0392375 JOHNSON FLOAT CHAMBER ASSY.,Upper

Fuel System (Air/Fuel Ratio Control)
The fuel system includes these components:
Engine control module (ECM)
Fuel metering valve
Atmospheric Pressure Sensor
Humidity Sensor
Inlet manifold pressure sensor
Inlet manifold temperature sensor
NOX sensorThe fuel metering valve controls the flow of fuel to the engine. The ECM determines the requirement for the mixture of air and fuel. The ECM sends a signal to the fuel metering valve. The fuel metering valve controls the volume of the gas flow to the engine.A NOX sensor measures the NOX content in the exhaust gas. The inlet manifold pressure and temperature are monitored. This information is provided to the ECM. The ECM uses this information to adjust the flow of fuel in order to meet emissions requirements. This process is continuous during engine operation.The fuel flows through the fuel metering valve into the mixer. The mixture of air and fuel flows through the turbocharger compressor. The air/fuel mixture is cooled in the aftercooler. The mixture enters the cylinders through a throttle valve.The ECM sends a signal to the throttle valve. The throttle controls the flow of the air/fuel mixture to the cylinders.Ignition System
The engine is equipped with an electronic ignition system. The system provides dependable firing and low maintenance. The system provides precise control of the spark and the ignition timing for each cylinder.The system also provides diagnostic capability that enhances troubleshooting. The primary ignition wiring is routed internally through the engine.The engines are equipped with protection from detonation. A detonation sensor is located between every two cylinders. The ignition timing is retarded for a cylinder when excessive detonation is sensed in that cylinder. If the maximum retarded position is attained and detonation continues to occur, the ECM shuts down the engine.The engines are equipped with flame arresters. The flame arresters are located at the entrance of each inlet port. If the engine backfires, the flame arresters prevent the fire from entering the air/fuel mixture.Lubrication System
The engine lubrication oil is circulated by a gear-driven pump. The oil is cooled and filtered. A bypass valve provides unrestricted flow of lubrication oil to the engine parts if the oil filter elements become plugged.The engine also has a turbocharger oil accumulator. This accumulator provides oil to the turbocharger during hot shutdowns and during start-up.Cooling System
The standard cooling system has a gear-driven centrifugal pump. For applications that combine heating and power, the pump for circulating the jacket water is supplied by the customer. The cooling system has temperature regulators that regulate the temperature of the coolant. The temperature depends on the application.The turbocharged engine has a two-stage aftercooler. The first stage is a jacket water cooler, and the second stage is a Separate Circuit Aftercooler (SCAC). The SCAC is required to operate at 54 °C (130 °F).If the inlet temperature to the SCAC exceeds these temperatures, consult your Caterpillar dealer.Engine Service Life
Engine efficiency and maximum utilization of engine performance depend on adherence to proper operation and maintenance recommendations. This adherence includes the use of recommended lubricants, fuels, and coolants.For the engine maintenance that is required, refer to this Operation and Maintenance Manual, "Maintenance Interval Schedule" (Maintenance Section).