12698484
HITACHI 12698484 High Pressure Fuel Pump GM Buick Envision Cadillac CT4 CT5 XT4 2.0T LSY 350 bar
12683985, 12694539, 12708365, HFS034-135Integrated Pulse-Width Modulated Electric Spill Valve (SCV)-350 barTechnical Specifications
| Specification | Value |
|---|---|
| Manufacturer | Hitachi Astemo / General Motors Genuine Parts |
| System Technology | 350 bar (35 MPa / 5076 psi) Ultra-High Pressure SIDI Mechanical Pump |
| Drive Cam Element | Camshaft Follower Roller Lifter (GM 12674744) on Exhaust Cam |
| Mounting Flange Fastener Torque | 12 N·m + 45° Torque-To-Yield (TTY) M6 Bolts |
| High Pressure Pipe Joint Torque | 32 N·m Flare Nut Connection |
| Control ValveCore Spec | |
| Diagnostic Fault Codes | P0087 (Fuel Rail Pressure Low), P0089 (Fuel Pressure Regulator Performance), P016F |
| Common Symptoms | High-pressure fuel odor in oil filler cap, rising crankcase oil level, check engine light & hesitations under load |
| 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
- [
- {
- "step": 1,
- "title": "Relieve 350 bar High-Pressure Fuel Rail",
- "instruction": "Disconnect fuel pump control module (FPCM) harness. Crank engine for 10 seconds. Check GDS2 scan tool to verify fuel rail pressure is below 1 MPa."
- },
- {
- "step": 2,
- "title": "Inspect Engine Oil for Gasoline Dilution",
- "instruction": "Check dipstick and oil filler cap. If oil smells strongly of gasoline or viscosity has degraded due to pump shaft seal leakage, replace engine oil and filter."
- },
- {
- "step": 3,
- "title": "Inspect Roller Lifter Tappet GM 12674744",
- "instruction": "Slide out roller lifter from cylinder head. Inspect roller bearing for pitting or flat spots. Coat lifter in clean engine oil prior to reinsertion."
- },
- {
- "step": 4,
- "title": "Torque Pump Flange Bolts to TTY Spec",
- "instruction": "Set camshaft drive lobe to low circle. Hand-start new TTY flange bolts. Tighten evenly in alternating stages to 12 N\u00b7m, then apply a final 45-degree angle turn."
- },
- {
- "step": 5,
- "title": "Connect High-Pressure Hard Line & Torque",
- "instruction": "Align high-pressure delivery pipe into pump outlet. Hand-tighten flare nut squarely, then torque flare fitting to exactly 32 N\u00b7m."
- }
- ]
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.