2016 Ram 3500 auxiliary fuel tank plumbing??

[ivbinconned]

I have traded off my 06 Ram cummins for a 2016.
I have a tank in box with filtered line to main tank. I can leave the valve open and fill both tanks and there has been no leaking.
Can I do same with this 2016??

[FireRob]

My 2016 does not even have a gas cap. I was concerned as well but that quickly went away. Most of the time my auxiliary fuel take valve is left open all the time. All I can say is it works and I love having the tank and extra fuel on hand.

[Grit_dog]

So, reading the other slip tank thread, it appears that there is a check valve in the tee in the filler hose. Makes a lot more sense than relying on the fuel tank vent check valve and the gas cap or whatever seal is in the capless systems.

[Grit_dog]

Are you really able to fill the primary tank with any efficiency through the slip tank ?
I'd think an average gas pump could fill the slip tank before 30 or so gallons gets into the OE tank.

[Grit_dog]

Thank you for explaining that.
I know the OE fuel tank vents have a check valve on them for rollovers and such.
So the gravity feed system puts that check valve and the fuel filler cap into active duty?
While I believe it works obviously, Im not fond of parts so easily removed like a gas cap being the only thing keeping 90 gal of fuel from spilling.

[ivbinconned]

Sorry Grit. For taking so long to look here again. The fuel cap in the 06 does not leak with the head of fuel above it. I ran all fuel through slip tank so that it was pre filtered to the main. The main fills and air/fumes escape through a valve on it. When fluid reaches the top it must have a floating ball in the breather that prevents fuel leaking.

[Grit_dog]

So how does this work.
Looks like these " drip"systems don't have any thing keeping the fuel back from over filling the factory tank. Fluid level in slip tank is higher than the fuel cap on the truck. Is it only the fuel cap on the truck keeping a spill from happening? It actually has a head pressure of fuel against it ?
Or is there a check valve on the upstream side of the tee into the filler hose on the vehicle?

[FireRob]

Same as post above. Valve gets left open all the time and no problems so far in the last seven or eight months I've had it.

[MSGTRETIREDCSP]

I had my 91 gallon tank installed in my 2016 RAM. It's gravity fed into the filler tube. I've had no over flow so far. I had some overflow problems in my old 2008 F-350.