Saturday, 3 November 2018


How does an injection system work?
For the engine to run smoothly and efficiently, it must be equipped with the right amount of fuel / air mixture according to its diverse requirements.

Fuel injection system

Gasoline cars use indirect fuel injection. The fuel pump sends the gasoline to the engine position and injects it into the intake manifold. There is either a single injector for each cylinder or one or two injection nozzles in the suction line.
Traditionally, the fuel and air mixture is
controlled by a carburetor, a tool that is by no means perfect.
Its main disadvantage is that the only carburetor that delivers the four-cylinder engine cannot give each cylinder exactly the same fuel / air mixture as some cylinders are far from the carburetor than others.
One solution is to couple two carburetors, but it is difficult to tune it properly. Instead, many cars are now fitted with fuel injection engines, where the fuel is delivered in precise flashes. Engines that are so equipped are usually more efficient and powerful than those that are carburetor and can also be more economical and have less poisonous emissions.

Diesel fuel injection

The fuel injection system in gasoline cars is always indirect, gasoline is injected into the intake manifold or intake duct, and not directly into the combustion chambers. This ensures that the fuel mixes well with the air before it enters the chamber.
However, many diesel engines use direct injection, in which the diesel is injected directly into a cylinder filled with compressed air. Others use indirect injection, in which diesel fuel is injected into a special pre-combustion chamber, which has a narrow passage connecting it to the cylinder head.
Only air is drawn into the cylinder. It is heated to such a degree of compression that the atomized fuel injected at the end of the compression stroke self-ignites.

Primary injection

All modern gasoline injection systems use indirect fuel injection. A special pump delivers pressurized fuel from the fuel tank to the engine compartment, where, under pressure, it is distributed individually over each cylinder.
Depending on the particular system, the fuel is injected either into the intake manifold or into the inlet through the injector. It works just like a spray nozzle hose, ensuring that the fuel comes out in the form of a shallow mist. The fuel is mixed with air passing through the intake manifold or port, and the fuel-air mixture enters the combustion chamber.
Some cars have multipoint fuel injection, where each cylinder is powered by its own injector. It is difficult and can be expensive. Single-point injection is most commonly used when one cylinder feeds all cylinders, or one injector for every two cylinders.


The injectors through which fuel is sprayed are screwed in first into the injectors either in the intake manifold or in the cylinder head and angled so that the fuel is sprayed in the direction of the intake valve.
Injectors of one of two types, depending on the injection system. The first system uses continuous injection, when fuel is injected into the intake channel all the time while the engine is running. The injector simply acts as a spray nozzle, breaking the fuel into small sprays — it doesn’t actually control the flow of fuel. The amount of fuel sprayed is increased or decreased using a mechanical or electrical control unit — in other words, it's like turning the faucet on and off.
Another popular system is synchronized injection (pulse injection), when fuel is supplied in batches that coincide with the cylinder intake stroke. As in the case of continuous injection, the programmed injection can also be controlled either mechanically or electronically.
The earliest systems were mechanically controlled. They are often referred to as petrol injection, and the fuel flow is controlled by a mechanical regulator assembly. These systems suffer from the drawbacks of mechanical complexity and a bad reaction to gas shutoff.

There are two types:

Mechanical Injection system
Electronic Injection system

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