Mechanical Gas Fuel System G5.9, G8.3 – Engine Speed Surges at Low or High Idle

Engine is cold

Allow the engine to warm up for approximately 1 to 3 minutes. Refer to Procedure 101-004 (Cold Weather Starting) in the Operation and Maintenance Manual B3.9, B4.5, and B5.9 Industrial Series Engines, Bulletin 4021389, or Procedure 101-003 (Cold Weather Operation) in the Operation and Maintenance Manual Automotive, Recreational Vehicle, Bus and Industrial C Series Engines, Bulletin 3810248. Refer to Cold Weather Operation in the Operation and Maintenance Manual NT 855 Engines, Bulletin 3810238, Operation and Maintenance Manual N14 Engine, Bulletin 3666095, or in the Operation and Maintenance Manual, K38 and K50 Series Engines, Bulletin 3810497.

Fuel leak

Check the fuel lines, fuel connections, and fuel filters for leaks using the combustible gas detector service tool. Refer to Procedures 006-063 and 006-064.

Ignition system is malfunctioning or misfiring

Check the ignition system. Refer to Procedure 013-012, 013-014 or 013-016 and the Ignition System OEM Literature.

Throttle plate is malfunctioning

Check the throttle plate for sticking. Refer to a Cummins Authorized Repair Facility.

Engine governor settings are incorrect

Adjust engine governor until acceptable stability and response are achieved. Refer to a Cummins Authorized Repair Facility.