ELECTRONICS GP-MONITOR 3601839 - Caterpillar

Fuel System Operation
The transfer pump (18) pulls fuel from the fuel tank (7) through the 10 micron primary fuel filter (12). Transfer pump (18) sends the fuel through the 4 micron secondary fuel filter and the 4 micron tertiary fuel filter to high-pressure fuel pump (19). Fuel pressure sensor (16) measures the fuel pressure at the inlet of the secondary fuel filter. Fuel pressure sensor (14) measures the fuel pressure that is entering the tertiary filter. The high-pressure fuel pump (19) pressurizes the fuel that is sent to the fuel rail (4). The fuel rail (4) distributes the fuel to the fuel injectors (2) by the use of fuel lines. The fuel rail uses a fuel pressure sensor (3) that tells the ECM (13) about the pressure of the fuel rail. The ECM receives engine speed from the speed/timing sensor (17). The ECM controls the solenoids for the high-pressure fuel pump to obtain the correct amount of pressure. If pressure at the fuel rail is too high, the pressure relief valve (5) opens. This valve opening drains the excess fuel back to the fuel tank. The rail pressure can vary from 42 MPa to 190 MPa. Once the fuel reaches the injectors, ECM sends current to the injector solenoid to actuate the three-way valve inside the injector. As the valve opens, the fuel flows from the high-pressure line to the tip. As the valve opening pressure is reached, the check is lifted and fuel is delivered at high pressure into the combustion chamber. The fuel is then delivered in a precise quantity and at the right time. The injector bypasses the excess fuel to the tank through check valve (8) and pressure regulator (6).Component Description
Engine Control Module (ECM)
Illustration 2 g06236291
A6:E2 ECM
Engine Control Module (ECM) is on the left side of the engine. The ECM is a powerful computer that provides total electronic control of engine performance. The ECM uses data from engine performance that is gathered by several sensors. Then, the ECM uses this data to adjust the fuel delivery, injection pressure, and injection timing. The ECM contains programmed performance maps (software) to define horsepower, torque curves, and rpm. This software is commonly called the personality module.The engine does not have a replaceable personality module. The personality module is a permanent part of the ECM. The personality module for the engine can be reprogrammed by Cat® Electronic Technician (ET).ECM logs faults of engine performance. Also, the ECM can run several diagnostic tests automatically when the ECM is used with an electronic service tool such as the Cat ET.Priming Pump
Illustration 3 g06236499
(1) Electronic Fuel Priming PumpThe electric priming pump (1) forces the air that is in the fuel out of the system through the orifice on the regulator. Priming usually takes place after servicing the fuel system such as changing the fuel filter. This mode can also occur when the engine has not run for a long period. When the fuel system has air trapped in the fuel filters, lines, and