What are the main parts inside a Cummins PT injector? A typical Cummins PT injector includes several critical parts: the barrel and plunger (which meter and pressurize fuel), the metering valve (controls fuel quantity), the check ball and seat (provides a seal), the injector spring (returns the plunger), and the nozzle tip (sprays fuel into the cylinder). Other components include shims for adjustment, O-rings for sealing, and a retaining nut that holds everything together. Each part must work precisely with the others. https://www.cq-longshine.com/cummins-injector-parts