Anyone know of a custom fuel tank that goes under the driver and passenger seats (similar to MAF's) for a FJ40? I would like to avoid the problems others have had with the one from MAF due to the location of the fuel pickup in the tank (causes fuel starvation in off-camber situations).

Have not had any luck with local fabricators. All I want is to get rid of the aux rear tank and still have more than the 18 gals the stock tank holds - my built 383 is NOT fuel efficient.

Any ideas appreciated.

TIA....

Bruce in Redding, CA

I'LL BE MAKING MY TANK SOMEDAY WHEN I GET TO THAT POINT, AND FIGURE OUT WHERE I CAN PUT IT WITHOUT COMPROMISING CAMPING GEAR SPACE. I'M THINKING THE SUMP WILL HAVE A SET OF PLATES, LIKE A 4 SIDED PYRAMID WITH THE TOP HALF CUT OFF, DIRECTLY OVER THE SUMP, BUT MISSING THE FRONT SIDE OF THIS "PYRAMID", SO THAT AT LEVEL SITUATIONS, THIS FUEL WILL BE COVING THIS, BUT IN STEEP CLIMBS AND OFF CMABER SITATIONS, THE 2 SIDE AND ONE REAR PLATE WILL TRAP FUEL IN THE SUMP...

I'LL ALSO ADD I KNOW NOTHING ABOUT WELL DESIGNED INTERIORS OF FUEL TANKS. IF ANYONE WANTS TO CRITISIZE THAT DESIGN, LET IT FLY!

JUST WONDERING, WHY ARE YOU NIXXING THAT AUXILARY TANK?

MATT

Originally posted by FIXXXXAH

I'LL ALSO ADD I KNOW NOTHING ABOUT WELL DESIGNED INTERIORS OF FUEL TANKS. IF ANYONE WANTS TO CRITISIZE THAT DESIGN, LET IT FLY!

JUST WONDERING, WHY ARE YOU NIXXING THAT AUXILARY TANK?

MATT

I'm looking into a custom tank for under the custom roll cage I got from Ryan! I'm going to run a nice baffled aux tank in the rear (thanks to Matt aka Bentmetalworks!!) and feed that from a custom tank under the seats. Hopefully in the 20 gal range (for 42+ total).

I don't know much about tank design either, but sounds like the "baffle" set up you're talking about make work!! My custom tank would have to be about 2-2.5 inches shallower than the stock tank, so off camber really concerned me!!

I'm also interested in hearing ideas from others!! Fuel cell in the back behind the seats is not an option. My 3 yellow labs took a vote!!:D

one thing to remember, if you make an actual "sump" , you may have problems down the line with dirt/water/ect. cumulating there. the better solution would be a simple cylinder shape around the pick-up with a few small holes at the bottom, enough to let the fuel stir and mix, but slow it down when off camber.
there is a product, (dont have info) out there which is a small pressure tank of sorts that is plumbed in-line with the fuel line kinda like a filter. anyway it has a one way valve so that when you loose fuel to the pick-up the "pressure" in the can supplies fuel to the engine, i think its a crossover from airplane industry.

If you can design it, this guy can build it and he is certified. If you are serious I can talk to him. However, it is the same with any business, 1 tank will be a fortune, a few will be expensive, a large order will be reasonable.

Stainless steel would be way cool:D http://www.trailquest.com/tanks.shtml

I am in the prosess of doing a fuel tank for my FJ 40, as well as being certified in welding, I plan to build one from Aluminum that will go between the frame rails just behind the front seats, I will include a 2 or 3 inch body lift for clearance, but I haven't decided weather a series of baffles is best, or just using foam sticks like the circle track fuel cells have. Any suggestions would be appreciated. Oh, and I plan to install a stock in tank fuel pump for my EFI system, with an access pannel in the floor.

DOES ANYONE HAVE A GOOD LINK TO A TANK SITE, MORE EXPLAINING GOOD BAFFLING AND USE OF FOAM, LESS TRYING TO SELL A TANK? RHINO, DONT YOU THINK THE VILOLENCE OF ROCK CRAWLING THROWING THE FUEL AROUND WOULD MIX THINGS UP?I PLAN TO RUN A BURLY FUEL FILTER, SO IM NOT too WORRIED ABOUT SEDIMENT. DID YOU EVER GET MY PM ON YOUR 2" BS RIMS?

