Wanted to post this in case it can help someone out there. Took our 2015 31ul out for the first time this last week. Noticed a strong smell of gas fumes when driving and after getting to campground. Thought it might be a Evap issue. But it turned out that mice have been getting onto our engine and one of them chewed a hole in what I believe is the return gas fitting coming of the fuel rail on the v10. The repair is a simple one if you can find the right part it took me four hours with more then 8 stops at part stores and another half dozen calls to other stores to finally find one. Hopefully you all won't have to need to do this repair but if you do I've included a picture of the right repair kit. You could also use 3/8" fitting with a 3/8" outlet if your existing house is long enough. Make sure it is for Ford gas lines.
They got my 2018 26x over the winter too, I believe it was squirrels and not mice. I had gas pouring down when I got it started it last month.
If it is the drivers side, it is the fuel supply at about 35-40psi. The driver's side connection to the fuel rail goes directly back to the fuel pump in the tank.
As it was the supply I decided to replace the line instead of patching. I have it on order from my local Ford dealership. Attached is the fuel diagram for my 2018, it is item 9J338. I believe it is the same part used back to 2010.
The supply/return pipes from the fuel rail have another connection point before they go back to the rear of the vehicle. They are on the drivers side between the chassis frame & transmission. The red connection with the white fuel sticker goes to the fuel rail on the drivers side.