Page 129 - Mechanic Diesel - TT

MECHANIC DIESEL - CITS

Combustion process of Diesel fuel:
1 In a diesel engine, air is compressed under high pressure and temperature in the combustion chamber.
2 Diesel fuel is injecting directly into the combustion chamber.
3 The high temperature and pressure of the compressed air ignites the diesel fuel without the need for a spark.

4 The combustion of diesel fuel releases energy, which pushes the piston down, thereby propelling the vehicle.
5 Diesel fuel is produced in the form of carbon dioxide (CO2), water vapour (H2O), nitrogen oxides (NOx), and
particulate matter.

Study about conventional diesel fuel system and its

components such as fuel tank, fuel feed Pump, electrical
pump, fuel filters, water separators, fuel injection pumps,

governors, injectors etc. Importance of maintenance,

diagnosis and Servicing diesel fuel system and its
components. Causes of failure of the diesel fuel system

and its components

Objectives: At the end of this lesson you shall be able to
• understand about conventional diesel fuel system and its components
• explain Importance of maintenance, diagnosis and Servicing diesel fuel system and its components
• demonstrate Causes of failure of the diesel fuel system and its components.

Study about conventional diesel fuel system
A conventional diesel fuel system typically consists of components like the fuel tank, fuel lines, fuel filter, fuel
pump, fuel injectors. The system delivers diesel fuel from the tank to the engine’s combustion chambers, where
it mixes with air and ignites under compression to generate power. The fuel filter ensures that the fuel entering
the engine is free from contaminants, while the fuel pump pressurizes the fuel for efficient injection into the
combustion chambers via the fuel injectors. Additionally, modern diesel engines often employ electronic control
systems to optimize fuel delivery for improved performance and emissions.
Components of conventional diesel fuel system

• Fuel tank: The Fuel tank is provided for storing diesel required for running the engine. It is constructed
of either pressed sheet metal with welded seams and special coating to prevent corrosion or fiber glass
reinforced plastic materials. It may be round or rectangular in shape. It is mounted above the engine assembly.
• Fuel pipe: Fuel pipe between the fuel tank and the feed pump is called suction pipe, the pipes between F.I.P.
and the injectors are called high pressure pipes. An over flow pipe is provided on fuel filter bowl and injectors
to supply excess fuel back to fuel tank.
• Fuel filter: Fuel filter assembly is used in between feed pump and fuel pump. It’s used for cleaning diesel fuel
and separate the water from the fuel.
• Fuel feed pump: A feed pump is usually mounted on the F.I.P. and is driven by the camshaft of F.I.P. It sucks
fuel from fuel tank and supplies it to fuel filters.
• Fuel injection pump: Fuel Injection Pumps are designed to deliver specific quantity of fuel to the combustion
chamber through an injector at a specific time.
• Governors: The governor is a device for holding any speed steady between idling and maximum speed. The
fuel injection pump operates in conjunction with a governor, which is required to control the injected quantity
of fuel so that the engine neither stalls when idling nor exceeds the maximum speed for which it is designed.

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CITS : Automotive - Mechanic Diesel - Lesson 31 - 38