Auxiliary fuel tanks offer the ability to dramatically extend the amount of diesel fuel you can hold in your factory truck tank. The key benefit is the built-in fuel system that pumps diesel fuel into your main factory truck tank while you are on the road.
There are multiple auxiliary fuel tank systems available with a variety of options, features and benefits. This article will explain how the auxiliary fuel systems work and highlight a few of the best options available for your truck.
Can An Auxiliary Fuel Tank System work with Gasoline?
Unfortunately, the answer is no. Auxiliary fuel tank systems require trucks with diesel fuel.
How Difficult is it to Install an Auxiliary Fuel System?
The installation process typically takes between 2 to 4 hours to install. Anyone with basic mechanical skills can install an auxiliary fuel tank system. The kits include all the parts necessary to install.
If you are not comfortable doing the installation yourself, we recommend going to a local auto repair shop for assistance with the installation. Just explain which auxiliary fuel system you are using and provide your mechanic with the instructions for the installation.
Trax 4 Auxiliary Fuel Tank System
Transfer Flow offers one of the most advanced auxiliary fuel tank systems on the market. The Trax 4 system features an app designed to work with Apple and Android phones that lets you view in real time the fuel capacity in your auxiliary fuel tank as well as in your pickup’s tank.
The Trax 4 system is a fully computer controlled fuel management system that seamlessly transfers fuel from a Transfer Flow auxiliary tank to your truck’s main fuel tank. You can setup the Trax 4 system to transfer fuel at pre-determined levels into your vehicle fuel tank at set levels that you determine. The fuel transfer happens while your vehicle is in operation on the road.
If you prefer not to use a mobile phone app, you have the option of using an in cab fuel level monitor with an LCD screen. This lets you monitor your current fuel levels from directly inside your truck cab.
Trax 4 Truck Compatibility
The Trax 4 system is designed for use with the following diesel trucks:
- 2008 and newer Ford trucks
- 2010 and newer GM trucks
- 2010 and newer Ram trucks
Trax 4 Auxiliary Fuel System Sizes and Options
Transfer Flow offers Auxiliary Fuel Tanks with the Trax 4 system on two main types of fuel tanks:
- The standalone auxiliary fuel tank
- As a fuel tank toolbox combination unit
Before purchasing a unit, it is very important to take accurate measurements of the length, width, and height in your truck bed. These fuel tanks will sit directly behind the passenger cab. So the length of your auxiliary tank will actually be the width of your truck bed.
In Bed Auxiliary Fuel Tank
Transfer Flow’s premium steel rectangular auxiliary fuel tanks are available in four sizes: 40 gallon, 50 gallon, 75 gallon and 100 gallon. These tanks are highly durable steel tanks with a sleek glossy black powder coat that provides long term protection for the tanks in outdoor conditions.
The 40 gallon size includes a unique front diagonal fill neck which reduces the height of the filler cap. The larger 50, 75, and 100 gallon sizes have a filler neck cap on the top panel of the fuel tank which adds an extra 3 inches of height.
All tank sizes have mounting brackets located on the width side of the tank that add an extra 1.5 inches to the width of each tank.
Transfer Flow Aux Tank Sizes
- See Tank: 40 gallon – 48 inches long by 19 inches wide by 19.38 inches high
- See Tank: 50 gallon* – 60.75 inches long by 18.5 inches wide by 18.35 inches high
- See Tank: 75 gallon* – 60.75 inches long by 20.5 inches wide by 22.75 inches high
- See Tank: 100 gallon* – 60.75 inches long by 26.75 inches wide by 22.75 inches high
*50 / 75 / 100 gallon sizes are notched and have a bottom length of 55.25 inches.
Auxiliary Tank Toolbox Combos
If you prefer to have a toolbox included with your fuel tank, Transfer Flow provides a really nice combo option. These combo tanks include the same high grade steel design with glossy black powder coat.
The top half of the tank includes a toolbox that runs the full length of the tank. The bottom portion of the tank houses the Trax 4 powered auxiliary fuel tank. Transfer Flow offers two sizes for its auxiliary fuel tank toolbox combo: 40 gallon and 70 gallon.
Both tanks house the filler neck inside the toolbox of the tank which reduces the overall height of the tank. The 40 gallon size is designed to sit in front of the wheel well.
