Which of the following components is NOT part of the piston assembly?

The fuel injector is not part of the piston assembly. The piston assembly primarily includes components that are directly involved in the motion and function of the piston itself within an engine. This typically consists of the piston, which moves back and forth in the cylinder to create the necessary pressure for combustion; the wrist pin, which connects the piston to the connecting rod and allows for rotational movement; and the connecting rod, which transmits the motion from the piston to the crankshaft.

In contrast, the fuel injector is part of the fuel delivery system and is responsible for introducing fuel into the combustion chamber. While it plays a crucial role in the overall operation of an internal combustion engine, it does not have a direct relationship or function within the piston assembly. Understanding the specific roles of each component helps clarify why the fuel injector is excluded from the list of parts that make up the piston assembly.