12668390
HITACHI 12668390 High Pressure Fuel Pump GM Silverado Tahoe Sierra Yukon 5.3L 6.2L V8
12658480, 12672535, 12688607, 12697965Integrated Pulse-Width Modulated Spill Valve Solenoid-200 barVehicle & Engine Fitment
| Vehicle | Engine | Years |
|---|---|---|
| Chevrolet Silverado 1500 5.3L | GM 4.3L V6 & 5.3L / 6.2L EcoTec3 Gen V V8 (LV3 / L83 / L84 / L86 / L87) | 2014-2020 |
| GMC Sierra 1500 6.2L | GM 4.3L V6 & 5.3L / 6.2L EcoTec3 Gen V V8 (LV3 / L83 / L84 / L86 / L87) | 2014-2020 |
| Cadillac Escalade 6.2L | GM 4.3L V6 & 5.3L / 6.2L EcoTec3 Gen V V8 (LV3 / L83 / L84 / L86 / L87) | 2015-2020 |
Technical Specifications
| Specification | Value |
|---|---|
| Pump Generation | Hitachi Radial Plunger High-Pressure Mechanical Fuel Pump |
| Operating Rail PressureCore Spec | |
| Cam Drive Type | Exhaust Camshaft Tri-Lobe via Roller Lifter (GM 12659746) |
| Flow Regulation Control | Integrated Pulse-Width Modulated Spill Valve Solenoid |
| Pump Flange Mounting Torque | 12 N·m + 45° (Even two-stage torque) |
| High Pressure Pipe Flare Nut Torque | 30 N·m |
| Tightening Torque | 30 N·m |
| Hold Down Torque | 12 N·m |
| Primary OEM Reference | 12668390, 12658480, 12672535, 12688607 |
| Engine Emission Compliance | Euro 6 / LEV III / Tier 3 Bin 30 |
| Standard Industrial Warranty | 12 Months / Unlimited Mileage |
| 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
Tools needed: 10mm socket, swivel extension, and torque wrench for pump mounting bolts, 17mm line flare nut wrench for high-pressure steel fuel pipe, Torque wrench calibrated for 10-35 N·m range, Clean engine oil or assembly lube for roller lifter and O-ring seal, Heavy shop towels and eye protection for residual fuel containment
- Disconnect vehicle battery; remove fuel pump fuse and crank engine for 5 seconds to depressurize low-pressure fuel line.
- Wrap shop towels around fuel line connection and slowly crack open high-pressure line flare nut to relieve residual rail pressure.
- Disconnect electrical wiring harness from the fuel volume control spill valve solenoid.
- Disconnect low-pressure fuel supply line quick-connect coupler from the pump inlet fitting.
- Loosen the two pump flange bolts evenly in alternating half-turn increments to relieve camshaft spring tension squarely.
- Withdraw pump assembly from the cylinder head; extract roller lifter GM 12659746 and inspect roller surface for pitting, flat spots, or axial play.
- Clean the pump mounting recess; lubricate new pump O-ring seal and new roller lifter with fresh engine oil.
- Rotate crankshaft manually until the camshaft drive lobe is positioned at its base circle (lowest point of travel).
- Install lubricated roller lifter into bore; seat fuel pump squarely into position and install mounting bolts finger-tight.
- Torque mounting bolts evenly in progressive passes to 12 N·m, followed by a final 45-degree angle turn.
- Start high-pressure line flare nut by hand to guarantee proper thread engagement; torque flare nut to 30 N·m.
- Reconnect low-pressure feed line and spill valve electrical connector; prime fuel system by keying ignition on for 10 seconds prior to starting.
- Cam Base Circle Positioning: Always verify the camshaft drive lobe is on base circle prior to torquing mounting bolts to avoid cocking the pump body against spring tension.
- Oil Dilution Verification: Sniff the engine oil dipstick for raw gasoline odor; if fuel dilution is detected, perform a complete engine oil and filter change immediately.
Frequently Asked Questions
What are the primary symptoms when 12668390 fails?
Primary symptoms include extended cold engine cranking, severe hesitation under wide-open throttle, rough idle RPM fluctuation, and Diagnostic Trouble Codes P0087 (Fuel Rail/System Pressure Too Low), P0089 (Fuel Pressure Regulator Performance), or P0300 (Random/Multiple Cylinder Misfire).
What is the exact tightening torque for 12668390?
The holding flange mounting torque is 12 N·m + 45°, and the high-pressure fuel pipe union nut must be torqued to 30 N·m.
Can I reuse the seals when replacing 12668390?
No. All high-pressure fuel seals, including Viton O-rings and combustion chamber Teflon rings, are strictly single-use. Reusing compressed seals will cause pressurized fuel leaks or combustion blowby into the cylinder head.
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.