12.14.8(c) . fuel injectors. 

– with indirect injection, fuel injectors spray the fuel into the inlet manifold.
– with direct injection fuel injectors spray fuel directly into the cylinder.

12.14.8(b) . fuel distribution system; 

– fuel is distributed through a fuel control unit which senses throttle postion, mixture setting and airflow the meter the correct amount of fuel to the injectors.

12.14.8(a) . fuel delivery pump system; 

– most systems have a fuel pump and a boost pump system.
– as well as being a back-up, the boost pump is used the prime the engine for starting and preventing vapour lock problems.

12.14.8. State the purpose of the following components in a basic fuel injection system:

12.14.6. Explain the operating principle of a simple fuel injection system.

Fuel Injection System
– Continuous flow system
– a throttle valve controls the amount of air going to make up the mixture for the engine – and therefore the power developed
– a fuel control unit senses the mass of air entering the engine and the position of the throttle and mixture controls
– from this data the pressure output of the injection pump is varied so as to meter the correct amount of fuel required for the mixture
– metered fuel passes through a flow divider or splitter and then through individula lines to the injection nozzles associated with individual cylinders
– fuel is then injected continuously into the airflow as a high presure spray to form the mixture

12.14.4(b) . difference between direct and indirect injection. Sub Topic Syllabus Item 

Direct
– fuel is injected at a much higher pressure direclty into the combustion chamber of each cylinder. (normally only diesel engines)

Indirect
– fuel is injected into and mixed with the airflow in the inlet manifold at some point prior to each inlet valve
–

12.14.4(a) . function and principles of a fuel injection system; 

Fuel Injection System
– Continuous flow system
– a throttle valve controls the amount of air going to make up the mixture for the engine – and therefore the power developed
– a fuel control unit senses the mass of air entering the engine and the position of the throttle and mixture controls
– from this data the pressure output f the injection pump is varied so as to meter the correct amount of fuel required for the mixture
– metered fuel passes through a flow divider or splitter and then through individula lines to the injection nozzles associated with individual cylinders
– fuel is then injected continuously into the airflow as a high presure spray to form the mixture

12.14.4. Explain the:

12.14.2. State the advantages/disadvantages of fuel injection versus carburetor systems.

Fuel Injected Systems
Advantages:
– Freedom from refrigeration ice.
– Better control and distribution of fuel mixture .
Disadvantages:
– Possibility of vapour lock when starting a hot motor.
– susceptable to contamination problems.

12.12. Carburation