Fuel Tank Bung

What Is a Fuel Tank Bung?

A fuel tank bung is a threaded fitting that is welded or pressed into a fuel tank wall to create a leak-proof port. These small but essential components serve as the connection point for fuel lines, petcocks, return lines, sending units, rollover valves, and other fuel system hardware. Without a properly installed bung, there is no reliable way to route fuel in or out of a custom or modified tank — making them a foundational part of any serious fuel system build.

Bungs are most commonly found in performance and racing applications, custom street rods, off-road builds, and anywhere a fabricator is constructing or modifying a fuel tank from scratch. They are also used when adding a fuel return line to a tank that was not originally designed for a return-style fuel injection system — a very common upgrade on EFI conversions.

Materials and Thread Standards

Fuel tank bungs are available in several materials, each suited to different applications. Aluminum bungs are lightweight and corrosion-resistant, making them popular in racing and performance builds where weight savings matter. Steel and stainless steel bungs offer superior strength and are often preferred for heavy-duty or high-pressure applications. Thread standards vary widely — NPT (National Pipe Taper), AN (Army-Navy), and BSP (British Standard Pipe) are all common, so matching the bung to your fitting standard is critical before purchasing.

What to Consider When Shopping for a Fuel Tank Bung

• Thread size and type: Confirm whether you need NPT, AN, or a metric thread to match your fittings and petcock.
• Material compatibility: Aluminum works well for gasoline; check compatibility if running E85 or other alternative fuels.
• Weld-in vs. press-in: Most high-performance bungs are designed to be welded in place for a permanent, leak-proof seal. Press-in or bung-nut styles suit situations where welding isn't practical.
• Flange diameter: Make sure the flange OD fits the available space on your tank without conflicting with nearby welds or seams.
• Fuel system type: Return-style EFI systems typically require two bungs — one for feed and one for return — while carbureted systems may only need one outlet port.

Top Brands in Fuel Tank Bungs

Red Horse Performance is the dominant name in this category, offering an extensive lineup of weld-in aluminum fuel tank bungs in a wide range of AN and NPT thread sizes. Known throughout the racing community for precision-machined aluminum fittings and fuel system components, Red Horse bungs are a go-to choice for builders who demand consistent thread quality and material integrity in high-performance and race-spec fuel systems.

Helix rounds out the category with a practical selection of fuel system fittings tailored toward performance street and racing applications. Helix has long been recognized for quality fuel delivery components, and their bung offering gives builders a reliable option when sourcing all their fuel system hardware from a single trusted supplier.

Where Fuel Tank Bungs Fit in Your Build

Fuel tank bungs fall under the broader Fuel Tank Bung category within Air and Fuel Delivery > Fuel Storage. Whether you are building a dedicated race car, converting a classic to EFI, or fabricating a custom off-road rig, selecting the right bung is one of the first steps toward a safe, functional, and professional-quality fuel system.