Introduction
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| Illustration 1 | g01626847 |
Fuel system diagram (1) Solenoid for the fuel pump (2) High pressure supply line (3) Fuel injector (4) Fuel pressure sensor (5) Fuel rail (6) Pressure relief valve for the fuel rail (7) Quill tube (8) Pressure regulator for the drain line (9) Fuel return line back to tank (10) Fuel tank (11) Primary fuel filter (12) Electronic control module (ECM) (13) Secondary fuel filter (14) Transfer pump (15) Fuel pump (16) Speed/timing sensor (17) Pressure relief valve for the fuel pump | |
The operation of this fuel system is completely different from any other type of fuel system that is actuated mechanically. The fuel system is completely free of adjustment. Adjustments to the components that are mechanical can not be made. Changes in performance are made by installing different software on the Electronic Control Module (ECM) (12) .
This fuel system consists of five major components:
- Fuel pump (15)
- Electronic Control Module (ECM) (12)
- Fuel Injectors (3)
- Fuel rail (4)
- Fuel transfer pump (14)
Note: The components of the fuel system are not serviceable. These fuel system components must not be disassembled. Disassembly will damage the components. If the components have been disassembled, Caterpillar may not allow a warranty claim or Caterpillar may reduce the warranty claim.
Fuel System Operation
Fuel is pulled from the fuel tank (10) and through the primary fuel filter (11) by the use of the transfer pump (14). The transfer pump (14) sends the fuel through the secondary fuel filter (13) and up to the fuel pump (15). The fuel pump (15) pressurizes the fuel that is sent to the fuel rail (5). The fuel rail (5) distributes the fuel to the fuel injectors (3) by the use of quill tubes (7). The fuel rail uses a fuel pressure sensor (4) that tells the ECM (12) the pressure of the fuel rail. The ECM also receives engine speed from the speed/timing sensor (16). The ECM controls the solenoids for the fuel pump (1) in order to obtain the correct amount of pressure. If pressure at the fuel rail is too high, the pressure relief valve (6) will drain proper amounts of fuel back to the fuel tank. Once the fuel reaches the fuel injectors, the fuel injectors open a control valve that is inside of the injector by the use of a solenoid. The fuel injectors deliver the high pressure fuel into the combustion chamber at precise amounts of quantity and time. A drain in the fuel injector sends fuel that was not used during the delivery to the secondary filter. The pressure regulator (8) keeps a constant back pressure on the fuel injector.
Component Description
Fuel Injector
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| Illustration 2 | g01173131 |
Side view (1) Solenoid (2) Control valve (3) Drain hole (4) Quill tube bore (5) Tip | |
The fuel system utilizes electronic controlled fuel injectors. This system uses electronically actuated solenoids (1) to control the injection of the fuel into the combustion chamber.
The injector uses a control valve (2) in order to control the delivery of fuel into the combustion chamber. The drain hole (3) sends unused pressurized fuel back to the secondary fuel filter. The other pressurized fuel is injected through orifice holes in the bottom of the tip (5). Fuel is inserted into the combustion chamber in precise amounts in order to control engine performance.
There are many other operating conditions when the injection pressure is between the minimum and the maximum. Regardless of the speed of the engine, the fuel system provides complete control of injection pressure.
Quill Tube
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| Illustration 3 | g01173279 |
Side view (6) Quill tube (7) Ball (8) O-ring seal (9) Nut | |
The quill tube (6) fits on the inside of the cylinder head. The quill tube is held in position by the use of a nut (9) and a ball (7). An O-ring seal (8) is used in order to help seal the quill tube in the head. Refer to Specifications, "Fuel Injector" for the proper installation of the quill tube.
Electronic Control Module (ECM)
Electronic Control Module (ECM) is located 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 in order to make adjustments to the fuel delivery, injection pressure and injection timing. The ECM contains programmed performance maps (software) in order 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 Caterpillar Electronic Technician (ET).
ECM logs faults of engine performance. Also, the ECM is capable of running several diagnostic tests automatically when the ECM is used with an electronic service tool such as the Cat ET.
Fuel Pump
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| Illustration 4 | g01171732 |
(10) Fuel pump | |
Fuel pump (10) is located at the left front corner of the engine. The fuel pump uses electronic solenoids and RPM from the engine to pressurize the fuel.
Fuel Transfer Pump
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| Illustration 5 | g01171756 |
(10) Fuel pump (11) Fuel transfer pump | |
Fuel transfer pump (11) is mounted on the back of fuel pump (10). The fuel is pressurized to 190 MPa (27550 psi).
The fuel transfer pump is a variable gear pump. The fuel transfer pump is driven by the shaft of the fuel pump. A relief valve in the fuel transfer pump limits the outlet pressure to 1950 ± 100 kPa (280 ± 15 psi).
Rail Pressure Sensor (RPS)
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| Illustration 6 | g01173232 |
(12) Rail Pressure Sensor | |
Rail pressure sensor (12) is installed in the high pressure fuel rail. The rail pressure sensor monitors the fuel pressure that is inside of the fuel rail. The rail pressure sensor sends a analog voltage signal back to ECM. The ECM interprets the signal. The ECM is aware of the fuel pressure at all times.