Mechanical Gas Fuel System G5.9, G8.3 – Engine Power Output Low

Verify the complaint

Test the engine operation while under load. Perform an engine acceleration test. Perform an engine load/install test. Refer to the OEM installation instructions.

Load is excessive for engine horsepower rating

Reduce the load on the engine. Refer to OEM specifications.

Engine is misfiring

Refer to the Engine Runs Rough or Misfires symptom tree.

Air intake or exhaust leaks

Inspect the air intake and exhaust systems for air leaks. Refer to the OEM service manual.

Air intake system restriction is above specification

Check the air intake system for restriction. Clean or replace the air filter and inlet piping as necessary. Refer to Procedure 010-031 in the Troubleshooting and Repair Manual B3.9, B4.5, and B5.9 Series Engines, Bulletin 3666087, or Procedure 010-031 in the Troubleshooting and Repair Manual C Series Engines, Bulletin 3666003. Refer to Procedure 3-08 in the Troubleshooting and Repair Manual NT 855 Engines, Bulletin 3810298, Procedure 3-04 in the Troubleshooting and Repair Manual N14 Engine, Bulletin 3666142, Procedure 3-08 in the Troubleshooting and Repair Manual K19 Engine, Bulletin 3810307, or Procedure 3-08 in the Troubleshooting and Repair Manual, K38 and K50 Series Engines, Bulletin 3810432.

Throttle plate is malfunctioning

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

Low or no fuel pressure at the fuel filter (primary pressure)

Increase output pressure from the primary regulator. Refer to Procedure 005-042.

Low or no fuel pressure at the mixer (secondary pressure)

Increase output pressure from the secondary regulator.

Intake manifold pressure (boost) is below specification

Refer to Procedure 010-033 to replace the turbocharger in the Troubleshooting and Repair Manual B3.9, B4.5, and B5.9 Series Engines, Bulletin 3666087, Procedure 010-033 to replace the turbocharger in the Troubleshooting and Repair Manual C Series Engines, Bulletin 3666003. Refer to Procedure 3-13 or 3-14 in the Troubleshooting and Repair Manual NT 855 Engines, Bulletin 3810298, Procedure 3-08 in the Troubleshooting and Repair Manual N14 Engine, Bulletin 3666142, or Procedure 3-13 in the Troubleshooting and Repair Manual, K38 and K50 Series Engines, Bulletin 3810432.