I'm sorry if this has been covered, if so can some one hit me up with a link?

I've seen some folks run spare fuel tanks on their roof rack and not just an extra 5 gallon can, I'm talking like a 10-15 gallon fuel tank. One I think I saw some time ago on an FJ had a set up to run a line right into the main fuel tank. Any one have a set up like this or can point me to some vendors?

Thanks for any help on this!

I've heard of doing this, but always thought it odd to put that much weight so high up. Throws your center of gravity off. Not to mention carrying that much highly flammable liquid over your head.

I've often thought it would be neat to pull the KK spare, remove the mounts and any other brackets under there and mount a second fuel tank in the hollow cavity. You might want to add a second skid plate, but overall it seems like a better idea than being all weebly-wobbly with several hundred pounds of sloshy, explosive fuel up on the roof.

For the spare tire, either plop that on the roof, fab up some kind of rear bumper tire mount that swings away to let the rear liftgate open, or use a tow hitch mounted spare carrier.

I would argue that the liquid over your head in an secure approved fuel tank is no more dangerous than under you.

Second I'm not sure what kind of fuel you are using but a gallon of gasoline usually weighs around 6.25lbs so 12 gallons would be 75lbs not "several hundred pounds". Your suggestion to put the spare tire up there means you are okay with putting around 50lbs up there so I think 75 would be okay.

I guess I overestimated how heavy 15 gallons of fuel would be. My bad.

Still, if we are talking fuel tank and not a spare fuel can/container, then we are talking a whole new level of complexity if you are planning on wiring it into your fuel system (running lines, dealing with vacuum pressure differentials and reprogramming the computer to handle the changes in sensor input, etc.) Putting it up on the roof makes it that much more complicated. Not to mention trying to fill the thing at your average gas station if you can't take it down off the roof. There may also be laws restricting the placement of hardwired fuel tanks. It may not be legal everywhere to put a "hardwired" fuel tank on the roof.

Now, if you are just talking "really big gas can that I can refuel my regular tank from" then I guess I can see that. Although lifting it up onto the roof doesn't sound like much fun. (You will have to remove it and place it on the ground to fill it if you are in the US. Safety laws and whatnot dontcha' know.) Ordinary "jerry can" style gas cans still sound easier. 4 five-gallon Jerry cans will fit nicely in a roof rack and give you a full tank refill. You can get some here: Jerry Cans

Sorry to be such a wet blanket. Maybe someone else will know more about this than I. Then we can both learn from them!

Well slap me silly. I did a bit more searching and came up with an FJ forum where they talk about just this thing:

fjcruiserforums

Interestingly, they are NOT using it hardwired into the tank. Just as a refill option using either CO2 pressure, gravity, or an electric pump. looks like they are using ordinary marine style plastic fuel tanks. Neat. Still sounds like a PITA to fill though. To each his own I guess.

Hope that helps!

Thanks WearyMan, you're not being a wet blanket, there are some very real "cons" to this set up and you are right, a few 5 gallon Jerry cans would probably be a lot easier.