Why do older Fords have 2 gas tanks?
Two gas tanks were used to extend a Ford's driving range, especially for long trips or heavy towing. The second tank provided extra fuel capacity and could be selected as the engine's fuel source.
Historical context and purpose
In a era when fueling infrastructure was less extensive and road trips could involve long stretches with few stations, automakers offered auxiliary tanks to reduce refueling frequency and improve operational flexibility. Ford made dual-tank configurations available on several trucks and cargo vans, with the second tank often mounted behind the cab or in a rear wheel well. A dash-mounted selector switch let the driver choose which tank fed the engine. This setup was particularly common on the Ford F-Series line and various commercial vehicles from roughly the 1960s through the 1990s. While not universal, the dual-tank option was a practical way to boost range before modern big-tank designs and more efficient engines became standard.
How the dual-tank system worked
Most two-tank installations used two separate pickups and, in many cases, two fuel pumps feeding a common line to the engine. A dash-mounted selector valve or switch determined which tank supplied fuel to the engine. Some systems routed fuel from the chosen tank to the engine directly, while others allowed both pumps to feed the engine but used the selector to indicate which tank was in service. The auxiliary tank was typically smaller and located in a separate space—often behind the cab or in the left rear fender area—and it required its own filler neck and venting hardware. The result was an extended range and a reserve option that could be tapped when the main tank approached empty.
Common configurations and practical impact
The dual-tank arrangement varied by model and year, but several common features emerged across Ford trucks and vans that offered the setup.
- Extended driving range for long road trips, remote routes, and rural service.
- Improved capability for towing heavy loads without frequent refueling stops.
- Two fuel tanks with separate filler caps and venting hardware, connected to a shared engine feed via a selector valve.
- Dash switch or control valve to choose the active tank and monitor fuel supply.
- Typically, electric pumps were installed in each tank to feed the engine when that tank was selected.
In practice, the two-tank setup was a pragmatic solution for its time, enabling longer operations between fills and adding a usable reserve. It also introduced more maintenance considerations, such as ensuring both tanks and lines remained free of rust and leaks and that the selector mechanism functioned correctly.
Examples of models and configurations
Dual-tank configurations appeared on various Ford trucks and some cargo vans. The most common arrangement placed the auxiliary tank behind the cab or within the left rear fender area, sometimes with two filler necks visible on opposite sides of the vehicle. Some later dual-tank setups used a single gauge and a dash selector, while others offered separate indicators for each tank. If you’re evaluating or restoring an older Ford with two tanks, verify the condition of both tanks, the selector valve, the fuel lines, and the integrity of the filler caps and venting hardware.
Maintenance and buying tips
When assessing a used Ford with two tanks, consider these checks to avoid surprises:
- Inspect both tanks for rust, leaks, and signs of corrosion around the fittings, fillers, and vent lines.
- Test both fuel pumps and the selector valve to confirm reliable switching between tanks.
- Verify the accuracy of the fuel gauge and ensure switching between tanks is smooth and responsive.
- Check hoses, vent lines, and connections for cracks or brittleness, and ensure proper venting to prevent vapor buildup.
- Review service history or prior restoration work to gauge parts availability and potential replacement needs for older dual-tank components.
With careful inspection and proper maintenance, a two-tank Ford can remain a functional and interesting feature of a classic truck or van rather than a reliability risk.
Summary
Older Fords with two gas tanks used an auxiliary tank to extend driving range and improve versatility for long-distance travel and heavy towing. The system typically included a secondary tank with its own feed, a dash selector to switch between tanks, and two filler caps. While helpful in its era, the dual-tank setup adds maintenance complexity and is less common in modern Ford lineups. For collectors and restorers, understanding the layout helps assess condition, value, and authenticity in classic Ford trucks and vans.
What is the purpose of the auxiliary fuel tank?
AUXILIARY FUEL TANKS are defined by the Vehicle Equipement Safety Commission as an additional fuel tank and any other componets attached directly thereto designed to supplement the vehicle's fuel carrying capability beyond that provided by the vehicle manfacturer.
What is the point of two gas tanks?
First off, it's easier to design and install two smaller tanks compared to a single humongous one. Having two tanks also means the weight of the extra fuel — 6.1 pounds per U.S. gallon — can be distributed more evenly around the chassis.
What car has two gas tanks?
You have a button on the dash fuel and that switches a separate fuel pump. For the left and right tanks. And also swaps. The uh indication on the fuel gauge around so a bit like an airplane.
Why do old Fords have two gas tanks?
Most dual-tank Fords had one tank up front and another in the back. The layout could help with weight distribution and space management. A gallon of gas weighs around six pounds. A 1997 F-150 with a single mid-mounted fuel tank holds around 25 gallons, which equates to around 150 pounds of liquid sloshing around.
