1. Introduction to Fuel Injection
Chapter Lesson 1

2. Gasoline Injection Fundamentals
Uses pressure from an electric fuel pump to spray fuel into the engine’s intake manifold
Provides the engine with the correct air- fuel mixture for specific operating conditions

3. Advantages Improved atomization Better fuel distribution Smoother idle
Improved fuel economy
Lower emissions
Better cold-weather driveability
Increased engine power
Simpler

4. Atmospheric Pressure Formed by the air surrounding the earth
At sea level, the atmosphere exerts psi (103 kPa)

5. Vacuum Lower than atmospheric pressure
Less than 14.7 psi (103 kPa) at sea level
Sometimes called suction

6. Differences in Pressure Cause Flow
An engine uses differences in pressure to force fuel and air into its cylinders
The engine acts as a vacuum pump, producing low pressure, or vacuum, in the intake manifold

7. Intake Manifold Vacuum
Closed throttle, high vacuum
Open throttle, reduced vacuum

8. Engine Throttle Valve
Controls airflow and gasoline engine power output
When opened, airflow, fuel flow, and power increase

9. Gasoline Injection Classifications
There are many types of gasoline injection systems
A gasoline injection system is commonly called a fuel injection system
The two main types of gasoline injection systems used today are Throttle Body and Multiport Injection systems
Some engine manufactures are developing direct fuel injection systems

10. Throttle Body and
Multiport Injection

11. Injectors are mounted in the intake ports going to each cylinder
Throttle Body Injection
Injector nozzles are mounted in a throttle body assembly on top of the engine
Multiport Injection
Injectors are mounted in the intake ports going to each cylinder

12. Indirect Injection
Sprays fuel into the intake manifold. Most gasoline systems are indirect.
Direct Injection
Sprays fuel directly into the engine’s combustion chambers. Used in all diesel injection systems.

13. Gasoline Injection Controls Electronic fuel injection (Main focus)
Hydraulic fuel injection
Mechanical fuel injection
Injection timing
Injector opening relationship

14. Electronic Fuel Injection
Uses various engine sensors and a control module to regulate the opening and closing of the fuel injectors
This is the most common type of gasoline injection system

15. Injection Timing Intermittent injection Timed injection
opens and closes injectors independent of engine intake valves
Timed injection
sprays fuel into the engine just before or as the intake valve opens
Continuous injection
sprays fuel into the intake manifold at all times

16. Injector Opening Relationship
Simultaneous Injection
all the injectors open at the same time
pulsed on and off together
Sequential Injection
injectors open one after the other
injection matches the firing order of the engine

17. Injector Opening Relationship
Group Injection (Bank Injection)
Several but not all injectors open at the same time
V-8 engine–one group of injectors open at one time, another group of four open at a different time