Gates 31770 Fuel Tank Cap

Gates 31770 Regular Locking Fuel Cap

The Gates 31770 Regular Locking Fuel Cap is a direct-fit fuel tank cap for select Ford and Mercury applications. It is built to meet OEM specifications and emission requirements while helping maintain proper tank pressure control.

As part of the Gates Regular Locking Fuel Cap line, this cap combines a lockable design with emission-control venting and a two-way pressure relief/vacuum relief valve. That means the fuel tank can breathe as needed while helping reduce fuel vapor escape.

Key Features

• Lockable fuel cap design for added security
• Regular fuel cap style with deep cam construction
• Emission-control venting to support evaporative emissions systems
• Two-way pressure relief and vacuum relief valve
• Thread diameter: 1.5 in.
• Shell diameter: 2.63 in.
• Depth: 2.09 in.

Detailed Description

The Gates 31770 fuel tank cap is engineered for vehicles that require a regular locking fuel cap with emission-control functionality. It is listed for applications including 1970-1980 Ford and Mercury models such as Ford Bronco, Ford F-100, Ford F-150, Ford F-250, Ford F-350, Ford E-100 Econoline, Ford Fiesta, and Mercury Capri. This part number, 31770, is also referenced for select evaporative emission system applications and mid-cab tank configurations where noted in the fitment data.

This Gates Regular Locking Fuel Cap line is built to align with OEM specifications and federal and state emission requirements. The deep cam design helps ensure proper engagement, while the pressure relief and vacuum relief valve supports normal tank breathing without allowing fuel fumes to escape unnecessarily.

This part cross-references FEL-PRO 35041 for the same application.

What It Helps Solve

• Loose, missing, or damaged fuel tank cap fitment
• Fuel vapor odor caused by a worn sealing surface
• Check engine or emissions-related issues tied to cap sealing
• Improper tank pressure control in evaporative emission systems
• Security concerns on vehicles using a locking fuel cap

Installation Notes and Tips

Verify the thread diameter, shell diameter, and cam style before installation. Confirm the vehicle’s fuel system configuration, including evaporative emission equipment and any mid-cab tank notes shown in the fitment data. For best results, inspect the filler neck sealing surface for wear or damage before installing the cap.

Fits 1970 Ford F-100, N/A; 1971-1976 Ford Bronco, N/A; 1971-1976 Ford F-100, N/A; 1971-1976 Ford F-250, N/A; 1971-1975 Ford E-100 Econoline, N/A; 1971-1974 Ford F-350, N/A; 1975-1976 Ford F-150, N/A; 1976-1977 Mercury Capri, N/A; 1978-1980 Ford Fiesta, N/A.

Quality Assurance

Gates states that this locking fuel tank cap meets OEM specifications and federal and state emission requirements. The emission-control venting and two-way relief valve design support proper fuel system operation for the listed Ford and Mercury applications.