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Discussion Starter #1
Does anyone know who makes an under the bed auxiliary fuel tank. I want to keep the factory tank so that the miles to empty still work and dont want to loose space in the bed. I don't mind loosing the spare. Anyone have any suggestions.


Thanks
 

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Discussion Starter #3
They make a replacement tank, but not an additional tank that mounts under the truck.
 

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flduramax,
Here is a idea, 96 Suburban's used a 46 gal tank mounted where our spare tire goes. If it would fit in our newer body, you could install the tank, put a switch in the cab for the fuel pump, and a fuel line from new tank to possibly the fuel return line or elsewhere???? Filling the new tank might be accomplished with a double filler tube at the stock fill location, I have seen one, not sure who makes it. Then once our tiny tank gets low, hit the switch and watch your gauge move to full and shut off, good for almost 2 fill-ups. Anything is possible and would be nice, besides that I have never used a spare tire in my life, and HOPE to keep it that way.Edited by: CAJUN86
 

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Discussion Starter #6
Cajun86,


That sounds like a great idea. I can't use the spare anyway, my other tires are too big.
 

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Forget the best part, it has to be wayyyyy cheaper than buying a replacement tank for approx. $800.00 + installation price. Replacement tank holds I think 45 gallons, Suburban tank way approx. 72 gallons.
 

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I looked at doing this using the aft-axle aux. tank from a chassis cab which would add only 16 gals, though, if I remember correctly. The OEM setup uses two filler necks and uses a transfer pump to move fuel from the aux tank to the main tank. There is a sending unit in each tank. If I understand it correctly, the ECM uses input from both sending units to provide your gauge with the amount of total fuel on board - counting both tanks. The ECM then activates the pump to keep the fuel in both tanks level, until the aft-axle aux tank is empty. THere are two lines between the aux. tank and the main tank. One is the fuel transfer line which is routed through the transfer pump. The second is an equalization line which allows vapor or air to flow between the tanks.


Our truck has a slot in the driver's side power center (under the hood) for a fuel pump relay. The Helms manual provides the schematic for wiring this setup, including the pins and wires you'd have to add to the ECM connectors. I did check and the chassis cab aux. tank does not simply bolt right up to the 2500HD frame. In fact, a much larger aux. tank would fit there. Perhaps the suburban tank would fit? I'm also interested in the ability to fill both tanks from one filler as where to locate the second filler was one reason I cooled on this idea.


That all being said, I don't know if the 2500HD or 3500HD ECM will support this function. I haven't gone that far but if someone were serious about doing it, it might make for an excellent setup.
 

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I think Transfer Flow makes the double filler neck that mounts in the stock location. I saw it on my friends Ford van, trying to get in touch with him to verify. I sure one could get it to fit GM, or they might make one for GM. I not too sure on your electrical wiring system, seems a little complicated. I was trying to keep it cheap and simple, and maintain our mileage computer. But if your way is possible without driver input it might be the better way. Lets keep up on this, I like the idea of 72 gallons per fill up or around 1296 miles.
Another idea would be to install an inline filter between the two tanks. A 20 or 10 micron then down to a 2 micron after the main tank, then to our perfect
OEM filter. Really one could fill the new rear tank only using the stock filler and a new hose routed to the rear tank and use the fuel pump for filling the stock tank during your rear tank fillup. Who knows?
 
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