ELBOW 6V4363 - Caterpillar

The correct air/fuel ratio is very important for the following considerations:
Margin of detonation
Control of emissions
Achieving optimum service life for the engineIf the air/fuel ratio is not appropriate for the fuel and the operating conditions, a failure of the engine may occur. The service life of the turbocharger, the valves, and other components may be reduced.Fuel Supply Pressure
Fluctuations of the fuel pressure can change the air/fuel ratio. For high pressure gas fuel systems, the maximum fluctuation that is allowed in the fuel pressure to the engine is 3.4 kPa (0.50 psi). For low pressure gas fuel systems, the maximum fluctuation that is allowed in the fuel pressure to the engine is 1.7 kPa (0.25 psi).Gas Pressure Regulator
The gas pressure regulator maintains a pressure differential between the air and the fuel that is supplied to the carburetor. Set the pressure of the fuel supply to a maximum of 1.5 kPa (6 inches of H2O) more than the pressure of the air supply. The gas pressure regulator will maintain the pressure differential in response to changes in the air pressure.A water manometer is used to measure the pressure differential. This measurement is taken when the engine is operating at high idle rpm. When a load is applied, the fuel pressure will usually decrease by approximately 0.25 to 0.5 kPa (1 to 2 inches of H2O). If the performance of the gas pressure regulator is erratic, the gas pressure regulator may require service.Installation Before the Fuel Control Valve
To prevent particles from entering the engine, install a one micron fuel filter 1 m (3 ft) before the gas pressure regulator. The recommended filter is the 4P-4717 Fuel Filter with the 4P-4720 Gas Filter Element.Adjusting the Fuel Pressure
For instructions on adjusting the fuel pressure, refer to Special Instruction, SEHS9769, "Installation and Initial Start-Up Procedure for G3500 Engines".