler's 44 Gallon write-up

    I also want to thank cruiserdan, clownmidget and Cruiser804 for help they provided in this effort


    Here is an excellent write-up on a 24 gallon install

    http://forum.ih8mud.com/showthread.php?t=104791

    [​IMG]


    George's write-up is referred to in many places in this FAQ for details and pictures. It is recommended that you use his write-up as a starting place and then this FAQ and other links to augment his procedure.
    Last edited: Apr 20, 2007
  2. Romer

    Romer fatherofdaughterofromer Moderator

    Messages:
    9,465
    Location:
    Centennial, Colorado
    What I decided

    I personally did not want the 44 Gallon tank because of how far it sticks down in the back. This solution works for many individuals and is a matter of personal preference.

    I was contemplating the 24 Gallon tank. I liked the way it sat and having 24 gallons additional fuel would have been real nice.

    My main reason for getting the tank relates to when I tow my camper. Towing I get about 9MPG. When nakman (Tim Nakari) and I went to Flat Nasty in Mo., we would have to stop about 175 miles so we would not miss a gas station going across Kansas. Didn't want to get too low between gas stations. The effective range being 225miles. Adding the sub tank increases the effective range to 351 miles when towing. When I am not towing, my effective highway range is 375 and the sub tank would increase this to 585 miles. I decided that this increase in range would work for me. I could drive all the way to Moab without having to refuel when towing.

    In other words, I decided that either the 13 gallon or 24 gallon tank would work.

    The next area is cost. The 24 gallon tank would have been about $1100 and probably a bit more for other components. SOR had a 13 gallon tank with out the transfer pump and wanted $900 plus shipping.

    I spent some time searching on Australian eBay and found a tank and transfer pump set-up that would work for me. I paid $168 total to buy it and have it delivered to my door. Shipping was actually less for this tank from Australia then for one of the other tanks here in the states.

    The seller was concerned about shipping to the states and wasn't sure he could. Ozcal helped me out here by providing information to the seller on Australian Seamail. The seller took the tank to the "postal" and confirmed that he could ship it to me via seamail as it just barely fit the largest acceptable dimension when packed. This is where the patience comes in. Seamail takes 60-80 days, although I got my tank in 59 from date of shipment.

    [​IMG]

    [​IMG]

    Note: The bracket just below the tank is used to keep the spare tire in place. My spare is no longer under the truck, so I did not use it

    The next item I needed was a Dual Filler Neck. I bought it from a fellow mudder who was switching to a diesel style neck that didn't have the restrictor. The restrictor is the little plate that won't allow you to put leaded fuel in the tank.

    [​IMG]

    Note: The vent tubes on the above neck have been cut short and are usually much longer. I easily fixed this with longer hoses

    Next, a call to cdan for some misc parts (hoses, clamps) and some Rivnuts. Order George's ECU, Bought a sub tank switch from Slee (he is now out - can get them from an Australian Toyota Dealer), wire and some odds and ends from napa.


    All together, my setup cost me about $420
  3. Romer

    Romer fatherofdaughterofromer Moderator

    Messages:
    9,465
    Location:
    Centennial, Colorado
    Electronics

    The electronics for all the setups is the same if you use George's ECU. The exception is the Transfer pump depending on what you select.

    As I went through designing the harness, I used both George's and Boston Manglers write-ups to develop my Schematic schematic. My schematic is tailored for the OEM Transfer Pump. Using an additional pump is pretty easy and you can follow what Kevin did in his write-up.

    The first step is to add wires to George's ECU. I color coded the wires and notated them below so I could seal the ECU in a project box from radio Shack. I routed wires to connect to the light from the ash tray. You need to both signals to illuminate the back light. I connected power and ground like George showed in his write-up. I then took a 9 pin molex connector with the following signals:

    1. Tank Empty
    2. Tank Gauge
    3. +12V Pump/Solenoid
    These are the signals that get routed back to the tank and transfer pump. I think this is true for any tank or transfer pump you choose.

    Here is a schematic for the OEM setup courtesy of Cruiser804. Note that this is for use with the OEM ECU and has seperate signals for the pump and solinoide whereas Georges ECU uses just one.

