C6.6 Marine Generator Set Caterpillar

Probable Causes

• Fuel quality

• Quality of oil

• Low engine temperature

• Air intake and exhaust system

• Reduced pressure of intake air

• Excessive valve lash

• Failure of the primary speed/timing sensor

Recommended Actions

Fuel Quality

1. The quality of the fuel that is used in the engine will affect the rate of fuel consumption. Refer to "General Fuel Information" in the Operation and Maintenance Manual, "Refill Capacities".

2. If the fuel is not of an acceptable quality, drain the fuel system and replace the fuel filters. Refill the fuel system with fuel of an acceptable quality. Refer to the applicable sections in the Operation and Maintenance Manual.

3. If the fuel is of an acceptable quality, refer to "Quality of Oil".

Quality of Oil

1. The nominal viscosity of the lubricating oil that is used in the engine will affect the rate of fuel consumption. The viscosity of lubricating oil is defined by the SAE grade of the lubricating oil. The grade of the lubricating oil must be correct for the ambient conditions. Lubricating oil that is intended for use in high ambient temperatures will have a negative effect upon the rate of fuel consumption in cold ambient temperatures. Refer to "Engine Oil" in the Operation and Maintenance Manual, "Refill Capacities".

2. The actual viscosity of the lubricating oil that is used in the engine will change throughout the service life of the oil. Lubricating oil that is heavily contaminated will have a negative effect upon the rate of fuel consumption.

3. If the oil is not of an acceptable quality or if the oil has exceeded the service life, drain the oil system and replace the oil filters. Refill the oil system with oil of an acceptable quality. Refer to the applicable sections in the Operation and Maintenance Manual.

4. If the oil is of an acceptable quality, refer to "Low Engine Temperature".

Low Engine Temperature

1. The operating temperature of the engine will affect the rate of fuel consumption. Operation of the engine below the correct temperature will increase fuel consumption. Failure of the water temperature regulator can prevent the engine from operating at the correct temperature.

2. If the engine operating temperature is low, check the operation of the water temperature regulator. If the water temperature regulator does not operate correctly, a new water temperature regulator must be installed. Refer to Disassembly and Assembly, "Water Temperature Regulator - Remove and Install".

Air Inlet and Exhaust System

Leakage of gas or an increased restriction in either the air intake or the exhaust system can reduce the flow of combustion gas through the engine. A change in the flow of combustion air into the engine adversely affects combustion efficiency and the rate of fuel consumption.

1. Check the air intake system for leakage or restrictions. Refer to Systems Operation, Testing and Adjusting, "Air Inlet and Exhaust System".

2. Check the exhaust system for leakage or restrictions. Refer to Systems Operation, Testing and Adjusting, "Air Inlet and Exhaust System".

3. Repair all defects. Verify that the repair has eliminated the fault.

Reduced Pressure of Intake Air

1. If the pressure of the intake air at the intake manifold is lower than normal, either the speed of the engine will need to be higher or more fuel must be injected in order to produce the same power. Either of these conditions will increase the fuel consumption.

2. Check the pipe from the outlet of the turbocharger compressor to the intake manifold for leaks. If necessary, repair any leaks.

3. Check for the correct operation of the wastegate in the turbocharger. Refer to Testing and Adjusting, "Turbocharger Wastegate - Test".

4. If the turbocharger is suspected as being faulty, replace the turbocharger. Refer to Disassembly and Assembly, "Turbocharger - Remove" and Disassembly and Assembly, "Turbocharger - Install".

Excessive Valve Lash

Excessive valve lash will cause a change in the timing of the opening and closing of the inlet and exhaust valves. Excessive valve lash can cause a reduction of the flow of combustion air into the engine. Reduced flow of combustion air will increase the fuel consumption rate.

Refer to the Troubleshooting Guide, "Excessive Valve Lash".

Failure of the Primary Speed/Timing Sensor

If the primary speed/timing sensor fails, the engine will continue to operate using the signal from the secondary speed/timing sensor on the fuel rail pump. The secondary speed/timing sensor is less precise than the primary speed/timing sensor. Timing differences between the secondary speed/timing sensor and the primary speed/timing sensor may cause an increase in fuel consumption.

1. Use the Caterpillar Electronic Technician (ET) to check for active diagnostic codes that relate to the primary speed/timing sensor.

2. If necessary, replace the primary speed/timing sensor. Refer to Disassembly and Assembly, "Speed/Timing Sensor - Remove and Install".