Carburetors and Electronic Fuel Injectors (complete search)

first :Carburetors

The carburetor is the part of an automobile engine that converts liquid fuel into vapor. This is mixed with a certain amount of air that allows combustion in the cylinders. All gasoline vehicles have carburetors, including boats and light aircraft. Carburetors are generally found in small engines and in older automobiles, especially those used in stock car racing. Most engines have only one carburetor though most modern engines that have bigger engines or more than 4 cylinders use multiple carburetors.
The history of carburetors can be traced to the development of the wick carburetor by Donat Banki, a Hungarian engineer in 1893. Frederick and his brother built the first petrol driven car in 1896. Then in 1900, they built a 2-cylinder engine using the new wick carburetor. This car was taken on a successful 1000-mile tour, marking an important landmark in the use of the carburetor in automobiles.

There Are Two Types Of Carburetors

There are two types of carburetors: fixed choke and constant depression, the first type, fixed choke carburetors, makes the varying air pressure in the venture alter the fuel flow; this is the common downdraft carburetor found on American and most Japanese cars. The other type, the constant depression carburetors vary the airflow to change the fuel jet opening witch in turn altars the fuel flow. A vacuumed operated piston connected to a tapered needle, which slides inside the fuel jet, does this. The most common variable choke (constant depression) type carburetor is the side draft SU carburetor, which was simple in principle to adjust and maintain. This rose to a position of domination in the UK car market for that reason. Other similar designs are used on some European and a few Japanese automobiles.
Although the differences between the two types of carburetors are extensive there main function remains, they need to measure the airflow of the engine at any time, and then deliver the correct amount of fuel to keep the fuel/air mixture perfect and then mix the fuel and air evenly. A carburetor must provide the proper fuel/air mixture under a wide variety of different circumstances and engine speed range, random events that will affect the performance of the carburetor can be things like acceleration and cold start, waiting at a red light etc. This will be hard to do when you on top of this will need to maintain as low rates of exhaust emissions as humanly possibly for a poor carburetor.
To function correctly under all these conditions, most carburetors contain a complex set of mechanisms to support several different operating modes, called circuits.

--> An other difference between a carburetor and an injection is the way it is utilized when cold starting an engine, when the engine is cold, fuel vaporizes less readily and tends to condense on the walls of the intake manifold, starving the cylinders of fuel and making the engine difficult to start; thus, a richer mixture (more fuel to air) is required to start and run the engine until it warms up. In an injection engine a computer will control this automatically, but again the carburetor has to do this manually, therefore you will see a choke on a carbureted car and usually not in an injection based car.

The main parts in a carburetor are an open pipe, which is the carburetor's "barrel" or "throat" through which the air reaches the engine. The butterfly valve or the "throttle", a rotating disc in this pipe, controls the air flow through the carburetor throat, which influences the power and speed of the engine. This throttle is connected to the accelerator of the vehicle. The major manufacturers of carburetors are Amal Ltd., Autolite, Carter, Holley, Pierburg, Rochester, Solex, Stromberg, SU, Walbro and Tillotson (small engines), Briggs and Stratton, Villiers, Weber, and Zenith

second: Electronic Fuel Injectors

Today's modern cars have electronic fuel injection systems, earlier automobiles used carburetors that are less efficient and did not perform to the best. However, even, today many kinds of cars come with small engines that use carburetors. Both the carburetor and the electronic fuel injection system are kinds of engineering equipment that supply fuel to the engine.
Initially, throttle body fuel injection systems, or single point systems were introduced in the market. In this equipment usually electricity used to control fuel injector valve. Later, single point systems were replaced by better and powerful multi-port fuel injection systems that use a separate fuel injector for each cylinder. Multi-port fuel injectors provide accurate amount of fuel to each cylinder and increases the efficiency to the next level.

Fuel Injector & Plug


Fuel Injection System- An Introduction:

As most of us are aware of that the Carburetor is meant for fuel supply to the engine and it worked well also since long with petrol internal combustion engines (for both 2-stroke and 4-stroke engines) but the stricter emission norms all over the World put more pressure on the efficiency of the engines which directly affects the working of Carburetors. The evolution of Catalytic Converters put further pound on the Carburetor technology as the Catalytic Converters trap the excess residual Oxygen molecules emitted from the combustion chamber resulting early clogging of the catalytic converter. The emission of the excess residual Oxygen molecules was needed to be checked badly and unfortunately the technology of the Carburetor was inefficient to regulate the Oxygen content from both the intake air and the residual gases. To curb this need of relatively cleaner emission from the internal combustion engines Fuel Injection System was developed.

Fuel Injection System- Working:

The Fuel Injection System as the name suggests is mainly consists of an Injector or a valve with a small nozzle at the extreme end which is responsible to supply the fuel to the combustion chamber with force resulting the Atomization of the fuel (breaking of the fuel particles into much smaller molecules), this force is generated from the fuel pump which is generally placed inside the fuel tank, the atomized fuel is easier to burn when combined with the radical oxygen molecules of the air intake creating an optimum fuel and air ratio hence resulting into increased fuel efficiency with remarkably cleaner emission.

Internal Combustion Process

The early model of Fuel Injection System became more efficient when it becomes Electronic Fuel Injection System (EFI). The EFI System is consists of following parts:

Engine Control Unit (ECU):

The ECU is a small but very efficient computer chip responsible to calculate and monitor the activities of the engine through various sensors planted at different parts of the bike. On the basis of the information collected from the sensors the ECU controls the Fuel Injector’s timing to release the fuel it also governs the duration of the fuel released which in turn affects the volume of fuel injected in the combustion chamber.

Engine Sensors:

There are sensors placed at different parts of the bike attached to the ECU and from where these sensors continuously send the data to the ECU to calculate and monitor the fuel supply through the Injector.
  • Mass Airflow Sensor (MAS) – Also called as MAP sensor, it is responsible to send the data pertaining to the mass of the air entering into the combustion chamber.
  • Oxygen Sensors- These sensors are attached to the Catalytic Converter and responsible to monitor the volume of Oxygen in the exhaust, on the basis of the data sent, the ECU decides how rich or lean fuel and air mixture should be.
  • Throttle Position Sensor – TPS monitors the position of the Throttle Valve, which is directly governed by the accelerator cable and determines how much air goes into the combustion chamber. On the basis of the data given by the TPS, the ECU decides how much fuel is required to be injected.


The Fuel Injector is simply electronically regulated valve, which can squirt the pressurized fuel through small nozzle present at the extreme end. When the injector is charged an electromagnet moves the plunger to allow the pressurized fuel to come out from the nozzle in atomized form, the atomized tiny particles of the fuel burns easily when mixed with oxygen molecules.

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