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| Illustration 1 | g06367383 |
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(1) Fuel cooled injectors
(2) High-pressure system (3) Back-pressure regulator (4) Mono-block (5) Fuel cooler application depended (6) 100 µm strainer (7) Fuel boost pump (8) Primary filter (9) Bypass valve (10) Fuel tank (11) Priming manual or solenoid valve (12) Fuel Transfer Pump (FTP) (13) FTP pressure relief valve (14) Fuel filter group (15) Starting valve (16) System regulator (17) | |
The fuel system for this engine incorporates a low-pressure fuel system and a high-pressure fuel system.
The low-pressure fuel system transfers fuel from the fuel tank to the high-pressure fuel pump. During the transfer of fuel, water is removed from the fuel and the fuel is filtered through a fuel/water separator. The system incorporates a mechanical fuel transfer pump that transfers fuel during engine operation. An electric fuel priming pump is used as a booster pump to increase fuel pressure in the system during engine starting. The fuel transfer pump pushes the fuel through secondary fuel filters prior to reaching the high-pressure fuel pump.
The high-pressure fuel system pressurizes the fuel prior to injection. The fuel is transferred to the injectors through double wall fuel lines. In the case of a leak, the double wall fuel lines provide containment of the high-pressure fuel. For this application, a leak detection system detects fuel leaks from the high-pressure fuel system. The fuel injectors atomize fuel during the fuel injection cycle. Flow limiters limit the total flow of fuel to the injector to a preset level.
The fuel system components form the design of these three engine subsystems:
- Low-pressure fuel system
- High-pressure fuel system
- Electronic control system for fuel delivery
An electric off-engine boost pump supplies fuel from the tank to the on-engine mechanical fuel transfer pump. Fuel is drawn from the tank through a strainer to protect the boost pump from debris. A bypass valve allows fuel to flow around the boost pump to prevent an engine shutdown in the event of a boost pump failure. Fuel then passes through the primary filters. The amount of filtered fuel required by the on-engine fuel system flows to the mechanical fuel transfer pump and the rest recirculates through the priming loop check valve and priming solenoid valve back to the boost pump inlet.
The fuel transfer pump provides a fuel pressure of
When the fuel system has air trapped in the fuel filters, lines, and other fuel system components, the engine could experience difficulty starting. The electric boost pump forces the air that is in the fuel out of the system through the injector cooling circuit.
Priming is required after servicing the fuel system such as changing the fuel filter. Priming is also recommended when the engine has not run for a long time. Refer to Locomotive OEM Operation and Maintenance Manuals for instructions on how to prime the fuel system. During priming, the priming solenoid valve closes delivering full flow to the engine.
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| Illustration 2 | g06082425 |
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(1) Injector
(2) Accumulator-Quill Tube (3) Line Support Clamps (4) High-Pressure Injection Lines (5) Pump to Accumulator High-Pressure Lines (6) High-Pressure junction Block (7) High-Pressure Fuel Pump | |
The common rail high-pressure fuel system on this engine consists of high-pressure fuel accumulator-quill tubes (2) that maintain a volume of fuel that is used to supply each cylinder as needed and high-pressure fuel lines (4) to transport fuel between the high-pressure fuel pump (7), high-pressure accumulator quill tubes (2), and the common-rail injectors (1).
The main components of this system Illustration 2 are between the high-pressure fuel pump (7) and the injectors (1):
- High-Pressure Fuel Pump to Junction Block Lines
- High-Pressure Junction Block
- Accumulator Quill Tubes
- Accumulator Quill to Accumulator Quill Fuel Injection Lines
The low-pressure fuel system provides fuel at the proper pressure, temperature, and cleanliness level to the high-pressure fuel pump. The high-pressure fuel pump pressurizes the fuel to the level required for the engine operating condition. System pressure in the high-pressure fuel system is controlled electronically via a fuel control valve, which regulates the amount of fuel that is allowed to enter the inlet of the pump. A pressure relief valve mounted on the high-pressure pump manifold mechanically limits the maximum fuel pressure in the system in the event of a malfunction.
