Auxiliary fuel tanks are additional tanks besides the actual fuel tank. Do under-bed auxiliary fuel tanks for pick-up trucks exist?

When you’re traveling over long distances or are stuck in an emergency, an auxiliary fuel tank can be very helpful.

While in-bed auxiliary tanks are more common, under-bed tanks can also be found. These are usually held in the spare tire storage cavity.

There are differences in the types of auxiliary tanks available, and under-bed tanks can actually be quite beneficial.

We looked into the types of under-bed tanks and compared them with in-bed ones to collect all the information anyone would need on this topic.

Do Under Bed Auxiliary Fuel Tanks For Pickup Trucks Exist?



Benefits of Auxiliary Fuel Tanks

Having extra fuel can be very useful, especially if you travel over long distances quite often. An auxiliary tank helps because with the extra fuel, you can travel for more miles than you would with only one tank.

It’s also much more convenient to have extra fuel on hand, since if you’re traveling over a long distance – especially between towns and cities – you don’t have to stop at random gas stations and risk using the low-quality fuel. This fuel is also usually expensive, so you can save up on money and make sure your vehicle stays safe from the effects of bad fuel.

On top of that, not having to stop at random stations will also save you a lot of time.

Auxiliary tanks are also very useful if you’re carrying heavy loads. Heavier loads will usually result in higher fuel consumption, so if your auxiliary tank is full, you don’t have to worry about this.

Difference Between In-Bed and Under-Bed Auxiliary Tanks

The main difference between in-bed and under-bed auxiliary tanks is pretty clear. In-bed tanks are kept within the bed itself, and will usually take up space.

Having an under-bed auxiliary tank will give you more space within the bed of the pick-up truck to store items, which can be useful if you’re using it for transporting items, such as during a move.

Under-bed tanks will be stored in the spare tire cavity, which does have the problem of leaving no space for a spare tire. If you’re traveling over a longer distance, having an under-bed fuel tank means that while you have the fuel to travel far, you may not have a tire to back you up in case of an emergency.

Like spare tires kept in the cavity, a mounting stud is slid through the tank which can be held securely with a mountain plate. You can keep the fuel in the tank and transfer it to your main tank whenever the need arises. There is a controller with a gauge and a push button start and stop transfers. You can control these whenever needed.

One problem that arises with such tanks is that people may accidentally leave the switch on. This can result in your main fuel tank getting overfilled. Some tanks come with a return pipe so any excess fuel can be pushed back, but if your tank doesn’t have this feature, you’d have to be very careful about keeping an eye on the switch.

Some tanks also have the feature to allow the fuel to flow into the main tank through gravity. With these, the main tank will only start running out of fuel once the auxiliary tank is empty. These types of tanks are usually in-bed ones though.

How Do I Install an Auxiliary Fuel Tank?

Installing the auxiliary tank is an easy job. All you need is the right tools and supplies to get through it.

First, you’d have to make sure you have enough space to keep the tank. If you’re installing the tank in-bed then you’d have to clean the bed. If the tank is an under-bed one, you’d have to clean out the tire storage cavity.

Most tanks will come with a kit which includes all the bolts you need to install it. If you don’t have one, look into the kind of bolts you’d need.

Mounting tabs are usually either along the edge or on the bottom. You should mark the spot you’d be installing it into carefully so you can make sure it’s held tight. Add the fuel line by removing the rubber plugs on the tank or punching a hole through them.

Now you should link the auxiliary tank to the main one with a pipe, then secure the tank with bolts and nuts to keep it in place.

Make sure you’ve installed it correctly, and that fuel cannot leak from the tank. Otherwise having an auxiliary tank would be useless. You should also make sure that it’s held in place securely and that fast or sudden movements due to bumps or brakes won’t make the tank come loose.

Regulations Around Truck Bed Fuel Tanks

The US Department of Transportation has some laws around the kind of portable fuel tanks you can keep in your trucks.

Any portable tanks you use must have an 18 gauge made of steel or aluminum. It should have durable fastening so that it is held in place with the bed of the truck or storage cavity in case of any accidents. It should also be mounted permanently with the main fuel tank.

It should also be electrically connectable to the vehicle itself, and should have leakage protection so no fuel leaks out while driving. Leakages can cause fires and can be very dangerous.

Auxiliary Fuel Tank Toolbox Combos

The main purpose of auxiliary fuel tanks is to provide extra storage for fuel, but some kinds have some extra features to offer. Some types of auxiliary tanks also come with storage space which lets you store tools, equipment and any other such things you might need when you’re on the road. These types of tanks are called auxiliary fuel tank toolbox combos and can be very useful.

Under-bed auxiliary tanks for pickup trucks can be found, but they are actually less common than in-bed ones.


Charles Redding

Charles Redding

I've spent many years selling cars, working with auto detailers, mechanics, dealership service teams, quoting and researching car insurance, modding my own cars, and much more.

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