Adding Aux Fuel Tank - What should I do?

[Troop4x4]

1987 Isuzu Trooper 4x4. My range is about 200 miles with the stock tank (16 gal). Getting about 15mpg highway, 10 city. Isuzu left a gaping cavity beneath the back seats, boxed in by the drive shaft, rear axle, and carrier-bearing crossmember. Measurement show I could fit a (roughly) 9" tall, 18" wide, 26" long tank in that space. That's about 18 gallons worth of volume. I'd install a sender in the tank, and just have a toggle on my main gauge to switch between reading level in Aux and Main. I'd have an electric transfer pump that I can flip on to pump fuel from the Aux to Main as needed on long trips with no fuel stops available. Should I do this, or should I just buy a big plastic tank to strap down in the rear cargo area and set up with a transfer pump and such? That would be the cheaper option, though having a fuel tank in the cabin seems like a stupid idea to me. Advice please!

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[TDAWG]

I'd say go for it. Adding a tank to the underside sounds like a better plan than carrying a tank anywhere in your vehicle. If you add protective plates you should be all set. I know a few friends that have transfer tanks in the back of their trucks both Diesels & Gas.


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[Randy P]

1987 Isuzu Trooper 4x4. My range is about 200 miles with the stock tank (16 gal). Getting about 15mpg highway, 10 city. Isuzu left a gaping cavity beneath the back seats, boxed in by the drive shaft, rear axle, and carrier-bearing crossmember. Measurement show I could fit a (roughly) 9" tall, 18" wide, 26" long tank in that space. That's about 18 gallons worth of volume. I'd install a sender in the tank, and just have a toggle on my main gauge to switch between reading level in Aux and Main. I'd have an electric transfer pump that I can flip on to pump fuel from the Aux to Main as needed on long trips with no fuel stops available. Should I do this, or should I just buy a big plastic tank to strap down in the rear cargo area and set up with a transfer pump and such? That would be the cheaper option, though having a fuel tank in the cabin seems like a stupid idea to me. Advice please!

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Much better use of space! Im surprised no one else has thought of that already and built an off the shelf product!

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[dblack]

Tank underneath sounds like a cunnning plan to me.

I'd suggest wiring a timing relay on the pump. What seems to happen is that people turn the transfer pump on and forget it. Running the pump dry and wrecking the pump.

 

[Tim]

I'm surprised that no one has built one already either. I'm fairly sure these guys in Australia http://thelongranger.com.au/ used to do one. I had a Trooper a few years back and remember looking at them. They call them the Holden Jackaroo out there. I'd be going with an external tank as well. If you are getting one made I remember reading about having baffles in them so the fuel doesn't just rush around in the tank. How will you fill it? Just rely on overflow from main tank? I have a friend with that setup and he's having trouble getting that to work properly because his vehicle isn't always level. He found a local fuel station with a slope and that works OK!


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[GoingCommando]

I have a Jeep Commander that I'm also adding additional fuel capacity to. And I have a large space in my undercarriage one I removed the spare tire. An auxiliary tank configured to feed the engine is expensive, though. I bought 2 8-gal Aully Park tanks, and my outfitter is building brackets and a skid plate to secure them underneath. I'll have to crawl under the jeep and unscrew them to take out to refill the main tank. That won't be fun, but I'll do it one time and nearly top off my tank.
I paid $140 each for the tanks on Amazon, and paying $500 for installation. Jeep is still at the outfitter, but I'll post pics when I get it back.


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[Troop4x4]

Thank you for all the input!

As for leaving the pump on, I planned on the switch being lit with an obnoxiously bright LED (perhaps deep blue or purple) so it'd be hard to forget it's on, but I didn't think of a timer. I'll look into that.

The back seats sit on a raised floor. The tank would go under this raised floor, and I would put a filler neck on the side of the foot well. So to fill the Aux, just open the passenger side backseat door and open the cap, fill it just like a normal tank. I'll include a pic or two to show we're I'm talking about.

I'll definitely have to add heat shields around the muffler which will be right next to the Aux. thanks for the input everyone!!


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[Boort]

@Troop4x4

Can't say that I've seen one done on a trooper before, but I saw these guys write up where they yanked a tank from a 2000 Trooper and mounted it in the stock spare tire location on a Tacoma.

http://www.expeditionswest.com/equipment/tacoma/fuel_tank.html

Boort

 

[VCeXpedition]

I would take some pretty good measurements of your available area, considering driveline movement etc., then go and snoop around a pick-ur-part to see if there's not an OE gas tank in an approximate shape/size that might work. That way you could use the tank straps, filler neck parts and fuel pump and there you go!

I have a 44 gal aux tank in my '80 and I went from a 200 mile range to a 650 mile range. Game changer! I don't carry spare gerry cans outside or inside my rig.

Dan.

 

[Dana Ramos]

I have a Jeep Commander that I'm also adding additional fuel capacity to. And I have a large space in my undercarriage one I removed the spare tire. An auxiliary tank configured to feed the engine is expensive, though. I bought 2 8-gal Aully Park tanks, and my outfitter is building brackets and a skid plate to secure them underneath. I'll have to crawl under the jeep and unscrew them to take out to refill the main tank. That won't be fun, but I'll do it one time and nearly top off my tank.
I paid $140 each for the tanks on Amazon, and paying $500 for installation. Jeep is still at the outfitter, but I'll post pics when I get it back.


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Looking fwd to seeing this!

 

[Longshot270]

I'm also watching. The patriot only has a 13 gallon tank.

An alternative switch could be a push button like the starter switches and old style high beam switch. It'll take a minute or two but you'll never worry about forgetting to turn it off.

 

[GoingCommando]

Bad news. Once they got under there they decided there was not a feasible, safe way to secure the tanks that would still allow me to take them on and off. So I'm back to the drawing board. There is plenty of space under there, but I probably need to spring for a full-fledged auxiliary fuel tank. Something like this, maybe: http://www.truckinginfo.com/channel/fuel-smarts/product/detail/2013/10/auxiliary-fuel-tank-for-pickups-uses-spare-tire-s.aspx

 

[Dana Ramos]

Bad news. Once they got under there they decided there was not a feasible, safe way to secure the tanks that would still allow me to take them on and off. So I'm back to the drawing board. There is plenty of space under there, but I probably need to spring for a full-fledged auxiliary fuel tank. Something like this, maybe: http://www.truckinginfo.com/channel/fuel-smarts/product/detail/2013/10/auxiliary-fuel-tank-for-pickups-uses-spare-tire-s.aspx

Bummer but that aux tank looks cool. Looks like it would fit well in place of the spare.