How Does a Carburetor Work?

[JohnnyFitz]

The working principle of a carburetor is as follows: 1. Air from the outside is filtered and then enters the carburetor, with the amount of air intake controlled by the position of the choke valve. 2. The air rushes through the venturi inside the carburetor, creating suction that draws fuel from the float chamber through the nozzle and atomizes it. 3. The atomized fuel mixes with air and is then drawn into the cylinder through the intake manifold. The amount of the air-fuel mixture is controlled by the throttle pedal, which operates the throttle inside the carburetor. 4. The amount of fuel pumped into the float chamber by the fuel pump is controlled by the float inside the float chamber. The float rises and falls with the fuel level in the float chamber. When the float chamber is filled with gasoline, the float rises and uses its needle valve to block the fuel inlet.

[AsherDella]

The working principle of a carburetor sounds quite interesting. It is mounted on the engine and is responsible for mixing air and gasoline before delivering the mixture into the cylinders for combustion. When the engine starts, air flows rapidly through a narrow section in the middle, called the Venturi tube, creating a low-pressure zone. This low pressure draws gasoline from the float chamber through the fuel nozzle, where the fine droplets of fuel mix with the air to form a spray. The float chamber contains a float that maintains a constant fuel level, preventing too much or too little fuel. The entire system operates on mechanical principles without the need for electronic components, which is why it was common in older cars. However, changes in temperature or altitude can destabilize the air-fuel mixture, leading to difficulties in starting the engine or higher fuel consumption. Simply put, it generates combustible gas by using airflow to draw fuel—a classic design, but with insufficient control precision, which is why modern cars now use fuel injection systems.

[DawsonLee]

Let me start from the era of carburetors in the 1960s and 1970s, when almost all cars used them. When the engine operates, the intake stroke creates a vacuum, drawing air through the carburetor's venturi. The venturi is designed with various components, such as the throttle valve to control the air volume and the needle valve to adjust the fuel injection rate. The mixed gas then enters the intake manifold and reaches the cylinders for ignition. The beauty of the carburetor lies in its simple and reliable structure, with low manufacturing costs, making it accessible even for farmers' vehicles. However, its drawback is the cumbersome manual adjustment of the air-fuel mixture, and it could stall due to climate changes or different terrains. After the 1980s, as emission regulations tightened, electronic fuel injection systems rose to prominence, gradually phasing out carburetors. Nowadays, they occasionally appear on retro cars, serving as a nostalgic piece of technological history.

[ElenaLee]

Carburetor issues are common in older vehicles. My experience is that clogged fuel injectors often cause engine shaking. In terms of working principle, high airflow velocity creates negative pressure, which draws in and atomizes gasoline. If the fuel line is dirty and the nozzle is blocked, it cannot spray fuel evenly; a stuck float can cause the fuel level to be too high, leading to fuel overflow into the engine. Mixture imbalance is also common—when the air-fuel ratio is unstable, the engine may lack power during acceleration or experience a surge in fuel consumption. During inspection, disassemble and clean the components, flush the injector pipes with specialized cleaner, and then adjust the screws. Regular use of high-quality gasoline to prevent carbon buildup can reduce malfunctions. Simply put, it mixes fuel by suction, and with proper maintenance, it remains durable.