Fuel tank on roof

[ducktapeguy]

I don't think gravity would work if the tank was mounted under the bed. Someone on the mud forum used to make a transfer pump with fuel sensing auto shutoff, but it seems if you were going through all that trouble it'd be better to just run a separate fuel pump in the aux tank so instead of having multiple points of failure you'd have redundancy. Having the ability to flip a switch on the dash to switch tanks is really convenient, but it depends on how often you really use the extra fuel.

No trailer I easily do 500miles in the Subaru which is why we typically are in the Subaru when we find our selves just taking roads to see where they go.

These are all tank averages at fill up.

500 miles a tank must be really nice, you must live at the top of a really long hill. I miss driving my Forester which was able to barely squeeze out 400+ miles per tank. But even with that range, I actually ran out of gas once and came very close a couple of other times while exploring the backroads of California. I've recently moved up to a GX460, and I haven't driven it long enough to get a feel for the range, but if I can get 300+ miles per tank I'd be happy, although 350+ miles would be really nice.

 

[rruff]

I would consider having a custom-made tank designed and welded up to fit right where your spare fits. Have a valve between the spare tank and the normal tank. When your tank is almost empty, someone can flip the valve and the spare tank would effectively "refill" your existing gas tank. That way you wouldn't need to worry about screwing with the fuel pump or sending unit to adjust for empty/full gauges.

Sorry for segue since I have a different vehicle.

My Tundra has a ton of empty space under the cab on the driver's side. Could I just mount a tank under there and plumb it into the existing tank? I can tuck it up to the same height, so gravity would cause fuel to flow into the main tank. I like the idea of redundancy (in case the main tank is punctured) so I'd probably put in a valve and keep it shut when offroad, unless I really need it.

 

[BurbanAZ]

Yea I'm thinking I'll get a huge transfer tank for my f350 and use that for trips where we plan on really covering a ton of miles or pulling the trailer. Then I'll save the 4Runner for trips where we want to run trails and stuff and just plan on needing to stop more often, plus without having the trailer well be getting about 15 so that'll help too.

The f350 is a diesel, long bed 4 door so it's like driving a bus off road. On the freeway though or just on really really long trips it runs great so I'll just use it for that. Also we bought the trailer for the 4Runner to pull so it's only like 3000 lbs, that'll be nothing for the f350

 

[Clutch]

Sorry for segue since I have a different vehicle.

My Tundra has a ton of empty space under the cab on the driver's side. Could I just mount a tank under there and plumb it into the existing tank? I can tuck it up to the same height, so gravity would cause fuel to flow into the main tank. I like the idea of redundancy (in case the main tank is punctured) so I'd probably put in a valve and keep it shut when offroad, unless I really need it.

Probably better off just getting the Transfer Flow 46 gallon tank they have for the Tundra, than fussing with a custom tank. Transfer Flow already has done all the figuring...


https://expeditionportal.com/transfer-flows-toyota-tundra-46-gallon-replacement-gas-tank/

 

[rruff]

Probably better off just getting the Transfer Flow 46 gallon tank they have for the Tundra, than fussing with a custom tank. Transfer Flow already has done all the figuring...

I wasn't thinking a custom tank, but something off the shelf. The Transfer Flow is much more expensive, appears to hang down farther, and doesn't provide a separate switchable source of fuel. The DC Longs like mine have loads of space under the cab that the short beds don't. Seems like an extra tank would be a good way to use it. I'd have to build support, but I don't think that would be difficult.

It doesn't seem like the plumbing for an auxiliary tank would be hard, but I don't know if any of the fancy electronics would have an issue.

 

[BurbanAZ]

I don't think a tundra tank would fit. An aux in the spare space would be the best choice to not effect handling of COG much but I worry that it'll turn into a fire in an accident. Chances of getting hit in the rear bumper are high, so I worry a tank directly behind that could be risky.

 

[Clutch]

I wasn't thinking a custom tank, but something off the shelf. The Transfer Flow is much more expensive, appears to hang down farther, and doesn't provide a separate switchable source of fuel. The DC Longs like mine have loads of space under the cab that the short beds don't. Seems like an extra tank would be a good way to use it. I'd have to build support, but I don't think that would be difficult.

It doesn't seem like the plumbing for an auxiliary tank would be hard, but I don't know if any of the fancy electronics would have an issue.

Planning on doing an electric fuel pump? As I don't think you could get the aux tank high enough for gravity fed.

That is the beauty of one big tank, no fussing with having to switch tanks.

I don't think a tundra tank would fit.

That was directed at rruf and his Tundra

An aux in the spare space would be the best choice to not effect handling of COG much but I worry that it'll turn into a fire in an accident. Chances of getting hit in the rear bumper are high, so I worry a tank directly behind that could be risky.

Yeah, six of one, half dozen the other.

Try and solve one problem, others arise.

Safest is either a swing out bumper jerry can holder, or put them on the trailer. That or ditch the 4Runner altogether, and get another platform that yields more range.

 

[rruff]

Planning on doing an electric fuel pump? As I don't think you could get the aux tank high enough for gravity fed.

There is no problem getting it as high as the current tank. The tanks are made to accommodate the shortbeds where the tank extends under the cab. Mine ends well aft of the cab. There is actually a big empty space under the bed between the tank and cab where I could put an extra tank.

 

[BurbanAZ]

Well I found a great deal on a transfer flow tank for my Ford so I bought that. With that tank we'll have around 2000 miles range if we want. With the tank back there I still have over 6 feet of bed space left. I'll use the Ford to pull the trailer and on really long trips, then use the 4Runner for the more technical stuff and just stick with using jerry cans as a little back up since I'll get better mileage with it if I'm not pulling the trailer.

 

[Clutch]

Nice!

 

[Pskhaat]

Nothing material to add, but I'm in the same Toyota existential urban-design and -bias fuel range problem. Frankly, I hated having a spare tire on a rear swing for in/out of the cargo area for long tours especially considering I utilize the 3rd row for actual people. Prefer the spare underneath.

Atop that my 2006 LC100 has the brilliance of placing the charcoal canister and evap system above where the spare is, thus not allowing for an aux tank there. Again, a brilliant Toyota design for the US market; because Toyota USA.

So I've got spare underneath and above that a critical engine component that cannot be relo'd. Thus I'm either back to a rear swing just for fuel, or...ugh...the roof. Is there really no good solution here?