# aux tanks



## laknox (Apr 4, 2007)

I have a 2002 GMC Sierra 2500 HD Duramax 4x4 crew cab and tow a Komfort 25FSG 5th wheel.  Stock fuel tank is 25 gallons and that doesn't give me a whole lot of range so want to add an aux tank in the bed.  Ideally, I would like something that is fairly easy to remove as I just don't need the extra capacity all the time and can use the room when not towing.  I've decided on a 30-40 gallon tank; now, I need to figure out the best method of fuel transfer.  I've talked to several people and have basically narrowed it down to an electric transfer pump that you manually turn on and off when you need to refill the main tank.  The other method that I've seen is to gravity-feed from the aux to the main.  Northern Tool has a kit that you put in line on the filler neck of the main tank to do this.  One of my uncles has used both methods and liked both.  The main down side that I can see with the gravity-feed method is that it seems to be pretty permanent whereas the electric transfer system can be easily plugged off and the tank removed when not needed.  Any ideas, opinions, criticisms?  Many thanks.

Lyle Knox
Chandler AZ


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## TexasClodhopper (Apr 4, 2007)

Re: aux tanks

Well, the way I see it, you would have to stop for fuel anyway.  Stopping to fill your own tank from your own tank wouldn't be much different.  I'd go with the electric pump and make it all one easy to remove tank.

I used to put auxillary tanks into commercial vehicles.  We added another factory fuel switch, and the trucks just drew from whatever tank was switched in.  Disconnecting the fuel line to the auxillary tank was easy compared to taking the tank out of the truck.

You'll have to watch you weight, and consider what COULD happen in an accident so you don't become liable for what the tank does.


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## Grandview Trailer Sa (Apr 4, 2007)

Re: aux tanks

I have two trucks, one has a 115 gallon tank and the other has a 60 gal with a tool box on top.  I use the gravity feed on both vehicles.  I used to use a transfer switch that changed where the truck pulled fuel from.  No electric motor.  

I like the gravity feed much better.  Much less modifications to the truck.  With the transfer switch, I had to cut the fuel line and the return line, plumb in the switch and run wires to the dash board and mount a toggle switch.  Lots of work.


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## laknox (Apr 4, 2007)

Re: aux tanks



> TexasClodhopper - 4/4/2007  3:19 PM
> 
> Well, the way I see it, you would have to stop for fuel anyway.  Stopping to fill your own tank from your own tank wouldn't be much different.  I'd go with the electric pump and make it all one easy to remove tank.
> 
> ...



I wan't referring to a transfer tank like you'd see a farmer or construction truck have, but one that is plumbed directly to the fuel tank so you can refill on the fly.

Thanks,
Lyle


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## laknox (Apr 5, 2007)

Re: aux tanks



> Grandview Trailer Sa - 4/4/2007  3:37 PM
> 
> I have two trucks, one has a 115 gallon tank and the other has a 60 gal with a tool box on top.  I use the gravity feed on both vehicles.  I used to use a transfer switch that changed where the truck pulled fuel from.  No electric motor.
> 
> I like the gravity feed much better.  Much less modifications to the truck.  With the transfer switch, I had to cut the fuel line and the return line, plumb in the switch and run wires to the dash board and mount a toggle switch.  Lots of work.



I guess I just need to find out more about how the gravity-feed kit works.  It =is= the more elegant solution, with no moving parts; I'm just concerned about taking the tank out when not needed and what needs to be done to return the truck to "normal" usage.

Thanks,
Lyle


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## Grandview Trailer Sa (Apr 5, 2007)

Re: aux tanks

I can have my tanks out in about 20 minutes.  I don't make it a habit though.  To install the gravity feed, you have to tap into the filler hose to the main tank.  To remove, I get a piece of exhaust pipe that fits the hose and splice it in.  With that you are back to original.


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## laknox (Apr 5, 2007)

Re: aux tanks



> Grandview Trailer Sa - 4/5/2007  8:41 AM
> 
> I can have my tanks out in about 20 minutes.  I don't make it a habit though.  To install the gravity feed, you have to tap into the filler hose to the main tank.  To remove, I get a piece of exhaust pipe that fits the hose and splice it in.  With that you are back to original.



Hmmm, I figured that you could just leave the adapter in place and plug off the feed line on the filler neck when you remove the tank.  Another question, how do you keep the lower tank from overflowing?  Do you replace the cap with an un-vented, sealed cap?

Thanks again.
Lyle


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## Grandview Trailer Sa (Apr 5, 2007)

Re: aux tanks

Well, you could do just that.  I have not taken them out, just to take them out.  When the main tank fills, it is just full, does not leak.


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## adeltaman (Apr 10, 2007)

Re: aux tanks

Lyle,  I think you may be referring to the same unit that Northern Tool offers to transfer fuel from an aux tank mounted above the OEM tank.  I believe the way it controlls the the overflow problem is in the way the transfer line is fed into the OEM filler neck.  Sort of like the cutoff mechanism used in the gas station nozzle cutoff.  See the diagram in the latest Northern Tool catelog on page 180 or go on line to NorthernTool.com and search on the Diesel Install Kit for Auxiliary Fuel Tank.  Hope this helps.  I'm considering using this method when I install my aux tank.
Gordon


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