Auxiliary Gas Tank in Bed

[Tumbleweed]

Well I've read a bunch of threads about folks wanting an auxiliary gas tank in the bed of their truck. While numerous options exist for the diesel crowd, none seem to exist for the gassers. I used to have a 54 gallon tank in my diesel dually. Loved the extra range and the option of buying fuel where and when I wanted, rather than when I needed to.
So, I bought a 60 gallon RDS tank, 71212 56" Length x 13" Width x 19.25" Height Rectangular Auxiliary/Transfer Fuel Tank, from Amazon. I had it in my "Wish List" and when the price dropped $145, I pulled the trigger.

I mounted it offset to the passenger side so I would have more room for a valve and fittings.
I routed the vent hose to a tee I installed in the OEM vent line so there would be no fumes lingering around. I then welded a tube to allow the aux tank to gravity feed into the OEM tank's fill tube. I added an inline gas filter between the aux tank and the OEM fill tube.
It has been a couple weeks and only one small problem so far. Once the OEM tank is full the gravity fed gas will drain into the OEM vent line. This has caused the truck to stall 3 times. My solution for now is to only open the valve when I need the gas and shut it off once the factory tank is full. There seems to be no long-term ill effects of the excess gas draining into the vent line.



A little tube cutter took care of the vent line.



The tank is secured via the mounting tabs. The ratchet strap is just for a little extra security.
I do wish that the **** was welded at the rear of the tank to allow for easier plumbing, more room for fittings.

 

[AFMoulton]

So you gravity feed into your gas tank? Do you just open the valve when the factory tank gets low then keep driving?

I’m planning to add an aux tank to mine, but have an electric pump to aid the fill process.

Would love to see how you have it plumbed and how it all works. Thanks


2018 2500 6.4 4x4 4.10 Amsoil SS 0w-40, Softopper
Black Rhino Armory 18x9 +12mm
Cooper St MAXX LT295/70R18

2016 Durango 5.7 AWD 3.07 Amsoil SS 4 Qts 5W-30 and 3 Qts 0W-40
1996 Nissan Altima 2.4 Amsoil SS 5W-30

 

[Tumbleweed]

Yes, gravity fed. It's easy to open or close the valve, just step on the running board and reach over the bed side.

I've just driven it around town since I installed it. OEM tank was about 1/2 full when I opened the valve, sitting in my driveway. A couple hours later I went out and checked for leaks. Removed the factory gas cap, you could see gas near the top of the fill tube. Apparently, it only filled up to where the vent tube entered the fill tube.

The vent hose on top of the Aux tank is plumbed into the tee on the small vent tube. The main drain hose at the bottom of the aux tank is routed to the small tube going into the fill tube, shown in the pic as unwelded.

I have since changed the drain hose where it connects to the tank to a 90* elbow, pointing directly down into the hole in the bed that I drilled.


You can see how cramped the area near the tank **** is. I will likely have another **** welded to the side near the back of the tank to allow for easier plumbing and less jamming everything into place.

 

[Rado]

Tumbleweed did you use Teflon Tape on the valve threads ? If so most Teflon Tape will break down when used on petroleum ! Just something you should check on the tape label! FYI it will take time to break down so no need to over worry I have seen it used alot over the years in the heating business with no real bad effect, Just maybe some tiny seepage over time!

 

[Tumbleweed]

Good to know about the Teflon tape.
I did use some type of Teflon tape from Car Quest auto parts store.

I will verify when I get the **** welded in the rear and re-plumbed.
Do you have an appropriate thread sealing tape/compound to use?

 

[AFMoulton]

Ok, that all makes sense, so you added a metal tube to hook the rubber fill hose to on the full neck, I’m assuming it’s the unpainted metal tube in the first picture you posted?


2018 2500 6.4 4x4 4.10 Amsoil SS 0w-40, Softopper
Black Rhino Armory 18x9 +12mm
Cooper St MAXX LT295/70R18

2016 Durango 5.7 AWD 3.07 Amsoil SS 4 Qts 5W-30 and 3 Qts 0W-40
1996 Nissan Altima 2.4 Amsoil SS 5W-30

 

[Tumbleweed]

Ok, that all makes sense, so you added a metal tube to hook the rubber fill hose to on the full neck, I’m assuming it’s the unpainted metal tube in the first picture you posted?

Yes, the unpainted tube is a fuel line I bought. I cut it to size and inserted it into a hole I drilled into the OEM fill tube. Then I welded the new short tube to the fill tube.

 

[tjfdesmo]

That beats having to fill every 150-180 miles when pulling heavy!

 

[AFMoulton]

Yes, the unpainted tube is a fuel line I bought. I cut it to size and inserted it into a hole I drilled into the OEM fill tube. Then I welded the new short tube to the fill tube.

Awesome! Now just to figure out how to weld! LoL. Have you tried to use the gravity feed part as you drive?


