What consists in fuel supply system in diesel engine?

Fuel supply system of diesel engine consists of the following components:

* Fuel tank
* Fuel lift pump or fuel feed pump
* Fuel filter
* Fuel injection pump
* High-pressure pipe
* Overflow valve
* Fuel injector

Fuel is drawn from the fuel tank by the fuel feed pump and forced to the injection pump through the fuel filter. The injection pump supplies high-pressure fuel to injection nozzles through delivery valves and high-pressure pipes. Fuel is injected into the combustion chamber through injection nozzles. The fuel that leaks out from the injection nozzles passes out through the leakage pipe and returns to the fuel tank through the overflow pipe.

The overflow valve installed at the top of the filter keeps the feed pressure under a specified limit. If the feed pressure exceeds the specified limit, the overflow valve opens, and then the excess fuel returns to the fuel tank through the overflow pipe.

Fuel tank

It is a storage tank for diesel. A wire gauge strainer is provided under the cap to prevent foreign particles from entering the tank

Fuel lift pump

It transfers fuel from the fuel tank to the inlet gallery of the fuel injection pump

Preliminary filter (sediment bowl assembly)

This filter is mostly fitted on a fuel lift pump. It prevents foreign materials from reaching inside the fuel line. It consists of a glass cup with a gasket.

Fuel filter

Mostly two-stage filters are used in diesel engines
1. Primary filter 2. Secondary filter
The primary filter removes coarse materials, water, and dust. A secondary filter removes fine dust particles.

Fuel injection pump

It is a high-pressure pump that supplies fuel to the injectors according to the firing order of the engine. It is used to create pressure varying from 120 kg/cm2 to 300 kg/cm2. It supplies the required quantity of fuel to each cylinder at the appropriate time.

Air venting of fuel system

When the air has entered the fuel lines or suction chamber of the injection pump, venting should be done properly.. Air is removed by the priming pump through the bleeding holes of the injection pump.

Fuel injector

It is the component that delivers finely atomized fuel under high pressure to the combustion chamber of the engine. Modern tractor engines use fuel injectors that have multiple holes. The main parts of injectors are the nozzle body, and needle valve. The needle valve is pressed against a conical seat in the nozzle body by a spring. The injection pressure is adjusted by adjusting a screw. In operation, fuel from the injection pump enters the nozzle body through the high-pressure pipe. When fuel pressure becomes so high that it exceeds the set spring pressure, the needle valve lifts off its seat. The fuel is forced out of the nozzle spray holes into the combustion chamber.

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