The larger 70 gallon size is designed so the top toolbox sits on the truck bed rails. The tank is designed with a T shape that allows the lower portion of the fuel tank to fit inside your pickup bed walls.
Keep in mind, the front mounting tabs on both tanks add an extra 1.5 inches to the width of the tank.Transfer Flow Aux Tank Toolbox Combo Sizes
- See Tank: 40 gallon – 59 inches long by 21 inches wide by 21 inches high
- See Tank: 70 gallon – 73 inches long by 24.5 inches wide by 27.75 inches high
For more information, visit our selection of Transfer Flow Auxiliary Fuel Tanks.
Auto Fuel Controller
The Fuelbox Auto Fuel Controller is an advanced auxiliary fuel tank system designed for diesel powered trucks. The Auto Fuel Controller works on the following diesel trucks:
- Dodge Ram
The Auto Fuel Controller works by automatically filling your main fuel tank as you drive. When your fuel tank falls to ¼ of tank, the auto fuel controller activates a transfer pump that transfers fuel from your auxiliary tank directly into your factory fuel tank.
The auto fuel controller will automatically shut-off when your stock fuel tank is near full or your auxiliary fuel tank is empty. You have the choice of setting up the automatic fuel controller for auto operation or you can set it for manual usage by operating a switch placed in the truck cab.
The auto fuel controller includes an LED screen that directly monitors the fuel levels in your auxiliary fuel tank. You can attach this LED screen to your dashboard with Velcro as it does not require that you drill into the dashboard.
Choose the Digital Display to use with the Auto Fuel Controller
When selecting the Fuelbox Auto Fuel Controller, you choose which type of digital display to use:
- Plug & Play Controller
- Digital Display Controller
Plug & Play Controller
We recommend choosing to the Plug & Play controller because this option shows the fuel levels in your factory fuel tank as well as the fuel levels in your auxiliary fuel tank. Additionally, the plug & play controller plugs directly into your on-board diagnostic (OBD-II) port on your truck. This makes for a very easy installation and also avoids the factory wire harness.
Digital Display Controller
This option requires you manually program the display for the year and make of your vehicle. Additionally, this option will only show the fuel level inside your Fuelbox auxiliary fuel tank. It will not show the fuel level inside your factory fuel tank.
The digital display controller operates by monitoring the fuel level of the stock tank and monitor the voltage of the sending unit which knows when to turn the auto fuel controller on or off.
Fuel Controller Auxiliary Tank Options
Fuelbox offers multiple shapes and sizes that will fit into any type of pickup truck size. The Fuelbox is most well-known for its fuel tank toolbox combo models. However Fuelbox also offers auxiliary fuel tanks in addition to the tank toolbox options.
We will highlight a few options below to give you a general idea of the available options. However, our Fuelbox Fuel Tanks for a full list of every Fuelbox tank size available and their exact measurements.
Aluminum Auxiliary Fuel Tank
These auxiliary fuel tanks all work with Fuelbox’s Auto Fuel Controller System. The aux tanks also include a tapered design which notches the lower portion of the tank which reduces the bottom length of each tank. The smaller sizes have a notched bottom length of 48 inches while the largest size has a notched bottom length of the 53 inches.
All Fuelbox tanks come as smooth silver aluminum. You have the ability to fully customize the tank to your preference:
- Add the Auto Fuel Controller System or a 13GPM manual transfer pump
- Add a diamond plate design
- Add a charcoal black spray liner to increase the tank durability
- Add a lockable gas cap
Aux Fuel Tank Sizes
- Check Tank: 40 gallon – 62 inches long by 10 inches wide by 19.5 inches high
- Check Tank: 50 gallon – 60 inches long by 16 inches wide by 15 inches high
- Check Tank: 68 gallon – 60 inches long by 19 inches wide by 19.5 inches high
- Check Tank: 85 gallon – 60 inches long by 25 inches wide by 19.5 inches high
L-Shaped Auxiliary Fuel Tank
L-shaped fuel tanks are frequently paired with existing truck toolboxes. The lower portion of the L shape is used for going underneath the truck toolbox. The idea is to create a complete rectangle when you push the L-shaped tank underneath your toolbox.
The key measurement for the L-shaped tank is the height of the lower L. You want to first measure the height of your toolbox to find out how much space you have to fit the L shape height.