DAVE- I NEGATED A TANK THERE DUE TO THE BODY CLEARANCE PROBLEMS. I THINK MY TANK WILL GO BASICALL IN THE STOCK LOCATION, POSSIBLY A SADDLE STYLE CROSSING TO THE DRIVERS SIDE AS WELL. DO YO HAVE ANY INFO ON THE CELL FOAM? THANKS, MATT

Hey Matt,
With the body lift and the 4"SOA, I should have plenty of room to put it under the body, as for the foam sticks, check speedway or JAZ. they will both have it for about 2.50 a stick approx 3x3x12" I think, it just stacks in the tank from top to bottom,

DAVE- YEH, IM NOT BIG ON BODY LIFTS ;) HOW MUCH FOAM DO YOU PUT IN THE TANKS?

i havent seen much in the way pf fuel tank building on the web, the problem i hear with the foam is that it brakes down over time, typically one season, but i have no experience with it.
baffles are the way to go, but how many or hole size i couldnt tell ya, as for crawling shaking things up, i supposes it would do that well enough to keep sediment from collecting in a sump.
pm on bs wheels?? musta been a while ago, i'm sure i would've answered it. remind me what it was about.

I built my rear bed mounted tank earlier this year. It fits flush with the top of the wheal wells and has a 5gal sump that goes through the floor only 8", where the fuel pick up is. (34 total usable gal.) Here are a few things I came up to make my system work. I used 14 gage sheet metal for the outer wall and 18 gage for the inner baffles. The baffles are set in a "V" over the top of the sump with only .25" open space at the top and bottom. This forces fuel to flow through the sump prior to getting to the other side. I put the fuel return line right next to the pick up, thus creating a cross flow of fuel to clear any debris in the tank from clogging the pick up. The key thing to making the tank work off road is two fuel pumps and the secondary "header tank". This comes from model helicopters and works outstanding. There is a small half quart size tank that is completely sealed, mounted near my high pressure fuel pump. This little tank has four fittings, the first is "fuel in" from a low pressure pump drawing fuel from the main tank. The second is the pick up (fuel out) for the high pressure pump, at the lowest part of the header tank. The third is the return from the fuel injected engine. Last is the "fuel return" to the main tank located at the top of the header tank.

What this gives you is constant fuel regardless of what angle you rig is, and helps keep the baffle system simple inside the main tank. This set up would work for non EFI engines by simply by eliminating the return line from the motor. Just use a basic electric fuel pump to feed the header tank and your mechanical pump to feed the motor. However you will need a return line to the main tank. This set up works outstanding. I will never go back to a simple line from the main tank!

Here is a basic drawing of a header tank. The blue tube's represent the ports, the red part is the main body. I welded mine up from a piece of 3x3 box 3/16 wall about 8" tall. I used the thicker size to allow for directly taping the ports for the nipples for the lines to attach to.

The foam will last several years before needing to be replaced, and you completely fill your fuel tank or cell with it, it's surprizing it wont take away much volume at all, but it works very well for baffeling. I like the second tank idea, I will try to incorperate that into my system.

There is some one up close to you building custom tanks and ect. Its Percival Fab. they built the type of tank your looking for but you had better have DEEP pockets. I've heard that their Aux fuel tank that runs under the drivers and passengers is selling for $900.00 :eek: without seat mounts they are extra. Heres there # 707-678-1882

Also you might want to think of "flop tubes" for a fuel pickup. Basically the flop tube will "flop" to the lowest place in the fuel tank.

An example can be found on a homebuilt aircraft fuel tank (http://www.rvproject.com/20020627.html) Admitted we don't need INVERTED operation, but should give you an idea.

For fuel injected conversions, the "intank" pumps usually sit in a little cup to insure constant fuel to the fuel pickup.

Baffle designs work for race cars as you hit high g-force corners, but you are only there for a few moments. :) For off camber, there is enough fuel leak back... that after minutes of sitting off camber, with a low, tank you fuel runs away from the fuel pickup.

Personally I just TRY to keep the tank above 1/2 full. '79 (tank under floor) design, and it doesn't like running low when climbing. Might have picked up some junk, but do I hate stalling on a hill!

Tom :usa:

I heard a good source of custom tank builders was a back of a four wheeler. You might want to poke around, find a couple and check out their sites. Here is a link to someone who built a custom vegetable oil fuel tank for a Ford Van: http://www.veggiepower.org.uk/page402a.htm (the heaters are for the veggie oil), I think it can be fabricated easy enough, just take lots of measurements and your time and make sure you have good, consistent, leakproof welds. I'm planning on running a dual fuel systems similar to the link, but I'll probably be building my tank out of aluminum, doesn't rust!