Gates 31691 Fuel Tank Cap

Gates 31691 Regular Locking Fuel Cap

The Gates 31691 Regular Locking Fuel Cap is built for older Ford, Chevrolet, Mercury, Pontiac, Buick, Oldsmobile, Jeep, Chrysler, Lincoln, and Mercedes-Benz applications that use a locking, vented fuel tank cap. It meets OEM specifications and Federal and State emission requirements, with a two-way pressure relief and vacuum relief valve that lets the tank breathe while helping contain fuel vapors.

Key Features

• Lockable design for added fuel tank security
• Regular fuel cap style with shallow cam construction
• Vented anti-surge operation for controlled tank breathing
• Two-way pressure relief and vacuum relief valve
• Thread diameter: 1.5 in.; shell diameter: 2.63 in.; depth: 2.08 in.
• Built to meet OEM specifications and emission requirements
• Gates part number 31691 for direct catalog lookup

Product Details

Gates Regular Locking Fuel Cap 31691 is a direct-fit style cap for vehicles that require a vented, locking fuel tank cap rather than a sealed modern fuel system cap. The vented anti-surge design supports proper tank ventilation while the pressure and vacuum relief valve helps manage fuel vapor control. This makes it a practical replacement for classic truck and passenger car fuel systems, including Ford F-100, F-250, F-350, Bronco, Chevrolet Corvette, and Chevrolet Bel Air applications listed in the fitment data. This part cross-references Four Seasons 35011 for the same application.

The Gates 31691 is also listed across a wide range of interchange references, which helps when matching an original cap number during restoration or maintenance. For buyers searching for a locking fuel cap for 1953-1969 Ford F-Series trucks, 1966-1969 Ford Bronco, or 1958-1963 Chevrolet Impala and Bel Air models, this part number is a strong catalog match.

Common Reasons to Replace

• Lost or damaged locking fuel cap
• Fuel odor caused by a worn cap seal or venting issue
• Difficulty maintaining proper tank pressure or vacuum balance
• Need for a correct replacement on a classic Ford, Chevrolet, or Mercury fuel system
• Restoration work requiring a vented locking cap with the proper shallow cam style

Installation Notes and Tips

Verify thread diameter, shell diameter, depth, and cam style before ordering. This cap is listed for vehicles without evaporative emission systems in several applications, and some fitments note California emission system exclusions or mid/cab tank configurations. Confirm the original cap style and tank neck design on your vehicle before installation. Fits 1953-1969 Ford F-100, 1953-1969 Ford F-250, 1953-1969 Ford F-350, 1966-1969 Ford Bronco, 1958-1963 Chevrolet Impala, and other listed classic applications.

Quality Assurance

Gates states that this locking fuel tank cap meets OEM specifications and Federal and State emission requirements. The vented anti-surge design and two-way relief valve reflect the brand’s focus on controlled fuel system operation for classic vehicle applications.