L-Shaped Aux Tank Sizes:
- Check Tank: 55 gallon – 53 inches long by 23.625 inches wide by 19 inches high (8 inches Low L height)
- Check Tank: 70 gallon – 53 inches long by 28 inches wide by 19 inches high (8 inches Low L height)
Full L shape measurements (55 gallon size):
- Top Height (A) – 19 inches
- Bottom Width (B) – 23.625 inches
- Bottom Length (C) – 53 inches
- Low L Height (D) – 8 inches
- Mid Width (E) – 14.625 inches
- Mid Height (F) – 7.38 inches
- Top L Width (G) 9 inches
Full L shape measurements (70 gallon size):
- Top Height (A) – 19 inches
- Bottom Width (B) – 28 inches
- Bottom Length (C) – 53 inches
- Low L Height (D) – 8 inches
- Mid Width (E) – 17 inches
- Mid Height (F) – 8.5 inches
- Top L Width (G) 11 inches
Compare all Fuelbox Auxiliary Tanks.
Freedom Fill Auxiliary Fuel Tank System
ATTA’s Freedom Fill Auxiliary Fuel Tank system is an automatic system that will fill your factory diesel fuel tank when your factory tank is at half a tank. The Freedom Fill system will activate and transfer fuel from your auxiliary fuel tank into your factory fuel tank until your factory tank is exactly three quarters full.
There is a dash board switch light which turns on letting you know when the ATTA Freedom Fill system is actively transferring fuel. Key things to know about the ATTA Freedom Fill system:
- The ATTA freedom fill only activates when your factory fuel tank is at half a tank of fuel.
- The ATTA freedom fill turns off when your factory fuel tank gets filled to ¾ of a tank.
- If your factory fuel tank falls below ½ a tank of fuel, that means your auxiliary tank is empty and needs to be filled up.
- You can always override the auto fuel system by turning off the ATTA freedom fill switch that is mounted to your factory dash board.
When purchasing the Freedom Fill System, you need to specify the year, make and model of your truck, so the Freedom Fill system can be properly programmed for your vehicle.
Push N Fuel System
ATTA also offers a more manual auxiliary fuel tank system. The Push N Fuel system operates from a panel mounted to your dash board. Fuel gets transferred when you activate the switch and manually begin transferring fuel.
The main thing to keep in mind is that this system is entirely manual. This means you need to turn the switch off when your gas tank reaches ¾ of a fuel tank or you can risk over-filling your factory fuel tank.
We recommend the ATTA Freedom Fill system instead of the Push N Fuel because of the built-in safety features that shut off the fuel transfer once your tank is ¾ full.
Freedom Fill Aux Fuel Tanks
The following auxiliary fuel tanks work with both ATTA fuel tank systems. We highlight a few of the popular options below.
To see all available ATTA fuel tank sizes, see our ATTA auxiliary fuel tanks.
Rectangular Diesel Auxiliary Fuel Tank
ATTA offers a diamond plate rectangular aux tank in a wide variety of sizes designed to fit multiple vehicle sizes. All tanks require you to choose either the ATTA Freedom Fill System or the ATTA Push N Fuel System.
These tanks are highly customizable. You can pair the tank with a sleek black powder coat or a spray on liner that helps protect your tank from the outdoor elements.
Rectangular Tank Sizes:
- Check Tank: 40 gallon – 54 inches long by 10 inches wide by 18 inches high
- Check Tank: 50 gallon – 60 inches long by 12 inches wide by 18 inches high
- Check Tank: 80 gallon – 60 inches long by 18 inches wide by 18 inches high
- Check Tank: 99 gallon – 60 inches long by 22 inches wide by 18 inches high
- Check Tank: 110 gallon – 60 inches long by 25 inches wide by 18 inches high
Roll Top Auxiliary Fuel Tank
If you have a tonneau cover on your truck, we recommend the following tank which is designed with just 14 inches of height and will sit well below your bed cover.
Roll Top Bedcover Sizes:
- Check Tank: 45 gallon – 60 inches long by 18 inches wide by 14 inches high
- Check Tank: 72 gallon – 60 inches long by 25 inches wide by 14 inches high
You can also browse our full selection of Auxiliary Fuel Tanks for sale.