3 Fuel Tanks That Fits Under Tonneau Covers Conveniently

Auxiliary fuel tanks become necessary as a means of supplying your truck with fuel after you have burnt off all the fuel in your main or stock fuel tank,  in order to ensure that your journey does not stop due to fuel shortage.

These truck bed-based tanks have an inbuilt and automatic mechanism that enables them to take over fuel supply to the engine, the moment you run out of fuel in the main fuel tank without any delay.

These auxiliary tanks are fully baffled in such a way that sloshing is greatly minimized and are mostly supplied complete with all the required installation components and instructions.

They can be used with retractable tonneau covers and camper shells too. The question, therefore, is: Are There Fuel Tanks That Fits Under Tonneau Cover?

There are different sizes of fuel tanks that can fit under your truck bed covers, notable among which is the 37 Gallon Roll Top Fuel Tank. This tank fits both short and long truck beds such as under Pace-Edwards and retractable truck covers.

It is available in 14 gauge aluminized steel and a black powder coat finish mainly. We also have the 50/60 Gallon Low Profile Fuel Tank.

Its height allows it to fit underneath any truck’s tonneau cover, whether it is a short or a long bed pick up truck, and is also available in 14 gauge aluminized steel with a black powder coat finish or a bright and polished aluminium diamond plate.

There is also the 75 Gallon Space Saving Fuel Tank, which is only 18” deep and guarantees increase in fuel capacity while allowing for enough cargo space.

This tank also fits both long and short truck beds, which is available in 14 gauge aluminized steel with black powder coat finish only.

Finally, there is the 91/98 Gallon High Capacity Fuel Tank, which is the largest auxiliary tank that fits only the long-bed kinds of trucks. You have the option of choosing from 14 gauge aluminized steel with black powder coat finish or the bright polished aluminum diamond plate.

Why You Should Own An Auxiliary Fuel Tank

An auxiliary tank ensures that you do not run out on fuel while on any journey by taking over fuel supply to the engine automatically,  the moment your stock tank or main tank is empty. This has the advantage of increasing your driving range. An auxiliary tank takes over this function due to the presence of an inbuilt pump in it.

Are There Things I Need To Keep In Mind Before Purchasing An Under Cover Bed Tank For My Truck?

Yes, there are. To start with, though most undercover fuel tanks fit both long and short truck beds, there are still tanks that fit only trucks with long beds. As a result of this, you should know the exact specifications or dimensions of your truck bed before any bed fuel tank purchase in order to avoid buying the wrong one.

Which Materials Are The Fuel Tanks Made Of?

Auxiliary truck bed fuel tanks are mainly produced with aluminized steel or aluminum diamond plate, both of which are materials that confer on these tanks excessive durability which guards against leaking of any kind.

Do All Tonneau Covers Take A Tank Under Them?

Most tonneau covers can take auxiliary fuel tanks under them. So, basically, all tonneau covers can take a fuel tank under them. Notable among the bed covers that take auxiliary fuel tanks are the retractable truck bed covers, tonneau covers, and camper shells.

Do I Need Any Tools To Keep A Tank Under A Cover?

The only tools you may require to keep an auxiliary fuel tank under a truck bed cover are a pair of pliers, scissors or razor blades, hand gloves, and masking tape.

With these, you will be able to cut the conducting wires to and from the tank as well as wrap areas where the wires are joined together with the masking tape,  while the hand gloves are protected against possible injuries while working.

How Do I Install An Auxiliary Tank?

To install an auxiliary fuel tank does not involve more than placing the tank at any position of your choosing such that it will not interfere with your cargo unnecessarily.

Thereafter, you should proceed to connect the relevant conducting wires from the fuse box in the truck to the tank and also from the tank to the fuse box. These connections are necessary in order to enable the truck’s battery to operate the automatic fuel pump in the auxiliary tank.


What Is An Auxiliary Fuel Tank?

An auxiliary fuel tank is an additional tank which is usually placed in the truck bed that will take over fuel supply from the main or stock tank when it is empty.

The use of an auxiliary tank will extend your driving range by enabling you to continue with your journey even after your stock tank has run dry. They come in different sizes and the capacity of your truck bed determines which size of auxiliary tank you should use.

Are Auxiliary Fuel Tanks Legal In California?

Though the use of auxiliary fuel tanks is legal in most parts of the United States, the same can not be said in California, because the use of auxiliary tanks is subject to California’s anti-tampering laws.

This implies that the installation of auxiliary tanks on emission-controlled vehicles is prohibited unless such tanks have been both evaluated and certified by the Air Resources Board.

And there are auxiliary tanks that have met this condition in California such as the F-71-150, F-71-51, F-75-52 and F-71-53. These are the tanks that have met the Executive Order for auxiliary tanks OBD II system requirements.

