Auxiliary Gas Tanks for Pickup Trucks: A Complete Guide
If you’ve ever found yourself calculating fuel stops on a long haul or wishing you had just a bit more range to reach that remote job site, you’re not alone. For pickup truck owners who rely on their vehicles for work, adventure, or heavy towing, running out of fuel isn’t just an inconvenience—it’s a major disruption. This is where auxiliary fuel tanks for pickup trucks come into play. An auxiliary fuel tank is an add-on system that significantly increases your vehicle’s driving range by holding additional gasoline or diesel. This complete guide will walk you through everything you need to know, from the different types available to the crucial installation details, helping you decide if this upgrade is right for your rig.
Why Consider an Auxiliary Fuel Tank?
The primary reason for installing an auxiliary diesel tank or a gasoline counterpart is simple: extended range. But the benefits go beyond just skipping a few gas stations.
- Uninterrupted Travel: Perfect for long-distance road trips, towing trailers, or exploring off-grid locations where fuel stations are scarce.
- Enhanced Productivity: For tradespeople and fleets, less time spent refueling means more time on the job, directly impacting your bottom line.
- Improved Convenience: Carry your own fuel supply for generators, equipment, or to help another vehicle in a pinch.
- Better Fuel Management: Many systems allow you to monitor and transfer fuel with precision, helping you track consumption and costs.
According to a report from the U.S. Department of Energy’s Alternative Fuels Data Center, the average fuel economy for a light-duty pickup truck can be significantly reduced under load, making range extension a practical consideration for many owners.
Types of Auxiliary Fuel Tanks
Not all auxiliary fuel tanks are created equal. The right choice depends on your truck’s model, your intended use, and how much space you’re willing to sacrifice.
In-Bed Auxiliary Tanks
These are the most common type. They sit in your truck bed, typically against the front or side, and are a straightforward installation. They come in various shapes and capacities, from compact 30-gallon units to larger 60-gallon models. The main trade-off is the loss of some bed space, but they are often the most cost-effective option.
Replacement Toolbox Tanks
This is a brilliant two-in-one solution. These units look and function like a standard truck bed toolbox but have a integrated fuel tank. You get secure storage for your tools while simultaneously adding significant fuel capacity without taking up additional bed space. This is a popular choice for contractors.
Under-Body or Transfer Flow Tanks
For those who need to preserve every inch of their truck bed, under-body tanks are the answer. Mounted to the frame rail underneath the truck, these tanks are out of sight and out of the way. They are more complex to install but offer a clean, OEM-like look. They are particularly common for diesel-powered trucks.
Key Features to Look For
When shopping for an auxiliary fuel tank, don’t just look at the price tag. The quality of materials and included components are critical for safety and performance.
- Material: Look for tanks made from cross-linked polyethylene or aluminum. Poly tanks are impact-resistant and won’t rust, while aluminum is lightweight and durable.
- Fuel Transfer System: How does the fuel get from the auxiliary tank to your main tank? Systems can be gravity-fed, use a 12-volt electric pump, or a more advanced, automatic system that monitors your main tank level.
- Venting and Spill Prevention: A proper venting system is non-negotiable for safety. Ensure the tank has an integrated rollover valve and meets all relevant standards.
- Gauges and Monitoring: You’ll want to know how much fuel is in your auxiliary tank. Options range from simple sight glasses to sophisticated electronic gauges.
Installation: DIY or Professional?
Installing a pickup truck auxiliary fuel tank can range from a moderately challenging DIY project to a job strictly for professionals.
A simple in-bed, gravity-fed tank might be within the capabilities of a confident home mechanic. However, any installation involving drilling into the main fuel tank for a transfer pump, complex wiring, or under-body fabrication should be handled by a certified professional. Mike Reynolds, a master technician with over 15 years of experience in commercial vehicle outfitting, advises, “The biggest mistake we see is improper venting and insecure mounting. A fuel tank is not something you want coming loose on the highway. If you have any doubt about the plumbing or electrical work, the investment in professional installation is worth the peace of mind.”
Always check your local and state regulations regarding auxiliary fuel tanks, as some jurisdictions have specific requirements for capacity and installation.
Comparing Popular Auxiliary Fuel Tank Brands
To help you make an informed decision, here’s a quick comparison of some well-regarded brands in the market.
| Brand | Best For | Common Materials | Notable Features |
|---|---|---|---|
| Transfer Flow | OEM-style, Under-Body | Aluminum, Steel | CARB-compliant, extensive vehicle-specific designs |
| RDS | Toolbox Combo & In-Bed | Polyethylene, Aluminum | Dual-functionality, wide range of capacities |
| Titan | High-Capacity Replacement | Polyethylene | Large, durable tanks often with integrated fueling systems |
| Auxiliary Fuel Systems | Heavy-Duty & Fleet Use | Aluminum | Robust construction, focus on diesel applications |
Maintenance and Safety Best Practices
An auxiliary fuel tank is a responsibility. Proper maintenance ensures it remains a reliable asset.
- Regular Inspections: Periodically check for leaks, cracks, and loose fittings, especially after off-road excursions.
- Keep It Full: When not in use for long periods, keeping the tank full minimizes internal condensation, which can lead to water contamination in your fuel.
- Use Quality Fuel: Don’t put “old” or questionable fuel into your auxiliary tank. It will eventually end up in your engine.
- Follow the Manual: Adhere to the manufacturer’s specific maintenance schedule for pumps and filters.
A study highlighted by the National Fire Protection Association (NFPA) underscores that proper installation and maintenance of fuel-bearing systems are critical in preventing vehicle fires.
Frequently Asked Questions
Q: Are auxiliary fuel tanks legal in all states?
A: While generally legal, regulations vary by state, particularly concerning capacity and how the fuel is dispensed. It is your responsibility to check with your local Department of Motor Vehicles or environmental protection agency to ensure compliance.
Q: Can I install an auxiliary fuel tank on a truck that is still under factory warranty?
A: Yes, but you must ensure the installation does not void your warranty. Using a CARB-compliant tank and having it installed by a certified professional is the best way to avoid any issues with your dealership.
Q: How long does it take to transfer fuel from the auxiliary tank?
A: Transfer times vary widely. A gravity-fed system might take 30-60 minutes for a full transfer, while a system with a high-flow 12V pump can accomplish the same task in 10-15 minutes. Check the pump’s gallons-per-minute (GPM) rating.
Q: Do I need to inform my insurance company?
A: It is highly recommended. A significant modification like an auxiliary fuel tank can affect your policy. Most companies will simply note the modification, but failure to disclose it could potentially cause problems with a future claim.
Final Thoughts
Investing in an auxiliary fuel tank for your pickup truck is a strategic upgrade that pays dividends in range, convenience, and productivity. Whether you opt for a simple in-bed model or a sophisticated under-body system, the key is to prioritize quality, proper installation, and ongoing maintenance. By carefully considering your needs and doing your research, you can confidently equip your truck to go the extra mile—literally.
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