PRINCIPLES OF CARBURETION

LEARNING OBJECTIVE: Describe the operating systems and principles of a simple carburetor and a computerized controlled carburetor. Identify the different carburetor accessories and their functions. Identify and describe possible carburetor troubles and quick system checks.

The principles of carburetion are presented so you may better understand the inner workings of a carburetor and how the other components of the fuel system function to provide a combustible mixture or air and fuel to the engine cylinders.

Air is composed of various gases, mostly nitrogen and oxygen (78 percent nitrogen and 21 percent oxygen by volume). These gases are, in turn, made up of tiny particles called molecules. All substances, whether solid, liquid, or gas, are made up of molecules. In solids, such as ice or iron, the particles are held closely together so that they seem to have no motion. In liquids, the molecules are not held together tightly, so they can move freely with respect to each other. In gases, there is still less tendency for the molecules to bond; therefore, the molecules can move quite freely. The molecules of gas are attracted to the earth by gravity or by their weight. It is the combined weight of the countless molecules in the air that make up atmospheric pressure.