Carburetor: Carburetion is the process of measuring, mixing and supplying to a spark ignition engine continuously a suitable combustible mixture of fuel and air. This mixture supply must be in accordance with the engine speed and load requirements. The carburetor supplies this mixture to an engine. The carburetor consists basically of a float chamber and a metering cum mixing chamber.
Fuel feed system of carburetor engines
The preparation of air fuel mixture and its supply to the cylinders of the carburetor engine, the adjustment of its quality and quantity are accomplished by the fuel feed system. The feed system operation has a large effect on all the principal engine parameters. Therefore, necessary care must be taken to keep this system in proper working order during the engine use.
The system has a storage tank with fuel level amount sensing element, fuel gauge, filter, pump for supplying fuel from tank to carburetor. The fuel tank cap is vented. The atmospheric air enters the carburetor via air filter which acts at the same time as an intake silencer. From the carburetor, the fuel air mixture is supplied to the cylinder via intake duct.
An electric gauge with balanced coils is used in many cars for indicating the quantity of fuel available in the fuel tank. The gauge is mounted on the instrument panel in front of the driver. This type of electric fuel gauge consists of two units a dash unit and a tank unit.
Some of the fuel tanks include a fuel filter at their exit or a sump at the bottom, to collect dirt and water and prevent them from reaching the pump and carburetor. Some tank are provided with a drain plug on the bottom for emptying the tank. Fuel tanks are often provided with vertical baffles to prevent surging of the fuel.
An additional fuel strainer is usually placed in the fuel line either before the pump as shown in the picture or after pump to filter gasoline before it enters the float chamber. The unit serves to catch any water or foreign particles that were not filtered out previously, in the fuel tank filter unit. One type of filter is shown in the picture. The fuel that enters into the glass bowl, passes through a ceramic filter to reach the inside section that is connected with the exit. The water and sediment are collected in the bowl which is made removable for cleaning.
Some engines use a disposable fuel filter in the fuel feed system. The entire unit may be replaced whenever it becomes inoperative, simply by loosening snap clamps.