    [​IMG]

    Here is a write-up on the switch:

    [​IMG]

    I currently don't have the gauge hooked up in the dash, but I wanted to run the wire in case I decide to do it latter. Cdan has converted a rear heater switch to switch the existing gauge between the sub tank and the main tank. Others have said they fill the sub tank and after they perform a transfer, they just consider it empty. Some also added another gauge as shown in Boston's write-up.

    I routed the harness down under the drivers side trim and used the grommet next to the rear seat under the step looking piece of plastic to get under the vehicle

    [​IMG]


    I ran 4 wires because at the time of the picture I had not decided where to tie the ground from the Transfer pump and tank. Any good ground point will do.

    The subtank wiring is as follows:
    If you want to test the empty wire before you install it:


    Below is the schematic I developed in building my harness.
    [​IMG]
    Last edited: Apr 19, 2007
  4. Romer

    Romer fatherofdaughterofromer Moderator

    Messages:
    9,465
    Location:
    Centennial, Colorado
    Using Existing Wiring

    There is wiring in the existing harness you can use and tap into rather than build your own harness. I elected to build my own as I was missing the pugtail that goes from the subtank to the existing connector on the rear crossmember.

    Here is information on how to tap into the existing harness

  5. Romer

    Romer fatherofdaughterofromer Moderator

    Messages:
    9,465
    Location:
    Centennial, Colorado
    The Tank

    One of the reasons I installed the OEM subtank is the truck was designed to fit it. Per George's write-up you will see his process on installing the Rivnuts. Of everything I had to do, this was the hardest step for me.

    You drill the two holes George shows so that you have to push hard to get the two rivnuts in.

    The Rivnuts are like molly screws. You put them in the hole and tighten the Rivnut down to compress the backside bringing the threads all the way down to the hole. The compressed material will hold the Rivnut in place.



    I talked with Cdan and he provided me the following method.

    Get bolt washer and a nut. Thread the bolt into the Rivnut in the following order: Rivnut, washer, nut, bolt. Tighten the assembly together get some spares because you will scuff this up.

    [​IMG]

    using two wrenches, hold the bottom nut in place while backing off the nut. This did not always work for me so I alternated between this and holding the bolt while tightening the bottom nut. This took me a long time per bolt and was very frustrating.

    This was much harder for the two rivnuts above the crossmember. The one that is tighter (Clearance) I was not able to get. Due to the angle I was approaching it from, I kept making the hole bigger. Note: there is a hole just under the front pass side rivnut in the crossmember, I dropped a rivnut and took a while to fish it out. I ended up covering this hole with tape until I was done.

    The subtank brackets have a hinge on one side. The hinge is on the side under the crossmember. I elected to have the one bracket welded on at the crossmember. The hinge still allows you to remove the tank. Be very careful and choose the correct bracket. The hinge assemblies are not the same and I welded the wrong bracket on. I pent 5 hours getting it back off and then welded the correct one. The longer hinge bracket goes on the drivers side.

    Put the tank in to test fit it after you get the brackets in. This makes sure you are setup correctly. Now remove the tank as it will get in the way.
  6. Romer

    Romer fatherofdaughterofromer Moderator

    Messages:
    9,465
    Location:
    Centennial, Colorado
    The Transfer Pump

    I recived the OEM transfer pump assembly with my tank.

    I installed the assembly by tightening it down with the holes with captive nuts shown in Georges write-up. These two bolts were sufficient to hold the assembly in place while I drilled the rest of the holes and installed the nuts.

    [​IMG]
    Note the hose in the pic was installed just to cap the transfer outputs. The final hose is shorter and is not hanging near the exhaust


    I then removed the transfer pump to be installed later.

    Here is some information from the OEM manual courtesy of Cruiser 804. Note this shows how to tie into the main tank directly rather than via a T into the vent tube.

