12668649
HITACHI 12668649 Direct Fuel Injector GM Silverado Sierra Tahoe Yukon 5.3L 6.2L V8 EcoTec3 L83 L86 FJ1217
12623116, 12656932, 12668390, FJ1217, 842-12384, 12698484--150 barTechnical Specifications
| Specification | Value |
|---|---|
| part_number | 12668649 |
| oem_reference | 12668649 |
| manufacturer | HITACHI |
| system_type | Fuel Injector |
| pressure_rating | 150 bar (2175 psi) |
| operating_temperature | -40°C to +135°C |
| flange_mount_torque | 12 N-m (106 lb-in) |
| high_pressure_line_torque | 28 N-m (21 lb-ft) |
| diagnostic_dtc | P0300, P0301, P0171, P0172 |
| Operating PressureCore Spec |
Matched High-Pressure Fuel Pump (Fuel Circuit Assembly)
Operates on the same high-pressure rail circuit. When troubleshooting low rail pressure (DTC P0087), verify pump volumetric delivery before replacing injectors.
Installation Tips
- Depressurize the fuel system completely via diagnostic scan tool or by removing the fuel pump fuse prior to line disassembly.
- Clean all surrounding bracket areas thoroughly using residue-free brake cleaner to prevent abrasive particulate ingress.
- Inspect the mechanical camshaft lobe and roller follower or clean injector bore seating surfaces before hardware alignment.
- Install component using fresh factory O-rings or Teflon combustion chamber seals lubricated only with clean motor oil.
- Torque mounting flange fasteners in alternating increments to 12 N-m (106 lb-in).
- Torque high-pressure hydraulic tube fittings using a calibrated flare nut wrench to 28 N-m (21 lb-ft).
- Prime low-pressure fuel circuit, cycle ignition key 3-4 times, and inspect for high-pressure hydraulic leaks before road test.
- Always replace single-use high-pressure metal fuel lines and micro-filter seals whenever disconnected.
- Verify camshaft driving lobe surfaces for scoring or flat spots before installing any mechanical pump.
- Reset long-term and short-term fuel trim adaptations via OBD-II diagnostic scanner after physical replacement.
Diagnostic Trouble Codes & Fault Protocols
Common diagnostic trouble codes (DTCs) triggered when this common rail injector experiences wear, circuit faults, or calibration drift:
Fuel Rail / System Pressure Too Low
Excessive internal backleak from worn control valve seats drops common rail pressure below target under engine load.
Injector Circuit Malfunction / Open Circuit
Solenoid coil resistance drift (0.2-0.5 Ω) or piezo stack degradation triggers driver stage shutdown on affected cylinders.
Cylinder Misfire & Balancing Deviation
Carbon-clogged nozzle spray holes or missing IMA calibration causes uneven cylinder contribution. Recode ECM and verify washer seating.
Fuel Rail / System Pressure Too High
Spill line backpressure or stuck metering valve prevents rail depressurization, creating overpressure risks under load.
Technical Diagnostic & Service Protocols
Authoritative field procedures, diagnostic testing thresholds, and service SOPs for this assembly.