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1106 Perkins Diesel Engine - Fuel Injection
Diagram of the basic fuel system - (1) Electronic Unit Injector (2)
Solenoid for the fuel injection pump (3) Wastegate Valve (if equipped)
(4) Secondary Speed/Timing Sensor (5) Fuel Injection Pump (6) Primary
Speed/Timing Sensor (7) Intake Manifold Pressure Sensor (8) Fuel
Manifold Pressure Sensor(9) Engine Oil Pressure Sensor (10) Intake
Manifold Temperature Sensor (11) Coolant Temperature Sensor (12)
Diagnostic Connector (13) Engine Electronic
Control Module (ECM)
Low Pressure Fuel System
Low pressure fuel system - (1) Primary fuel filter (2) Water separator
(3) Fuel transfer pump (4) Fuel cooler (optional) (5) ECM (6) Secondary
fuel filter (7) Fuel Injection Pump (A) Outlet for High pressure fuel to
the high pressure fuel manifold (B) Return from the Pressure Relief
Valve on the High pressure fuel manifold (C) Return to Fuel tank (D)
Return from the Electronic Unit Injectors (E) Fuel in from the Fuel Tank
Fuel is drawn from the fuel tank (E) through a 20 micron Primary fuel
filter (1) and the Water separator (2) to the Transfer pump (3). The
transfer pump increases the fuel pressure to 25 kPa (3.6260 psi). The
fuel is pumped through the fuel cooler (optional) (4) to the ECM (5).
The fuel cools the Electronic Control Module. The fuel passes from the
1106 Perkins engine ECM to a 2 micron fuel filter (6). The fuel filter
removes particulates from 20 microns to 2 microns in size in order to
prevent contamination of the high pressure components in the fuel
system.
Fuel passes from the fuel filter to the fuel injection pump (7). The
fuel is pumped at an increased pressure to the high pressure fuel
manifold. Excess fuel from the high pressure fuel pump returns to the
tank through a non-return valve. There is a small orifice in the fuel
filter base in order to bleed any air back to the tank. The leak off
fuel from the electronic unit injectors returns from a connection in the
cylinder head to the pressure side of the transfer pump.
High Pressure Fuel System
High pressure fuel system - (1) Electronic Unit Injector (2) High
Pressure Fuel Manifold (3) Fuel Pressure Sensor (4) Fuel Pressure Relief
Valve (5) Fuel Transfer Pump (6) Solenoid for the Fuel Injection Pump
(7) Fuel Injection Pump (8) Fuel Pump Gear
The fuel injection pump (7) feeds fuel to the high pressure fuel
manifold (2). The fuel is at a pressure of 70 MPa (10152.7 psi) to 130
MPa (18855 psi). A pressure sensor (3) in the high pressure fuel
manifold (2) monitors the fuel pressure in the high pressure fuel
manifold (2). The engine ECM controls a solenoid (6) in the fuel
injection pump (7) in order to maintain the actual pressure in the high
pressure fuel manifold (2) at the desired level.
The high pressure fuel is continuously available at each injector. The
1106 Perkins engine ECM determines the correct time for activation of
the correct electronic unit injector (1) which allows fuel to be
injected into the cylinder. The leakoff fuel from each injector passes
into a drilling which runs along the inside of the cylinder head. A pipe
is connected to the rear of the cylinder head in order to return the
leak off fuel to the pressure side of the fuel transfer pump.
Components of the Fuel Injection System
The fuel injection system has the following mechanical components:
Primary filter/water separator, Fuel priming pump, Secondary fuel
filter, Fuel injection pump, Fuel injectors, Fuel manifold, Pressure
relief valve, Fuel pressure sensor. The following list contains examples
of both service and repairs when you must prime the system: A fuel
filter is changed. A fuel line is replaced. The fuel injection pump is
replaced.
Primary Filter/water Separator - The primary filter/water separator is
located between the fuel tank and the priming pump.
Hand Fuel Priming Pump - The pump has a plunger (1) which is manually
operated in order to prime the fuel system. Air is removed from the fuel
system to the fuel return line to the tank. The fuel transfer pump is
located in the fuel injection pump.
