I have a homemade aux tank I have been working on.

To plumb it into the main tank, I made my own version of the RDS kit, only I welded the fittings into the stock fill pipe. I am using the same exact roll over valve they use.

http://www.northerntool.com/webapp/w...5501_200315501

"Designed to connect your auxiliary diesel fuel tank to your trucks fuel fill hose. Provides consistent gravity feed of fuel. Automatically controls the fuel level going into your OEM tank so that it does not overfill."


Now I was wondering if anyone understands how the RDS kit works? The overflow valve does not turn off the in flow (barb side) when the output side (thread side) is full according to my testing, which is against that statment from Northern Tools.

I filled the fill pipe with water to leak test it and tested the valve by blowing into the input side of the valve. As I expected I could blow into it, indicating to me that fuel would also flow. I'm not sure what the purpose of the roll over valve is?

The only thing it will do is stop fuel from passing from the "out" side to the in side when it is turned upside down... hence rollover valve.


Oh, if anyone is wondering, the stock fill cap is seemes to be sealed, or at least designed that fuel can't come out. I leak tested the fill pipe by putting the cap on and filling the other end with water. Even with me blowing into the pipe to add pressure it doesn't leak anything.

 

All i did with my aux tank was plumb in a electric valve, so when my main tank gets down to approx 1/4 left i flip the switch on and it starts filling the main tank, gravity feed, and approx 20 -30 mins later my main tank is full and i switch the valve off again. I tried running my without the electric valve, but it didnt work, it would overfill the main tank and then run on the ground,, at least the way i did it, I can shut it off and know it cant overfill.

$20.00 valve and welded my own adapter to the metal oferflow pipe and has been working now for 3 years and no problems

 

I was under the impression the rollover valve is on the top of the RDS. To prevent spill in a rollover.

There is a writeup with pictures by FiverBob I think that is recently near top of forum. Look at that.

 

Yes there is one on the top acting as the vent. I put one on the top of my tank as well.

But the install kit they sell is simply an aluminum tube with grooves cut on the ends to make it a barb and a bung welded in the middle. In that bung goes another rollover valve, same as the one on the tank.



I'm not 100% my setup is going to work, was thinking about it at work today. I ran the vent of the tank to the vent line on the main tank, figuring if it would leak, it'd go in the tank and not on the ground.

But if the diesel in the main tank is full up to the cap because the aux tank keeps it that full... I'm not sure the vent will work.
Guess I will find out!

 

Ok I got all the stuff hooked up last night. I don't have the tank in the truck, but I filled the main tank through the line that will connect to the aux tank using a funnel and a fuel jug.

As expected, the RDS setup is crap and doesn't do what it's supposed to. Big surpise there consider the "quality" of there stuff

I filled the main tank until the fuel was close to the filler neck top and then started filling from the aux tank line. I put in about 2 gallons. Cracked the fill cap and sure enough diesel poured out.

Eventually diesel started pouring out of the rollover valve on the top of the main tank as well.

 

So I'm now scratching my head to figure out how to plumb this setup.

It's obvious I need to tie the main tanks rollover valve to something

On my aux tank, I have 1 fitting for a roll over valve and the fuel cap is non-venting. Anyone have an idea how to plumb this?