    [​IMG]
  7. Romer

    Romer fatherofdaughterofromer Moderator

    Messages:
    9,465
    Location:
    Centennial, Colorado
    Installing the Dual Filler Neck

    First remove the 4 screws from the outside of the fuel cap. Begin to loosen the nut on the right side. Open up the cover for the area that holds the jack and reach the backside of the cap. There is a protective metal plate on the left side. When you loosen the nut all the way this will fall off. Loosen to the point you can take off this plate and then remove the nut.

    Remove the cover over the filler neck after you have removed the 4 screws and nut.

    [​IMG]

    Take off the protective cover on the inside of the rear fender well.

    Cut the filler tube. I made the cut just inside the drivers side frame rail. I did not remove the tube from the tank. I left it in place and it created no issues.



    Remove the old Neck.

    Place the dual filler in the cavity, it will take some work to get it in there.

    Utilize the bolt shown in Georges write-up, do not fully tighten.

    Take the black cover removed from the old neck and turn it over. You will see a circle where you will need to drill to run the knob through (I made it big enough to hold a grommet).

    Take the knob of the filler neck and fit the cap over it. Re-install the knob. Reinstall the lock mechanism (Bolt on right side) and remember to put the protective plate from the inside back on. Reinstall the 4 screws.

    [​IMG]

    Tighten the bolt holding the filler neck on.

    Now Install the hoses for the main tank using clamps to tighten down.

    Install the sub tank and connect these hoses using clamps as well

    Note: I connected the hose and connector to the tank as I was installing it as accessibility to these points later on is questionable. Make sure the are routed the way you want as the tank is put in place and bolted in.
    Last edited: Apr 19, 2007
  8. Romer

    Romer fatherofdaughterofromer Moderator

    Messages:
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    Location:
    Centennial, Colorado
    Plumbing and tyeing into the main tank

    I used the method described by George to tie in with a "T" into the main tank vent line. Accesibility is tight here and not having installed the transfer pump yet will help.
  9. Romer

    Romer fatherofdaughterofromer Moderator

    Messages:
    9,465
    Location:
    Centennial, Colorado
    Lessons Learned

    Here is my recommended order of installation after going through the process. make sure you put clamps on all the hoses.:

    1) Build Georges ECU in cab harness and install. Don't hook up the +12V Ign yet
    3) Decide on plan of action for harness (Use existing or build new harness). You can build this at any time, just don't install yet.
    2) Rivnut Install
    3) Test Fit Tank and then remove
    4) Drill holes and temp install the transfer pump. I left the pump in and it was a real pain to work tying into the main tank. Made it much harder.
    5) Cut off old filler neck just inside driver frame rail. Remove neck.
    6) Use bolt to temp fit filler neck per George's write-up. Don't tighten bolt yet.
    7) Drill hole in plastic cap on outside of filler (reuse existing) to fit pull knob and a grommet). Get the cap fitted in and bolted in. Now tighten Dual filler bolt.
    8) Install hose's to main tank from filler neck (Subtank out)
    9) Install the subtank making sure you can get at the connector and plumbing. I elected to hook up the connector and the hose as I was installing as I could see it could be problematic later on.
    10) Install dual filler to sub tank hose.
    11) install tee in main tank vent line. This will be how the tank transfers fuel to the main tank. I had to use a 1/2" tee and then a reduced after an inch of hose to match the diameters of the vent hose and the transfer pump hoses.
    12) Install Transfer pump and connect hose from tank and hose from tee
    13) Install harness
    14) Connect harness to ECU and connect +12V ign to ECU harness.
    15) Put some fuel in both tanks to check for leaks and then give it a try.


    If the setup does not work. First check the following:
    1) does the switch come on (indicator light)?
    2) Is ther 12V coming out of the ECU, at the Transfer pump connector?
    3) Is there a good ground at the ECU and transfer pump?

    I had items 1 and 2 occur to me and they were both caused by a poor ground. Once fixed the indicator light came on and the pump started humming.
  10. Romer

    Romer fatherofdaughterofromer Moderator

    Messages:
    9,465
    Location:
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    Post up your setup or provide other links that you feel should go in the FAQ on this topic.
  11. Romer

    Romer fatherofdaughterofromer Moderator

    Messages:
    9,465
    Location:
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    Make sure the tank your getting has the correct sending unit ( 3 wires)


  12. Romer

    Romer fatherofdaughterofromer Moderator

    Messages:
    9,465
    Location:
    Centennial, Colorado
    Several have incorporated the Toyota subtank roof console gauge with the fuel gauge and compass included. This requires changing out your sun visors.

