The Cummins PT Fuel Injector is a key component of the PT (Pressure-Time) fuel system, a unique and ingenious design developed by Cummins Engine Company. Unlike common rail or unit injector systems that use high-pressure pumps to both meter and inject fuel, the PT system separates these functions.
The "PT" stands for Pressure-Time, which describes the fundamental principle of how the fuel is metered:
Pressure: The fuel pressure, regulated by the PT fuel pump (gear pump), determines how fast the fuel flows to the injector.
Time: The duration (time) that the injector is open to receive that fuel determines how much fuel enters the combustion chamber. The injector opening is controlled mechanically by the engine's camshaft.