0431677 JOHNSON GEARCASE ASSY., Complete

Illustration 1 g06094876The fuel flows from the main gas supply through a knock-down regulator. A knock-down regulator is a second regulator that is needed when the gas supply pressure is too high for a single regulator to manage.From knock-down regulator, the fuel flows to the fuel filter. Usually, the fuel filter is a component of the design at the particular site. The customer is responsible for supplying clean, dry fuel to the engine. The fuel filter may be supplied by Caterpillar or by the customer. To prevent particles from entering the engine, a 1 micron filter is recommended. Select a filter that is properly sized for the required gas pressure.For installation of the fuel filter, the recommended location is close to the engine before the engine's gas pressure regulator. Pressure gauges in the gas lines on each side of the fuel filter are recommended to monitor the filter's differential pressure. A manual shutoff valve in the gas line before the fuel filter will facilitate servicing of the filter.The filtered fuel flows to the Gas Shutoff Valve (GSOV). The GSOV (3) is supplied by Caterpillar or by the customer. The solenoid for the GSOV is connected to the engine's wiring harness.The control system is configured for a GSOV that is energize-to-run. This means that the GSOV must be energized in order for the engine to run. This means that the GSOV must be energized in order for the engine to run. When the GSOV is energized, the valve opens and the fuel flows to the engine. When the control system shuts down the engine, the voltage is removed from the solenoid. The valve closes and the fuel is shut off.The fuel flows through the GSOV to the gas pressure regulator (2).The regulator is supplied by Caterpillar.The required fuel pressure stability is 1.7237 kPa ( 0.25 psi).A regulated pressure of 7 to 35 kPa (1 to 5 psi) is recommended. For engines experiencing hard starting, a regulated pressure of 7 to 17 kPa (1 to 2.5 psi) is recommended.Less gas pressure may result in reduced power. More gas pressure may result in instability.
Illustration 2 g06095288
(1) Fuel Metering Valve
(2) Gas Pressure Regulator
(3) Gas Shut-Off Valve (GSOV)The fuel flows to the electronically controlled fuel metering valve (1). The ECM issues a command signal to the fuel metering valve via the Controller Area Network (CAN) data link. The fuel metering valve regulates the flow of fuel to the engine.
Illustration 3 g06095379
(4) Fuel Metering Valve
(5) Air Inlet Elbow
(6) TurbochargersThe fuel metering valve (4) controls the volume of fuel that flows to adapter for the air inlet elbow (5). The inlet air that is necessary for combustion also enters the adapter. The air/fuel mixture enters turbocharger compressor (6).
Illustration 4 g06095381
(7) Aftercooler
(8) ThrottleThe temperature of the compressed air/fuel is reduced in the aftercooler (7) resulting in an increased density of the air/fuel mixture. This results in more efficient combustion.The dense air/fuel mixture flows to the electronically controlled throttle (8). The ECM issues a command signal to the actuator for the throttle via the CAN data link. The signal is based on the desired engine speed. The throttle controls the volume of the air/fuel mixture that flows through aftercooler (7).The air/fuel mixture flows from the throttle (8) through air inlet manifold, through the spark arrestors, to the cylinders for combustion.