1. Introduction to Electronic Fuel Systems
Topics covered in this presentation:
Types of Electronic Fuel Systems
Fuel Injection Timing, Open Loop and Closed Loop Modes
Wiring Diagrams and Schematics
ClassAct SRS enabled.

2. Types of Electronic Fuel Systems
Electronic Fuel (petrol) Injection (EFI)
Computer (ECU / ECM / PCM) operates solenoid controlled fuel injectors.
Computer Controlled (feedback) Carburettors
Computer operates mixture control solenoid and/or fuel shutoff valve.
Electronic Diesel Injection
Computer operates fuel metering solenoids.
Electronic Fuel Injection is the most common type of fuel system in use.
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3. Question 1 Which is the most common type of fuel injection system?
A) Electronic Fuel Injection
B) Computer Controlled Carburettors
C) Electronic Diesel Injection
Correct Answer = A

4. Single and Multipoint EFI Systems
Fuel injection systems classified by point of injection.
ECU
Single Point Fuel Injection (Throttle Body Injection - TBI)
Injector located inside throttle body, sits on top of inlet manifold.
Fuel in
Air in
Throttle valve
Injector sprays fuel from above throttle valve.
Injector
Inlet manifold
Throttle body
ECU controls injector opening.
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5. Question 2
In a single-point fuel injection system, where is the injector located?
A) In the inlet manifold
B) Next to the inlet valve
C) Before the air filter
Correct Answer = D
D) In the throttle body

6. Single and Multipoint EFI Systems
Multipoint Fuel Injection
ECU
Injector located in each branch of inlet manifold, below throttle valve.
Fuel in
Air in
Injectors x 4, x6, x8 etc.
Inlet manifold
Throttle valve
Injectors spray fuel directly into each port.
ECU controls opening of injectors.
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7. Question 3
What controls the opening of the injectors in an EFI system?
A) The throttle valve
B) The air pressure
C) The ECU
Correct Answer = C
D) The pressure in the inlet manifold

8. Fuel Injection Timing
Describes when fuel is sprayed into the inlet manifold.
Intermittent (or modulated)
Injectors controlled independently of inlet valve position.
Timed (or sequential)
Injectors controlled in time with inlet valves.
Continuous
Injectors open all the time, fuel pressure is controlled.
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9. Question 4
In which method of fuel injection timing is the fuel supplied in time with the inlet valves?
A) Continuous
B) Sequential
C) Modulated
Correct Answer = B
D) Intermittent

10. Fuel Injector Opening Relationships
Simultaneous Injection (all together).
Sequential Injection (one at a time).
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11. Fuel Injector Opening Relationships
Group Injection
(Injectors of Vee engine operating in A and B banks). A B
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12. ECU Open & Closed Loop Operation
Engine cold, ECU operates in open loop mode.
Uses preprogrammed values to control engine.
Engine at operating temperature, ECU operates in closed loop mode.
It uses data from the oxygen and other sensors to control engine.
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13. Question 5 How many different modes does the ECU operate in?
Enter your answer and press SEND.
Correct Answer = 2

14. Typical Fuel System Sub-Systems
1. Fuel Supply System
Supplies clean fuel to fuel metering system (fuel pump, filters, pipes).
2. Air Supply System
Supplies controlled clean air to engine (air filter, ducting).
3. Fuel Metering System
Controls amount of fuel (and air) entering engine (injectors, pressure regulator, throttle valve).
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15. Fuel System Diagrams and Schematics
Fuel System Block Diagrams - 1
System and subsystem
blocks
Each block represents a system.
Lines represent connections between systems.
Arrows represent direction of flow.
Direction of
information
flow/control
Connection lines
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16. Fuel System Diagrams and Schematics
Fuel System Block Diagrams - 2
System and component
blocks
Connection lines
Each block represents a component.
Lines represent connections between systems.
Arrows represent direction of flow.
Direction of
information
flow/control
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17. Fuel System Diagrams and Schematics
Fuel System Schematic Diagrams
Wiring
Components
Fuel pipes
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18. Question 6 Fuel system schematic diagrams show: 1. Components
2. Fuel pipes
3. Wiring
4. Connector numbers
Which of these are correct?
Correct Answer = C
A) 1, 2 and 4
C) 1, 2 and 3
B) 2, 3 and 4
D) 1, 3 and 4

19. Fuel System Diagrams and Schematics
Fuel System Wiring Diagrams
Wire size
Connector number
Component symbol
Wire colour
Wire
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20. Question 7
Fuel system wiring diagrams show wire size, wire colour and wire connector number. Is this true or false?
Answer True or False.
Correct Answer = T

21. Summary You should be aware of: Types of Electronic Fuel Systems
Fuel Injection Timing, Open Loop and Closed Loop Modes
Wiring Diagrams and Schematics
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