Which component primarily influences the proper functioning of a fuel injector?

The nozzle design is the primary component influencing the proper functioning of a fuel injector. This is because the nozzle shape and size determine how the fuel is atomized and delivered into the combustion chamber. Proper atomization is crucial for efficient combustion; the injector must break the fuel into small droplets that mix well with air for optimal ignition and burn characteristics. The nozzle design also affects the spray pattern and angle, which significantly impacts combustion efficiency, power output, and emissions.

While other factors such as combustion chamber size, fuel viscosity, and type of fuel can affect engine performance, they do not have the direct, primary influence on the injector's ability to deliver fuel effectively. For instance, while fuel viscosity can affect the flow through the injector, the nozzle design is specifically engineered to handle various viscosities to ensure proper operation across different conditions. Thus, the design of the nozzle stands out as the most critical element in ensuring that the fuel injector functions effectively within the engine.