Page 316 - Mechanic Diesel - TT

MECHANIC DIESEL - CITS

MODULE 15 : Diesel Fuel System

LESSON 94 & 95 : Importance of testing the pumps

Objectives

At the end of this lesson you shall be able to
• explain importance of testing the pumps.

• To check whether the pressure from the fuel pump is generally from 0.176to 0.264 kg/cm.
• To check if vacuum is created in fuel pump.

• To test the capacity of the fuel pump.
• For checking pump phasing or delivery.
• To check if the control rod and gear in the pump are worn.
• To check if there is leakage in high pressure pipeline.

• If the low pressure pipe is obstructed.
• If the pump injection timing is wrong.
• If the pump makes noise.
• If the opening pressure of the injector is higher.
• In case of high consumption of diesel.

• If excessive fuel is burned at idling speed.

Procedure for testing before dismantling pump

Objectives : At the end of this lesson you shall be able to
• state about the procedure for testing before dismantling pump

Introduction
Inside the diesel engine, pure air is taken through the inlet valve and compressed in the cylinder. Due to higher
compression ratio in the compression stroke, its temperature and pressure increases and when the piston is
about to reach the compression stroke, diesel is sprayed into the combustion chamber by the injector.
That spray is in atomization form. By injecting diesel, compressed air and automated diesel are ignited, providing
the power stroke to the engine. Diesel engine is also called ‘compression ignition’ engine. It is very important
to spray diesel at the right time. Diesel is one of the heavier oils and it must have the properties of flowing
smoothly and burning quickly in the pipelines of the fuel system. Burning of diesel is based on cetane number,
the diesel which has higher cetane number burns more quickly and the diesel which has lower cetane number
will require more compression heat to burn. Low speed and high speed diesel engines are made on the basis of
this principle....
Testing a fuel pump typically involves checking its pressure output and flow rate to ensure it’s functioning properly.
You’ll need a fuel pressure gauge and possibly a flow meter, along with a vehicle-specific manual for the correct
pressure specifications.

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