A fuel injector is provided. The fuel injector is operable to inject fuel at extremely high pressures which creates very small droplet sizes, allowing for efficient self-ignition of the fuel and allows for clean, efficient combustion due to the small droplet sizes. The fuel injector uses pressure from within a combustion chamber to actuate the spraying of fuel from the injector, thereby solving many problems experienced by typical fuel injectors and eliminating many problem-components of prior art fuel injectors.