GRAPPLE AS 4890071 - Caterpillar

Air/Fuel Ratio
The correct air/fuel ratio is 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.Any changes to the air/fuel ratio may affect the exhaust emissions. After adjustment, use an emissions analyzer to measure the exhaust emissions. Ensure that the engine is in compliance with local regulations for emissions.Fuel Supply Pressure
The engine can operate with a minimum fuel pressure of 8 kPa (1.2 psi) for naturally aspirated engines. The engine can operate with a minimum fuel pressure of 83 kPa (12 psi) for turbocharged engines. Fluctuations of the fuel pressure prior to the fuel control valve will have a negative effect on the stability of the engine rpm. Control of emissions can also be affected. Ensure that the engine has a stable fuel pressure of 0.25 kPa ( 0.04 psi).Fuel Temperature
The system is designed for fuel temperatures less than 60 °C (140 °F). For optimum performance, the maximum recommended differential temperature for the fuel and air is 2.8 °C (5 °F).Temperature of the Air Supply
Changes in the temperature of the air supply affect the air/fuel ratio. In addition to seasonal changes, the air temperature changes overnight. Control of the temperature in the engine room will help to maintain the air/fuel ratio.For more information, refer to Application and Installation Guide, LEKQ7250, "Air Intake". Consult your Cat dealer for assistance.Refer to the performance specification for the derate setpoint for ambient temperature.