How Does the Land Cruiser Sub Gas System Work?

February 4, 2025

Many Toyota Land Cruiser models, especially 70 Series and 80 Series variants, are equipped with a sub-gas tank system. This setup adds extra fuel capacity, making it ideal for long-distance travel, remote expeditions, and areas where refueling stations are scarce.

Purpose of the Sub-Gas Tank

The sub-gas tank serves as an auxiliary fuel reservoir. Its primary role is to extend the vehicle’s range without the need for frequent stops. This is particularly useful for off-road adventures, overlanding, or in rural areas where fuel stations may be far apart.

Key Components

A typical Land Cruiser sub-gas tank system includes…

Sub Tank – A secondary fuel tank mounted under the vehicle, often behind the rear axle or under the cargo area.
Fuel Transfer Pump – An electric or manual pump that moves fuel from the sub-tank to the main tank.
Control Switch – Located on the dashboard, it allows the driver to start and stop the fuel transfer.
Fuel Lines – Hoses or pipes that carry fuel between the sub-tank and the main tank.
Gauges and Indicators – Some models have a dedicated sub-tank fuel gauge or a warning light when the sub-tank is low.

How It Works

The sub tank is filled separately through its filler cap or via a shared filler with a selector valve.
When the main tank fuel level gets low, the driver activates the transfer pump using the dashboard switch.
The pump transfers fuel from the sub tank into the main tank.
Once the main tank is sufficiently filled or the sub tank is empty, the driver switches off the pump.
The engine always draws fuel from the main tank, so the sub tank never feeds the engine directly.

Advantages

Extended Driving Range – Longer trips without frequent refueling.
Convenience – Easier to manage fuel supply in remote areas.
Flexibility – Ability to carry different fuel types in specific cases.

Maintenance Tips

Regularly check for leaks in the sub tank and fuel lines.
Test the transfer pump periodically to ensure it works.
Keep the fuel clean and avoid letting the sub tank sit unused for long periods.
Follow manufacturer guidelines for filter replacement and inspection intervals.

The Toyota Land Cruiser sub-gas tank system is a practical solution for long-distance travel and off-road use. By understanding how it works and maintaining it properly, owners can take full advantage of its extended range and reliability.