Chapter V - The fuel supply system

The fuel supply system has the role of supplying the fuel and air necessary for combustion in the case of internal combustion engines and of ensuring the evacuation of burnt gases from the cylinders. The fuel mixture (air + gasoline) is made outside. It begins in the carburetor and continues during intake and compression.

The fuels used are: gasoline (for engines with spark ignition) and diesel fuel (for engines with compression ignition).

In the case of gasoline injection engines, the formation of the fuel mixture is done in the intake manifold or inside the cylinder.

The fuel supply system of engines with spark ignition (MAS)

It is composed of:

- the fuel tank: serves for storing the fuel necessary for engine operation. The fuel is sucked by the gasoline pump and discharged into the carburetor. In the carburetor, the gasoline together with the air (sucked and cleaned in the air filter) forms the fuel mixture that enters the cylinders;

- the gasoline pump: serves for the forced delivery of fuel from the tank into the carburetor;

- the carburetor: is an assembly of parts inside which the fuel mixture of air and fuel is produced, in the dosage and quantity required by the operating regime of the engine with spark ignition. In the carburetor the fuel is sprayed and mixed with the air;

- the air filter: stops the dust in the atmosphere from entering the combustion chamber;

- the exhaust manifold: serves for evacuating the burnt gases from the cylinders.

The fuel supply system of engines with compression ignition (MAC)

It is composed of:

- the fuel tank: serves for storing the fuel necessary for engine operation;

- the feed pump: serves for supplying the injection equipment of the engine with compression ignition;

- the fuel filters: serve for the preliminary cleaning of the fuel from impurities and from water;

- the injection pump: has the role of sending the diesel fuel with high pressure through the high-pressure pipes to the injectors;

- the injectors: are components that ensure the fine spraying and uniform distribution of the fuel in the combustion chamber. In the construction of engines with compression ignition mechanical injectors are used, which can be: open or closed;

- the mechanical speed governor: is an automatic mechanism through which the injection pump is adjusted so that it responds to the operating requirements of the engine.