COVER 1566575 - Caterpillar

Illustration 1 g03834040
Fuel system components (typical right side engine view)
(1) Fuel injectors (left side)
(2) Fuel rail pressure sensor
(3) Check valve for the outer wall of the fuel rail
(4) Fuel control valve and controller
(5) Power module (If equipped)
(6) Electric fuel priming pump
(7) Fuel injectors (right side)
(8) Filtered fuel pressure sensor
(9) Temperature sensor for the low-pressure fuel
(10) Manual switch for the electric fuel priming pump
(11) Pressure sensor at the inlet of the fuel priming pump
(12) Temperature sensor for the high-pressure fuel
(13) Unfiltered fuel pressure sensor
(14) Block assembly that contains the in-line high-pressure fuel filterThe fuel system for this engine incorporates a low-pressure fuel system and a high-pressure fuel system into the engine design.The low-pressure fuel system is used to transfer fuel from the fuel tank to the high-pressure fuel pump. During the transfer of fuel, water is removed from the fuel. Also, the fuel is filtered. The system incorporates a mechanical fuel transfer pump that is used to transfer 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 high-pressure fuel system pressurizes the fuel prior to injection. The fuel is transferred to the injectors through double wall fuel lines. The fuel injectors are used to produce atomized fuel during the fuel injection cycle. Flow limiters are used to limit the total flow of fuel to the injector to a preset level.The fuel system is made up of the following components:
Low-pressure fuel lines
Primary fuel filter/water separator
Advanced efficiency secondary fuel filter
Mechanically driven fuel transfer pump
Electric fuel priming pump
Clean Fuel Module (if equipped)
High-pressure fuel pump and fuel control valve
Double wall fuel lines
High-pressure fuel injectors
Electronic control system componentsThese fuel system components form the design of these three engine subsystems:
Low-pressure fuel system
High-pressure fuel system
Electronic control system for fuel deliveryLow-Pressure Fuel System and High-Pressure Fuel System
Illustration 2 g06065314
Low-Pressure Fuel System and High-pressure Fuel system
(15) Outer wall for high-pressure leak collection
(16) Fuel injector
(17) High-pressure fuel lines
(18) Injector bypass
(19) Fuel lines for fuel return flow
(20) Pressure regulator
(21) Orifice
(22) Check valve for fuel return
(23) Fuel tank
(24) Primary fuel filters
(25) Priming pump
(26) Transfer pump
(27) Secondary fuel filters
(28) Tertiary fuel filter
(29) High-pressure fuel pumpLow-Pressure Fuel System
The fuel flows from fuel tank (23) to the mechanical fuel transfer pump (26) and electric fuel priming pump (25). The fuel is drawn through primary filter/water separator (24) prior to being pressurized by the fuel pumps. The electric fuel priming pump is energized during engine starting. Also, the electric priming pump can be used for priming the fuel system. The low-pressure pumps must pressurize the fuel to approximately 250 kPa (36 psi) to open the check valve in the high-pressure fuel pump during engine starting.The fuel then flows through secondary fuel filters (27). After flowing through the secondary fuel filters, the fuel flows into pressure regulator (20). The flow that is not used by high-pressure fuel system is sent back to the inlet of the fuel transfer pump (26). Orifice (21) removes any entrained air from the fuel and returns the