PIPE AS 7C3336 - Caterpillar

Components of the Fuel Injection System
The fuel injection system has the following mechanical components:
Primary filter/water separator
Fuel transfer pump
Electric fuel transfer pump
Secondary fuel filter
Fuel injection pump
Fuel injectors
Fuel manifold
Pressure relief valve
Fuel pressure sensor
Fuel temperature sensor
Water in fuel sensorThe following list contains examples of both service and repairs when priming the fuel system is required:
A fuel filter is changed.
A low-pressure fuel line is replaced.
The fuel injection pump is replaced.
The ECM is replaced, if a fuel cooled ECM is installed.
Draining water from the water separator.For the correct procedure to prime the fuel system, refer to Systems Operation, Testing and Adjusting, "Fuel System - Prime".Engines with a Primary and Secondary Fuel Filter Base
Illustration 3 g06331135
Typical example
The primary and secondary fuel filter base is supplied loose and is mounted to the application.The primary and secondary fuel filter base contains the following components:
Primary filter/water separator
Electric fuel transfer pump
Secondary fuel filterThe primary filter/water separator (1) is supplied with water in fuel sensor (4).The secondary fuel filter (3) is located after the primary fuel filter (1) and the electric fuel transfer pump (2).Fuel Pump Assembly
Illustration 4 g03346818
Typical example
The fuel pump assembly consists of a low-pressure transfer pump (3) and a high-pressure fuel injection pump (1). The pump assembly is driven from a gear in the front timing case at half of the engine speed. The fuel injection pump (1) has two plungers that are driven by a camshaft. The fuel injection pump (1) delivers a volume of fuel three times for each revolution. The stroke of the plungers are fixed.The injector will use only part of the fuel that is delivered by each stroke of the pistons in the pump. The solenoid (2) for the fuel injection pump (1) is controlled by the ECM. This maintains the fuel pressure in the fuel manifold (rail) at the correct level. A feature of the fuel injection pump (1) allows fuel to return to the tank continuously.The fuel injection pump has the following operation:
Generation of high-pressure fuelThe fuel output of the fuel injection pump is controlled by the ECM in response to changes in the demand of fuel pressure.Shutoff
The engine shuts off by preventing the electronic unit injectors from injecting. The ECM then closes the suction control valve to prevent the pressure in the fuel manifold (rail) from increasing.Control
Illustration 5 g03346729
Typical example of the electrical control system for the fuel system
(1) Electronic Control Module (ECM)
(2) Throttle position sensor
(3) Wastegate regulator
(4) Fuel pressure sensor
(5) Engine oil pressure sensor
(6) Inlet manifold pressure sensor
(7) Air inlet temperature sensor
(8) Inlet manifold air temperature sensor
(9) Coolant temperature sensor
(10) Secondary speed/timing sensor
(11) Primary speed/timing sensor
(12) Fuel injection pump
(13) Solenoid for the fuel injection pump
(14) Electronic unit injectorsThe ECM determines the quantity, timing, and pressure of the fuel to be injected into the fuel injector.The ECM uses input from the sensors on the engine. These sensors include the speed/timing sensors and the pressure sensors.The ECM controls the timing and the flow of fuel by actuating