Unlike common rail systems where a high-pressure pump supplies fuel directly to the injectors, the PT system has a more mechanical and elegant approach. The process involves two main functions:

• Metering (The "P" - Pressure): Fuel from the PT pump enters the injector at a controlled, variable pressure. This pressure, along with a precisely timed "fill" period when the injector cup is open, determines the amount of fuel metered into the injector cup. More pressure from the pump means more fuel is metered for the injection cycle.

• Injection (The "T" - Time): The "Time" refers to the very short window for the injector to receive fuel. The actual injection event is powered mechanically by the engine's camshaft. A pushrod and rocker arm force the injector plunger down, which instantly pressurizes the metered fuel in the cup to over 20,000 PSI and forces it through the injector tip into the cylinder.

In short: The PT Pump controls fuel quantity by supplying fuel at a specific pressure, and the Injector, actuated by the camshaft, controls fuel timing and creates the injection pressure.

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