Mechanical Gas Fuel System G5.9, G8.3 – Engine Runs Rough or Misfires

Electronic fault codes active or inactive

Refer to Section TF for fault code troubleshooting.

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, 013-015, 013-016, or 013-045 and the Ignition System OEM Literature.

Air/fuel ratio is set incorrectly.

Check exhaust excess oxygen against specifications. Adjust if necessary. Refer to the OEM service manual for specifications.

Ignition timing is incorrectly set.

Check the ignition timing against specifications. Adjust as required. Refer to Procedure 013-042.