PLATE 3T9205 - Caterpillar

Fuel Heaters
Fuel heaters prevent the waxing of the fuel, and the plugging of the fuel filters in cold weather. The engine does not dissipate enough heat in order to prevent waxing during cold-weather conditions. There are two types of fuel heaters that can be used: thermostatically controlled and self-adjusting. Heaters that are not thermostatically controlled can heat the fuel in excess of 65 °C (149 °F). High fuel temperatures can have the following effects:
Reduced engine efficiency
Fuel pump damage
Premature wearNote: Never use fuel heaters without some type of temperature regulator. Ensure that fuel heaters are turned OFF during warm-weather conditions.Fuel System Electronic Control Circuit
The fuel system is equipped with an electronically controlled, mechanically actuated unit injector in each cylinder. A solenoid on each injector controls the amount of fuel that is delivered by the injector. An ECM sends a signal to each injector solenoid in order to provide complete control of the engine.There are two major components of the electronic control system that are necessary in order to provide control of the mechanical electronic unit injectors:
ECM
Personality module (storage for the ECM flash file)The ECM is the computer that is used to provide control for all aspects of engine operation. The personality module contains the software that defines the characteristics of the engine control. The personality module contains the operating maps. The operating maps define the following characteristics of the engine:
Horsepower
Torque curves
Engine speed (rpm)
Other characteristicsThe ECM, the personality module, the engine sensors, and the unit injectors work together in order to control the engine. Neither of the four can control the engine alone. The ECM maintains the desired engine speed by sensing the actual engine speed. The ECM calculates the amount of fuel injection needed in order to achieve the desired engine speed.Fuel Injection
The ECM controls the amount of fuel that is injected by varying the signals that are sent to the injectors. The ECM sends a high voltage signal to the solenoid in order to energize the solenoid. The injectors will inject fuel only while the injector solenoid is energized. By controlling the timing and duration of the high voltage signal, the ECM can control injection timing and injection amount.The ECM sets certain limits on the amount of fuel that can be injected. The Fuel Ratio Control (FRC) limit is an adjustment that controls the amount of air and fuel for emission control. This limit is based on the boost pressure. When the ECM senses a higher boost pressure, the ECM increases the FRC limit. The rated fuel position is also a limit that is based on the horsepower rating of the engine. This limit is similar to the rack stops and to the torque spring on a mechanically governed engine. The rated fuel position provides horsepower and torque curves for a specific engine family and for a specific engine rating. All of these limits are programmed into the personality module by the factory. These limits are not programmable by the service technician.Injection timing depends on three factors: the