User Manual

The HEUI injector consists of three major parts:
• Upper end, or actuator (A)
• Middle, or pumping unit (B)
• Lower end, or nozzle assembly (C)
The upper end (A) consists of the following items:
• Solenoid (1)
• Armature spring (2)
• Armature (3)
• Seated pin (4)
• Spool spring (5)
• Spool valve (6)
• Check ball for intensifier piston (7)
The middle of the injector (B) contains the following items:
• Intensifier piston (8)
• Return spring (9)
• Plunger (10)
• Barrel (11)
The lower end of the injector (C) consists of the following items:
• Nozzle case (12)
• Inlet fill check (13)
• Stop (14)
• Nozzle spring (15)
• Check piston (16)
• Sleeve (17)
• Reverse flow check valve (18)
• Nozzle check (19)
• Nozzle tip (20)
These components work together in order to produce different rates for fuel injection. The rates for fuel
injection are electronically controlled by performance software in the ECM.
HEUI Fuel Injector (Operation)
The HEUI injector operates with a split injection cycle. The split injection cycle has five phases of injection:
• Pre-injection
• Pilot injection
• Injection delay
• Main injection
• Fill