Schley Tools 99100 Cummins 3/4-Inch Fuel Injection Flare Nut Socket 3/8-Drive

The Schley Tools 99100 is a specialty 3/4-inch fuel injection flare nut socket engineered specifically for removing and reinstalling fuel supply lines on late-model Cummins diesel engines. The area surrounding the injection pumps on 4-valve ISC 8.3L and ISB 5.9L engines presents extremely tight clearances that make standard tools impractical — this socket was purpose-built to solve that problem.

Key Features:

• 3/4-inch flare nut design — open-side profile grips the flare nut securely without rounding edges on hardened fuel line fittings
• 3/8-inch square drive — compatible with standard ratchets and extensions for straightforward operation
• Slim, custom profile — engineered to slip into the confined space surrounding Cummins injection pumps where conventional sockets cannot reach
• Slides along the fuel line — socket travels down the line and seats on the flare nut for controlled loosening or tightening
• Dual-purpose use — works for both removal and reinstallation of fuel line nuts when the injection pump is serviced
• Compatible engines: Cummins ISC 8.3L (4-valve), Cummins ISB 5.9L, Detroit Diesel Series 50, and Caterpillar engines
• Not compatible with Cummins ISM engines

Used with a ratchet and extension, this flare nut socket slides along the fuel line and seats firmly on the fitting, allowing technicians to break loose or torque fuel line nuts with minimal effort. Whether in a professional shop or a demanding field-service environment, the Schley Tools 99100 eliminates the frustration of working in tight diesel engine bays.