Electric Fuel Priming Pump - The electric fuel priming pump can be
installed on some Perkins engines.
Secondary Fuel Filter - The secondary fuel filter (1) is located after
the priming pump. The filter is always before the fuel injection pump.
Fuel Pump Assembly - The fuel pump assembly consists of a low pressure
transfer pump and a high pressure fuel injection pump. The pump assembly
is driven from a gear in the front timing case at half engine speed. The
fuel injection pump has two pistons that are driven by a camshaft. There
is a cam for each piston and each cam has three lobes. The fuel
injection pump delivers a volume of fuel six times for each revolution.
The stroke of the pistons is fixed. The injector will use only part of
the fuel that is delivered by each stroke of the pistons in the pump.
The solenoid for the fuel injection pump is controlled by the motor ECM
in order to maintain the fuel manifold pressure at the correct level.
The solenoid allows excess fuel to be diverted away from the fuel
manifold and back to the tank. A feature of the fuel injection pump
allows fuel to return to the tank continuously.
Fuel Injection Pump - The fuel injection pump has the following
operations: Generation of high pressure fuel. The fuel output of the
fuel injection pump is controlled by the ECM in response to changes in
fuel pressure.
Fuel Transfer Pump - The fuel transfer pump is a serviceable component.
The fuel transfer pump provides a relatively low fuel pressure to the
fuel injection pump. The fuel transfer pump has a regulating valve in
order to control the low pressure. The fuel transfer pump circulates
fuel through the primary fuel filter and the secondary fuel filter. The
fuel transfer pump has a fuel bypass valve in order to allow the low
pressure fuel system to be primed.
Shutoff - The engine shuts off by interrupting the fuel supply. The
engine electronic control module (ECM) specifies the amount of fuel. The
quantity of the fuel that is required by the ECM is set to zero.
Electronic control for the fuel system - The motor Electronic Control
Module determines the quantity, timing and pressure of the fuel in order
to be injected into the fuel injector. The Electronic Control Module
uses input from the sensors on the engine. These sensors include the
speed/timing sensors and the pressure sensors. The ECM controls the fuel
pressure by increasing or decreasing the flow of fuel from the fuel
injection pump. The ECM controls the timing and the flow of fuel by
actuating the injector solenoid. The amount of fuel is proportional to
the duration of the signal to the injector solenoid.
Fuel Injectors - The fuel injectors are not serviceable. When the 1106
Perkins engine ECM sends a signal to the injector solenoid, a valve
inside the injector opens. The valve allows the high pressure fuel from
the fuel manifold to enter the injector. The pressure of the fuel pushes
the needle valve and a spring. When the force of the fuel pressure is
greater than the force of the spring, the needle valve will lift up. The
timing and duration of injection is controlled by a solenoid valve in
the injector. The valve has two positions. In the closed position, the
valve closes the inlet to the injector. In this position, fuel above the
injector needle is allowed to vent through the leak off port. In the
open position, the valve opens the inlet to the injector.
Simultaneously, the valve closes the leakoff port in order to allow high
pressure fuel to flow to the needle.
When the solenoid valve is closed, some fuel escapes past the valve in
order to vent through the leakoff port. A certain volume of fuel always
flows from the leakoff port. If the volume of fuel increases beyond a
critical level, the high pressure fuel pump will not be able to maintain
pressure in the fuel manifold. The faulty electronic unit injector must
be identified and replaced. When the signal to the injector ends, the
valve closes. The fuel in the injector changes to a low pressure. When
the pressure drops the needle valve will close and the injection cycle
stops. When the needle valve opens, fuel under high pressure will flow
through nozzle orifices into the cylinder. The fuel is injected into the
cylinder through the orifices in the nozzle as a very fine spray. The
needle valve has a close fit with
the inside of the nozzle. This makes a positive seal for the valve.
Fuel Manifold - The fuel manifold (1) stores high pressure fuel from the
fuel injection pump. The high pressure fuel will flow to the injectors.
The fuel pressure sensor (2) measures the fuel pressure in the fuel
manifold (1). The relief valve (3) will prevent the fuel pressure from
getting too high.
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