    Prossett started a thread on this here

    You can also see it in Boston Manglers install thread.
  13. loquito

    loquito

    Messages:
    808
    good idea ;)
  14. 82-40

    82-40

    Messages:
    129
    Location:
    Palmdale, CA
    Is this some thing worth looking into?
    Finally a high capacity replacement tank for your FJ80/LX450 that does not require the installation of an auxiliary tank, and associated plumbing. This 38 gallon replacement fuel tank mounts where your OEM tank did originally, and re-uses the OEM sending unit, fuel pump, and filler. Made of high quality aluminized steel, and fully baffled and trapped for off-road use. :eek:

    Will not fit 1990-1992 FJ80 Land Cruiser.

    LR3880 LONG RANGE REPLACEMENT FUEL TANK FZJ80/LX450 38 GALLON CAPACITY
    $850.00 :cheers:
    Last edited: Apr 20, 2007
  15. Romer

    Romer fatherofdaughterofromer Moderator

    Messages:
    9,465
    Location:
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    Go to post one and look at the criteria. That provides additional range, but will likely impact clearance behind the rear tires. Also, I did forget to mention in the FAQ that the larger tanks will add more weight which may force you to change your springs and greater variance from empty to full. Not having one of these I have no idea the change from empty to full does. Maybe Boston Mangler can post up his experience and the weight impact between empty and full.
  16. 82-40

    82-40

    Messages:
    129
    Location:
    Palmdale, CA
    :cheers:
    Last edited: Apr 21, 2007
  17. Romer

    Romer fatherofdaughterofromer Moderator

    Messages:
    9,465
    Location:
    Centennial, Colorado
    Here is a thread on that tank.

    http://forum.ih8mud.com/showthread.php?t=73174

    If you want to get into a discussion on that tank, please start a new thread. Theis tank is a great addition to the FAQ thread and thanks for pointing it out. Feel free to come back here when you decide and post your setup, soultion or conclusion.
  18. 82-40

    82-40

    Messages:
    129
    Location:
    Palmdale, CA
    " OTHER TANKS " What part of other tanks don’t I under stand!?? That’s all I have to say about it. Thanks Romer, :cheers:
    Last edited: Apr 21, 2007
  19. Romer

    Romer fatherofdaughterofromer Moderator

    Messages:
    9,465
    Location:
    Centennial, Colorado
    Brian - no need to slip back to your corner. I think we have a mis-communication.

    I think it was great you brought that tank up and it rightly belongs here.

    You will notice there are a lot of threads going on relative to the subtank with discussions, questions and issues. Some are quite long.

    This is a thread for the FAQ, and I just was asking if we are going to get into a several page discussion to start a new thread and then come back with the results, conclusions, etc. Maybe the raeding of my tone imples something else like, don't hijack, or wrong topic. That is not the case here. This tank is a perfect addition to this FAQ. Not knowing how far you wanted to go with the discussion, I simply posted what my expectations for an FAQ thread are.

    :cheers:
  20. bigbrowndog

    bigbrowndog

    Messages:
    1,663
    Location:
    N.Q. australia
    The seller was concerned about shipping to the states and wasn't sure he could. Ozcal helped me out here by providing information to the seller on Australian Seamail. The seller took the tank to the "postal" and confirmed that he could ship it to me via seamail as it just barely fit the largest acceptable dimension when packed. This is where the patience comes in. Seamail takes 60-80 days, although I got my tank in 59 from date of shipment.

    I think you guys did well to get the tank shipped. I had problems getting a diesel injector pump shipped as I was told it was classed as dangerous goods.I finally got it brought up here privately as the big Couriers and Greyhound Bussfreight would not ship it at all. They were more definite about not shipping a diesel tank at a later date. I was told the only way to ship the tank was on an open truck. cheers.

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