Adding an auxillary fuel tank, how to advice needed.

I want to increase my trucks fuel capacityby 10 gallons.
I going to bolt an aftermarket fuel cell into my truck bed and mount an auxiliary switch into my dash. When one tank gets low, flip the toggle to aux to run off my secondary tank.
My superduty F250 had this setup and i loved it.
What parts would i need, and how would i set it up?

 

@colinb17 has a tank in his bed, something i wanna do someday, check out his setup

 

I've got essentially what you are talking about. only difference is that it is a lot easier to dump the fuel from the 2nd tank into the factory tank, vs running directly off of the 2nd tank.

I have a 15 gallon tank in the bed. when I flip the switch in the cab, the fuel gets pumped into the factory tank.

dual pumps to speed up the transfer, as well as act as backup should one pump fail.


the two small pump lines tee into a single larger line


that large line then splices into the filler neck of the factory tank.




installed


tank fits right between the wheel wells, under my toolbox


link to the tank

$483 Moeller Marine 031818, Topside Fuel Tank 15 Gallon, 57 Liter

https://www.amazon.com/Moeller-Boat...fuel+tank&qid=1452279578&ref_=sr_1_37&sr=8-37


overall:
-no fuel leaks
-roughly 25 minutes to transfer all 15 gallons to the factory tank
-unless you install a ball valve between the two tanks, and close it when not in use, you risk throwing a code. because the tank introduces do much more volume to the system, the truck thinks that there is a vapor leak "loose gas cap". a hand valve will solve this. I personally don't care about the light on my dash, and have left it alone.
-on road trips, your bladder will be your limiting factor for stops, not your fuel capacity.

Hope this helps

 

I looked into doing this in a hot rod that I was planning to use for cross country road trips. I spoke to Aeromotive and basically you need a second fuel system - tank, pump, return line, etc. There are valves and relays available for marine applications for this. The second tank would need to hold a pump with a similar flow rate and pressure rating as the factory unit. It would need it's own return line and could tee into the factory feed line. a 2-way back flow valve would serve as this tee - when pump one was one, no fuel could back flow into tank two, and visa versa. There would also need to be a valve to determine which return line was in use to avoid overflowing a tank. It was doable, and not conceptually too difficult, but all the valves and lines got expensive, and the complexity added failure points. Of course, this was for a 1960's car, not a computer controlled modern truck. I imagine you would need a second fuel level gauge that could talk to the computer, and I bet you would end up with codes being thrown. A better solution for our Taco's would be a larger replacement tank that uses the factory pump and sending unit, but I haven't been able to find one that isn't a one-off custom job for big bucks. I think the reserve tank being used to fill the factory tank is a better option at this point.

 

I would love to use something like this, but basically have it for emergencies. I want it to be simple and basically act as a large Jerry can. Could you use a hand pump or siphon to pump directly into the tank instead?

 

There are bed boxes with built in tanks in them that can use a hand pump or electric set-up.

Here's one example, but by no means the only one out there: https://www.transferflow.com/fuel-tanks/toolbox-tank-combos

 

Oh yeah, I've seen those. I'm trying to keep the price low though.

 

Awesome @colinb17

 

It seems for the price of Jerry cans you could get that 12 gallon tank for $77.

 

you could certainly siphon it into the factory tank, if you have the aux tank in the bed. all you would have to do is have a way to prime it

 

I've seen a few different kits on Amazon for fairly cheap.

 

That is an excellent solution, thank you!
I embrace the "KISS" concept with enthusiasm!

 

Great write up, will likely be doing this to my current truck, as well as, the next one I purchase for long trips.

I was looking for a bit more range though so I was wondering if you think id be able to use think 24 gal tank alternatively. Its made by the same company and has the same connections as yours. Any thoughts would be appreciated

$478 Moeller 031526, Topside Fuel Tank, 24 Gallon, 91 Liter

https://www.amazon.com/Moeller-Boat...-1&keywords=Moeller+Boating+Topside+Fuel+Tank

Edit: I guess my question would be, would you be able to turn on the switch in the cab and pump about half of the fuel into the tank and then turn it off and save the rest for down the road since our trucks obviously wouldnt hold it all at once?

 

Thats a lot of weight and a lot of range especially for a 4cyl PreRunner. What's your goal? Are you trying to do tha Elcan Highway?

 

Considering doimg this myself, the setup above would add 168lbs ( 144# gas, 22# tank) , not unlike having a passenger riding along

 

Really cool set up. I bet if you threw a one-way check valve in there, just before the T into the filler neck you wouldn't throw any codes, and wouldn't have to manually close a valve

 

that would probably work. the other option is an electric globe valve, that's wired into the fuel pumps. when you turn on the fuel pumps, the same switch opens the globe. turn the bumps off, and the globe closes.

 

any valve needs to be able to handle a vacuum draw, this is how the vehicle ECM checks for "leaks"

sit and listen to your truck after it shuts down, it is never truly OFF, there are pressure sensors in the evaporative emissions that watch the fuel system for leaks, there is a vacuum pump that runs at prescribed intervals that keeps the system under vacuum. this happens constantly, or until the battery dies.

the point is to keep vapors from exiting the vehicles fuel system.

 

I like the idea of electric pumps and valve, but if you'd like cheap, a simple siphon tube qualifies.

$19 The Original Safety Siphon 6 Foot Hose For Gasoline And More - 1/2" Valve Siphon Pump - Use for Cars, Boats, Mowers - Self Priming Pump Transfers 3.5 Gallons per Minute - FDA Food Grade for Home Brews

https://www.amazon.com/Safety-Sipho...Siphon+-+Safe+Multi-Purpose+Self+Priming+Pump