Page 148 - Mechanic Diesel - TT

MECHANIC DIESEL - CITS

Importance of bleeding the 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.

Parts of the fuel tank
• Filler neck and cap
• Baffle
• Fuel gauge sensing unit (Float)
• Filter

• Sediment bowl and drain plug
Filler neck is provided for pumping diesel into the fuel tank. A cap is provided for closing the tank tightly. A vent
hole is provided either in filler neck or in cap to maintain atmospheric pressure in the tank above the fuel.
Bleeding of the fuel system

Bleeding is the process by which air, which is present in the fuel system, is removed. Air locking in the fuel system
will result in erratic running of the engine and may result in stopping of the engine. Bleeding is carried out by
priming the filter.
A slight loosening of the bleeding screw allows locked air to escape as bubbles along with the fuel.
When locked air escapes and the system is free of air, the screw is tightened finally.

Importance of fuel system
When you maintain your vehicle, it is important to have parts and components checked regularly. The function of
the fuel system is to store and supply fuel to the engine and cylinder chambers. There, it can be mixed with air,
vaporized, and then burned to produce the energy. The fuel pump will draw the fuel from the tank, have it travel
through the fuel lines, and then is delivered through a fuel filter to the injectors. It is then delivered to the cylinder
chamber for combustion. When your vehicle accomplishes this process, then your engine will run.
Trouble shooting in diesel fuel system and its components
faults occurring in diesel fuel system and their solutions are shown in the table below.

1 Fuel Tank
Causes Remedy
Leakage of fuel Repair the fuel Tank
Blockage EVAP system Clean EVAP vapor line
EVAP system not working vapor canister purge valve blockage

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CITS : Automotive - Mechanic Diesel - Lesson 31 - 38 CITS : Automotive - Mechanic Diesel - Lesson 31 - 38