Gravity feed transfer tank
 

From a programming standpoint (logic, debugging, testing, QA, etc) that's not a good idea. What happens when you (or someone) hits the button/switch and there's not enough room in the tank? Since the flow rate reduces as the transfer tank empties, are you planning on doing the calculation of volume per second through different size filler tubes and pressures?

Your best bet is to install something like your bathroom toilet has. Fluid flows in until the float closes the supply. Even propane tanks use this technology to prevent over-filling. Looks like it's also wildly used on commercial underground fuel tanks where they are gravity fed from the trucks.

Here's a link to something that's halfway affordable:
http://www.fueldump.co.uk/products/A...ion-Valve.html

This kit is designed for constant flow and will not overfill the OEM tank. I bought an aux tank and this kit but haven't installed it.


https://www.northerntool.com/shop/to...earch=#3490901

If you have a normally closed selenoid valve you can power it through a switch and from a key-on power supply. When you turn the truck off the selenoid-valave will shut. If you are driving and want the selenoid-valve off, turn the switch off. That should be all that you need. If you want a timer, you'll need to search websites like Grainger and look for a 12 volt timer of som kind. Remember though, the RDS kit has a built in floating ball-valve shut-off and a shut-off valve at the aux tank. I personally bought a normally closed selenoid-valve for my set-up in case for some reason I need to shut it off while I'm driving but I would not hessitate installing the kit without the selenoid-valave. The kit has a shut-off valve at the tank in case the floating ball-valve were to fail.

You can never be too safe.

I can't argue with that.

I use these at work. We mount them in control panels, but I’m sure you can figure something out. The nice thing is it’s easily adjustable in respect to how much time, and they can be set up for either a normal open or closed valve

https://www.alliedelec.com/idec-corp...2d12/70172620/

I have a similar set up. I have a 40 gallon auxiliary fuel tank in the bed of the truck. A hose goes down to the OEM filler neck.
At the filler neck, there is a device which stops the flow of fuel from auxiliary tank when the OEM tank gets full.. I think it is a ball or something that floats up to block the fuel line.
In the bed of the truck, I have a manual on/off valve. I fill the aux tank with the valve off. When the OEM tank is low, and the truck is parked in the garage, I open the valve. Before I drive away, I close the valve. All OEM guages, computers etc. work normally because I simply filled the tank.
Sometimes I will have the valve open, with fuel flowing, while driving, but rarely.
This has worked for me for 7 years.

Cheers,

Ive been doing this for the past 20 years (multiple trucks) with just a small ball valve in the outlet of the aux tank.

Basically, I remove the factory filler neck and braise an 1/4 inch bung (can make by cutting 1/4 union in half) to the outlet a few inches down from the fuel cap. I then mount a spin-on fuel filter (I use a Bosch filter from a VW rabbit) under the bed.

I normally use as much of the stock fuel tank as practical before turning on the ball valve. I have found that with 60 gallons in the aux tank, and the stock tank almost empty when I turn the valve on, the stock tank will start refilling (with finely filtered fuel) very quickly due to the head pressure created by the aux tank (.4 psi per foot) which is more than enough to push fuel through the filter quicker than the engine can burn it. If I am continuing towing my camper (12.5 to 13 MPG) the stock tank will not quite fill all the way up before the trucks fuel gauge starts to drop (it gets almost full), As long as I keep driving, the truck uses the fuel at a rate that it wont overfill the stock tank.But I have stopped and forgotten to turn the valve off before and fuel did not run out the stock tank overflow (check valve in overflow fitting prevents it).

I have an electric valve I plan to install someday for a little piece of mind regarding overflow safety. Plan is to connect it through a switch wired to power only with engine ON.


BTW - my current truck is an 03 7.3 CCSB Lariat, which gives me a range of 1100 plus miles towing my 12K 5er. Last year I had a 2016 CCLB 6.7 Platnum and could get 1000 miles, and that truck held 5 more gallons than the trusty 7.3 (one of the reasons Im back to driving the 7.3 that I bought new.

I have been running this setup in the 7.3 since it was new. I ALWAYS fill the aux tank (even if I am not filling the stock tank) because of the filter set-up. This gives me the benefit of "pre-filtering" my diesel fuel before it goes into the trucks tank. This means that the stock filter of the 7.3 stays much cleaner/last longer, and the HEUI systems gets only ultra-clean fuel (I have never found anything in the stock filter bowl).

The Bosch filters from the VW application are very good filters and the elements are inexpensive. To use this set-up you can get a filter base from a rabbit diesel and the proper fittings, or get the filter from an 85 to 86 gold or jetta and just connect it to your hose (its not a spin-on, and costs more). The spin-on is best (easiest) in the long haul, but it takes more effort/parts up front to hook it up because the threads are straight metric (not pipe), so you have to find metric fittings to make it work .

I'll see if i can dig up some photos

I have been looking into this idea for a while now. I'd like to set something up with an electronic solenoid or pump at the bottom of a tank instead of a manual valve. I like the Kit from northern tool, now to find a "reasonable" priced 15 or 20 gal fuel tank HA.

12 volt valves are easy to come by. To me the pump set-up is overkill (and not as reliable as gravity (natures pump).