High-Pressure fuel flows from a manifold on the high-pressure pump (7) to a high-pressure junction block (6), which distributes fuel to each engine cylinder bank via double-walled high-pressures lines (4). The double-wall serves to prevent the escape of any high-pressure fuel in the event of fuel leakage from the high-pressure system and therefore ensures safe containment of the fuel in the event of a high-pressure leak. The fuel is then transported through the high-pressure lines (4), through the accumulator quill tubes (2), and to the injectors (1). If leakage into the double-wall system occurs, the necessary repairs need to be performed as quickly as possible to prevent further damage to the high-pressure fuel system.
Fuel is transported to the modular accumulator-quill tubes via the double-walled injector lines. The modular accumulators contain an integral metallic filter to prevent debris from getting to the injectors and an integral flow limiting device that shuts off flow to the cylinder and prevents over fueling in the event of higher than expected fueling. Refer to Systems Operation, "Accumulator-Quill Tube", for information that is related to the operation of the accumulator-quill tubes.
The accumulator-quill tubes (2) transport high-pressure fuel through each cylinder head directly to electronically controlled injectors (1) that provide the proper injected fuel quantity and timing for the particular operating conditions. Refer to Systems Operation, "Fuel Injector" for information that is related to the operation of the fuel injectors (1).
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| Illustration 3 | g06368411 |
| (1) Fuel Pump | |
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| Illustration 4 | g06108778 |
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(2) Fuel Control Valve
(3) Temperature Sensor - Dry Well Port (4) High-Pressure Manifold (5) Rail Pressure Sensor Port (6) Low-Pressure Mono-Block (7) High-Pressure Pump Inlet (8) Magnetic Oil Drain Plug | |
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| Illustration 5 | g06112996 |
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(9) Double-Wall O-ring
(10) Rail Pressure Sensor | |
Note: The fuel rail pressure sensor is installed into the high-pressure fuel pump. This sensor has an integral crush washer and can only be used one time. Once the sensor is removed from the high-pressure pump, replace with a new sensor.
The common rail fuel system high-pressure fuel pump on this engine is driven by an idler in the engine gear train. The flow of the low-pressure fuel into the high-pressure fuel pump is controlled by the fuel control valve (2). The fuel control valve (2) controls how much fuel is allowed into the pump, which determines the pressure in the high-pressure fuel rail.
The high-pressure pump receives fuel from the fuel transfer pump at
The high-pressure manifold mounted to the top of the pump contains the rail pressure sensor port, dry-well temperature sensor port, pressure relief valve, and the outlet port for high-pressure fuel. The pump also has a low-pressure mono-block (6) on the rear of the pump, which houses low-pressure fuel system valves and regulators and the high-pressure pump fuel inlet port.
Note: The high-pressure manifold (4) and the low-pressure mono-block (6) are not serviceable and do not tamper with and/or disassemble.
Note: If replacing the oil-lubricated high-pressure pump, it may contain residual oil from the performance testing completed at the factory. All oil and fuel connections and passages are plugged/capped with protective covers. Care should be taken to ensure removal of these protective covers upon installation.
Electronic Control System for Fuel Delivery
Fuel delivery is controlled by the ECM and various electric components. The following components are used by the ECM to provide the correct fuel delivery for the engine:
- Electric fuel priming pump
- Engine speed/timing sensors
- Fuel control valve
- Fuel injector solenoids
- Pressure sensors
- Temperature sensors
The ECM receives data that is related to the current engine operating conditions from the various electronic components. The ECM utilizes this data to calculate the correct injection timing and injection duration. A throttle signal is also calculated for the fuel control valve. An injection signal is sent to the fuel injectors to provide fuel delivery to the engine.
Refer to Systems Operation, "Fuel Injector" for information that is related to the operation of the fuel injectors.