What is mechanically or electronically connected to the carburetor or EFI computer to control fuel flow?

The throttle is the component that is mechanically or electronically connected to the carburetor or the electronic fuel injection (EFI) computer to control fuel flow. When the driver presses down on the accelerator pedal, the throttle opens, allowing more air to enter the intake manifold. This increase in air intake signals the carburetor or EFI system to deliver more fuel to the engine to maintain the correct air-fuel ratio for combustion.

The throttle's position directly influences fuel flow, as the computer or carburetor adjusts the amount of fuel injected based on how open the throttle is, thus optimizing engine performance. This connection is critical for the vehicle's performance, as it helps maintain efficiency and responsiveness based on driving conditions.

In contrast, the other components listed do not control fuel flow. The radiator is responsible for cooling the engine, the water pump circulates coolant, and the fuel injector is part of the EFI system that delivers fuel to the engine but is not the component that controls fuel flow itself; that function lies with the throttle in relation to the carburetor or EFI computer.