How Does An Auxiliary Fuel Tank Work?

An auxiliary fuel tank works by taking over fuel supply to the combustion chamber of the engine automatically from the main or stock tank the moment it is empty, so as to enable you to continue your journey unhindered. This it does via the electrically controlled fuel pump in it which is powered by its battery.

What Are The Best Auxiliary Tanks In The Market?

The best auxiliary tanks in the market are those aluminium and toolbox type, which are corrosion resistant with fully welded seams and re-inforced lids.

These tanks also have a universal fit which means that they are suitable for use in most vehicles. Some examples of these tanks are RDS MFG INC 72773 Girl Tank and the RDS MFG INC 72775 Fuel Tank, which are sold on Amazon.

Can You Put Gasoline In A Fuel Transfer Tank?

Yes, you can because many of these fuel tanks have systems that are suitable for either of gas and diesel. Your choice of these tanks should therefore be based on the kind of system you wish to install in your truck. So, essentially, you can use gasoline in an auxiliary fuel tank provided the system you have is compatible with it.

Does A Fuel Tank Need To Be Grounded?

Yes, auxiliary tanks for diesel and gas need to be grounded whenever you are fuelling either your equipment or vehicle because an explosion can occur unexpectedly.

Lightning may strike or when there is any accidental contact with a high voltage line which can lead to an accumulation of static and electrical energy within the tank, that may trigger an accident.

To avoid this from happening, grounding is highly advised. Similarly, grounding is necessary when fuel tanks are placed in hazardous or even non-hazardous areas.

Grounding removes the static charges in order to guard against incidents of fire at the sites where tanks are kept, a process which is aided by the increased humidity of the conducting plates.

For effective grounding, ground anodes are simply the best for industrial storage tanks, which are usually connected to the tank shell and placed in close proximity to the tank.

What Are The Differences Between Grounding, Bonding And Earthing?


The terms grounding, bonding and earthing are all related to safety requirements and may easily be regarded as being the same, but heck, they have a world of differences among them.

Grounding simply refers to the fusion of all parts of conductors that convey electricity to the earth for safe dissipation, this essentially means the safety of persons or equipment. Due to safety concerns, grounding in fuel storage tanks should be made a priority.

All industries must recognize the necessity for grounding so that severe accidents can be effectively avoided on the sites. Grounding may not always be necessary for above-ground ground storage tanks because they are equipped with self-protecting properties that reduce any added grounding requirements.

Where the lowest part of a tank is made of a metal which is connected to the earth directly,  the tank is not liable to accumulating static electricity due to excellent connectivity.


While bonding basically refers to the process of connecting two or more electrical conductors by attaching the metal parts which do not carry any electricity and these can be either pipes or wires or even two wires.


Earthing, put simply, is the process of connecting dead or neutral parts to the earth surface for the safe discharge of either static or current electricity.

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How Do You Save Gas In A Truck?

The primary concern of every motorist is how effectively they can save gas with extended driving ranges. To achieve this objective, there are various ways of going about the entire process. First, if you are using a tonneau cover, traveling with it closed is your best bet in fuel economy measures.

This is because when it is closed, you are essentially reducing air drag on your vehicle which increases your vehicle’s aerodynamics.

Reduction in air drag means a reduction in the resistance against which your vehicle will have to work and that translates into increased fuel economy.

Though it is argued that this saves a negligible quantity of fuel, but take into consideration the long-distance or hours you may have to travel and you may come up with quite a significant figure.

Always make sure that your tyres are properly inflated because deflated tyres increase the friction between your tyres and the road which will translate into more fuel consumption too.

Weather conditions also affect your gas mileage efficiency because when the weather is hot, you are bound to use the AC unit of the vehicle which will consume more gas.

Similarly, in hot weather, if we don’t use the AC, we may alternatively be forced to open the windows, and opening the windows to let in a breath of fresh and cooler air means reduced vehicular aerodynamics, which leads to decreased gas mileage as well.

Finally, your gas mileage is in direct proportion to the weight of the cargo you carry. The heavier this cargo is, the more the gas your vehicle consumes. Simple and fair enough, right? Well, that’s just really it.

Final Thoughts

Auxiliary or under cover tanks save a lot of frustration and time for the simple fact that they extend your driving range, even when you end up with an empty tank.

To make it more interesting, they come in multiple sizes and specifications which means that you will eventually get that which will be compatible with your vehicle.

However, there are places where a sort of restriction is placed on their use such as California in the United States,  and you will do well to adhere to any restrictions so placed, for your safety and that of others too.

Though there is some relief in knowing that some or most of these tanks are equipped with features that address the issue of accidents while using them, but it is still recommended that you take other safety measures where necessary too. You can never be too careful or so I think. Thank you for your time.

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