2018 2500 6.4 4x4 4.10 Amsoil SS 0w-40, Softopper
Black Rhino Armory 18x9 +12mm
Cooper St MAXX LT295/70R18

2016 Durango 5.7 AWD 3.07 Amsoil SS 4 Qts 5W-30 and 3 Qts 0W-40
1996 Nissan Altima 2.4 Amsoil SS 5W-30

 

[SyN]

This is definitely on my list of mods - in the future!
Definitely looking @ the gravity feed design.
(Been looking @ a design on e-trailer)

Ideal for owners who tow & avoid smaller area fuel stops & can pass them by for the larger truck stops on down the road.

Thanks TW for sharing.

I am going to incorporate a (simple) small inline filter just after the valve in a spot that's easy to service. Still looking at these as well.

 

[Tumbleweed]

Awesome! Now just to figure out how to weld! LoL. Have you tried to use the gravity feed part as you drive?

I have used the gravity feed as I drive. You can watch the "Range" value increase. And the fuel gauge rise. However, I only drive 6 miles to work one way, so there is not a lot of gas getting burned.
The aux tank is meant for long road trips and I don't have any planned in the near future. I only got about 7.5 mpg when last pulling my enclosed trailer with my Jeep inside. Hunting for a place to fuel every 200 miles was not a good plan to me.

When the aux tank gets emptied and washed out, I will get a new **** installed. I really like the fact that this has a gauge on top and the included locking fuel cap is extremely HD.

 

[AFMoulton]

Awesome thanks for the input!


2018 2500 6.4 4x4 4.10 Amsoil SS 0w-40, Softopper
Black Rhino Armory 18x9 +12mm
Cooper St MAXX LT295/70R18

2016 Durango 5.7 AWD 3.07 Amsoil SS 4 Qts 5W-30 and 3 Qts 0W-40
1996 Nissan Altima 2.4 Amsoil SS 5W-30

 

[AFMoulton]

Awesome thanks for the input!


2018 2500 6.4 4x4 4.10 Amsoil SS 0w-40, Softopper
Black Rhino Armory 18x9 +12mm
Cooper St MAXX LT295/70R18

2016 Durango 5.7 AWD 3.07 Amsoil SS 4 Qts 5W-30 and 3 Qts 0W-40
1996 Nissan Altima 2.4 Amsoil SS 5W-30

 

[Bldrinker]

Link for the tank on amazon?

Is this it? They marked it down to $145?

 

[Tumbleweed]

That is the tank I bought. I did not pay any shipping. I got it for $574.11 plus tax. Amazon.com Services, Inc was the seller. The price was reduced by $145 from when I put it in my wish list several months ago. Sometimes the online pictures change. Mine has a fuel gauge and a HD locking gas cap. It does NOT include a nozzle and hose, like you would find at a gas station.

 

[AFMoulton]

If it’s not too much to ask, could you snap a pic from the underside of the filler neck? If you can see it without removing anything? Thank you for this! It’s really something I’ve been back and forth on.

I have an empty 18 gallon fuel tank sitting around that I’ve wanted to add to my 2500, but just couldn’t figure out how, without using an electric pump to pump into the tank as I sit on the side of the road. This seems way easier! Just burn the onboard tank down then stop open valve and take off again!

The 31 gal tank is a pain in the ass when pulling heavy!


2018 2500 6.4 4x4 4.10 Amsoil SS 0w-40, Softopper
Black Rhino Armory 18x9 +12mm
Cooper St MAXX LT295/70R18

2016 Durango 5.7 AWD 3.07 Amsoil SS 4 Qts 5W-30 and 3 Qts 0W-40
1996 Nissan Altima 2.4 Amsoil SS 5W-30

 

[Tumbleweed]

I don't have access to the truck right now. Here is the underside before I started. Just imagine the added short tube, tee and hoses.
My truck has the factory wheel well liners. I had to remove the driver's side. I did not remove the tire, but that would give you a little more room to work.
There are 3 Torx screws that hold the gas cap fill end to the bed. You don't need to remove the gas cap. There is a ground wire to be removed at the frame. The vent tube has a connector, just slide the white and blue pieces away from the tube to disconnect it. Then a single hose clamp at the end of the fill tube at the gas tank and the entire fill tube comes off.

 

[Tumbleweed]

The aux tank is grounded through the mounting bolts.
The fill tube is grounded through the ground wire to the frame.
I don't think there will be any issues with static discharges.

 

[Tumbleweed]

These are my weights, so I know what you mean about hauling heavy. Trailer axles are 5500 lb rated. Load Range F tires.
This scale ticket is without the 500+/- lbs. of the aux tank & gas.

 

[EastTN]

I have used the gravity feed as I drive. You can watch the "Range" value increase. And the fuel gauge rise. However, I only drive 6 miles to work one way, so there is not a lot of gas getting burned.
The aux tank is meant for long road trips and I don't have any planned in the near future. I only got about 7.5 mpg when last pulling my enclosed trailer with my Jeep inside. Hunting for a place to fuel every 200 miles was not a good plan to me.
View attachment 168998
When the aux tank gets emptied and washed out, I will get a new **** installed. I really like the fact that this has a gauge on top and the included locking fuel cap is extremely HD.

I read one of the reviews state it’s illegal to use gravity feed from the aux tank. Is this true? I imagine the danger of fuel leaking from the feed line from the aux tank to the main tank is the reason...safety. Using a transfer pump wouldn’t be difficult to install, or would it?