TL960 SERVICE MANUAL
High pressure oil flows around poppet to the top of intensifier piston.
Pressure on the top of the intensifier forces it down along with the plunger. The downward movement of the plunger pressurizes the fuel in the plunger cavity and nozzle. When the fuel pressure reaches Valve Opening Pressure (VOP) of about 4,500 psi, the nozzle valve lifts off its seat and injection begins.
As long as the solenoid is energized, the poppet remains open and pressurized oil continues to flow in, pushing down the intensifier and plunger. Injection pressure ranges from 5,000-21,000 psi depending on engine requirements. Injection continues until the solenoid is deenergized, allowing the poppet spring to close the poppet and shut off the high pressure oil.