Cascadia Fuel Return Shutoff

That is what they are and where.

 

It does both return and shut off drawing from the tanks. The actual valve system used to be called Equi-flow, and you could draw off one tank by closing off the other, and the return was closed at the same time so the shut off tank didn't get overfilled with returned fuel.

Not all FL trucks had the system that could shut off one tank so easily, and it eliminated the crossover line on the bottom of the truck between the tanks.

I believe they used the system without shut offs in some applications, as we had 5 FLD 120s with no shutoffs from the 2001 model year. A 2000 Columbia had a rotary switch, but that had an ISX and electric pre charge pump to prime the engine fuel system.

 

It shuts the tank off, literally. I have only touched it on a few trucks, and only to get one running again if 1 tank went empty for some reason while there was fuel in the other tank. Beats walking or waiting for help to show up.

Another advantage is that the tanks will even out if you can only get fuel into either one but not the other, easily, like if one side of a pull through set is out of service and the place is busy.

Repositioning to fill the other side isn't always easy.

 

What are you wanting to do? I don't think there is a way to get a properly functioning system to shut off the return and run it into the other side while drawing from both without removing a line.