3176C, 3406E and 3456 Industrial Engines Troubleshooting – Fuel Consumption Is Excessive

Probable Causes

Engine Operation


  • Look for excessive idle or high load 

Fuel Supply


  • Unstable fuel supply 

Engine Speed/Timing


  • Calibration procedure of the engine speed/timing 

Fuel Injection System


  • Unstable injection system 

Air Inlet and Exhaust System


  • Restriction in the air inlet and exhaust 

Accessory Equipment


  • Check for damaged accessory equipment 

Recommended Actions

Look for Excessive Idle or High Load

Use Caterpillar Electronic Technician (ET) to check the “Current Totals” for excessive idle time and/or for a high load factor which would be indicative of poor operating habits.

Unstable Fuel Supply

Visually check the fuel level. Do not rely on the fuel gauge only. If necessary, add fuel. If the engine has been run out of fuel, it will be necessary to purge the air from the fuel system. Refer to the Operation and Maintenance Manual.

Ensure that the fuel supply valve (if equipped) is in the full OPEN position.

Check fuel lines for the following problems: restrictions, collapse and pinched line. Repair the lines and/or replace the lines.


  1. Check the fuel tank for foreign objects which may block the fuel supply. Check for air leaks in the suction line of the fuel pump. Purge the fuel system after you perform the following procedures: 
    • Replacing the fuel filters 
    • Working on the low pressure fuel supply circuit 
    • Replacing fuel injectors 


  1. Cold weather adversely affects the characteristics of the fuel. Refer to the Operation and Maintenance Manual for information on improving the characteristics of the fuel during cold weather operation.


  1. Check the fuel pressure during engine operation. Check the fuel pressure after the fuel filter. Refer to the Systems Operation/Testing and Adjusting manual for the correct pressure values. If the fuel pressure is low, replace the fuel filters. If the fuel pressure is still low, check the following items: fuel pump, pump coupling and fuel pressure regulating valve.

Calibration Procedure of the Engine Speed/Timing

Perform a speed/timing sensor calibration. Refer to the calibration procedure Troubleshooting, “Timing – Calibrate”.

Unstable Injection Actuation System


  1. Check for correct installation of the J1/P1 and J2/P2 Electronic Control Module (ECM) connectors and the injector connectors. Refer to Troubleshooting, “Electrical Connectors – Inspect”.


  1. Perform the “Injector Solenoid Test” on Cat ET in order to determine if all of the injector solenoids are being energized by the ECM.


  1. Perform the “Cylinder Cutout Test” on Cat ET in order to identify any injectors that might be misfiring. Refer to Troubleshooting, “Injector Solenoid – Test”.

Restriction in the Air Inlet and Exhaust


  1. Inspect the air filter for a restriction. If the air filter shows signs of being plugged, clean the air filter or replace the air filter.


  1. Check the air inlet and exhaust system for restrictions and/or for leaks. Refer to Systems Operation/Testing and Adjusting.

Check for Damaged Accessory Equipment

Check all accessory equipment for problems that may create excessive load on the engine. Repair any damaged components or replace any damaged components.

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