How Does DeeZee Aux Tank Fill Main Tank of Vehicle

Updated 11/17/2025 | Published 12/09/2024

Question:

Looking at your DeeZee auxiliary fuel tank. DZ91752X My question is how does it transfer fuel into your regular fuel tank. I saw a picture of a tee that was plumbed into the main fuel line and is it gravity fed, because to me it would over fill your main tank. Does it have a pump? No one has quite answered that question or anybody looking at these is a whole lot smarter than me.

asked by: Eddy

Expert Reply:

Hey Eddy, so the DeeMax aux fuel tank part # DZ91752X is a gravity feed design and does not use any pumps. So what does that mean as far as over filling? If the fill line has a check valve built into it then you are okay to leave it open as that would prevent it from over filling. If there isn't a check valve then you'd have to open it, let the tank fill till it's near full and then close it.

expert reply by: Jameson C

Aux Tank Diagram
(click to enlarge)

Jameson C.

11/17/2025

Hey Eddy, how did things go with the gravity feed setup on your DeeZee auxiliary fuel tank? Did the check valve help keep your main tank from overfilling? Your update could make it easier for others looking at the same design.