Mitsubishi 4G63/4G64 Forklift Engine Service & LPG Manual Set

Use the engine manual for mechanical repair and the supplement for LP-gas fuel-system service. The supplement is designed for use with the corresponding engine service manual.

Engine-out service: The engine manual describes service with the engine removed from the truck. Engine removal, on-truck inspection, and model-specific vehicle service are referred to separate truck service manuals. For 6G72 work, the supplement requires the separate 6G72 engine manual.

Search, Bookmarks, and the Two-PDF Package

Text search and diagram detail: The engine manual has no searchable text. The LP-gas supplement has searchable body text, although some illustration content remains image-based. Both PDFs have embedded bookmarks labeled with document codes. Small electrical-diagram labels are readable with enlargement in the checked pages.

The ZIP download contains two printable PDFs totaling 190 pages. The page counts include both covers, introductory and contents pages, five blank pages, and one repeated page in the LP-gas supplement.

Engine Overhaul and LPG Fuel-System Diagnosis

This selected content overview highlights the main repair areas rather than reproducing the complete contents. Other topics include LP-gas fuel selection and its effects on vaporizer contamination.

• Timing and valvetrain: Step-by-step timing-belt removal, installation, and tensioning; rocker-arm and camshaft service; cylinder-head, valve-guide, valve-seat, and valve-stem seal procedures.

• Bottom-end repair: Piston-pin service, connecting-rod and crankshaft inspection, bearing selection, cylinder boring, and front-case, oil-pump, and oil-pan procedures.

• Gasoline fuel and cooling: Carburetor disassembly, float-level and choke checks, fuel-pump replacement, air-governor service, intake/exhaust manifold work, and water-pump removal and installation.

• Starting, charging, and ignition: Alternator and starter overhaul, ignition-coil tests, distributor inspection, spark-plug cable installation, and symptom-based electrical troubleshooting.

• LP-gas equipment: Pre-CARB mixer, converter/regulator, and VFF30 fuel-lock disassembly and reassembly, with pressure checks, idle and power-mixture adjustments, and gas-leak checks.

• S-15G electronic diagnosis: Diagnostic-device setup, pedal-sensor adjustment, live-data interpretation, blink-code tables, vacuum diagrams, wiring schematics, and ECU pin identification.

The overhaul procedures and S-15G diagnostic requirements suit experienced engine technicians with measuring equipment, specified service tools, and access to the required diagnostic device.

Rebuild Details and Service References

Bearing and block selection: From serial 4C1709 and up, the cylinder-block change involves a new-style crankshaft, different center No. 3 main-bearing choices, and a new thrust-bearing set. The former block can be replaced by the revised block only with the associated new components. That distinction matters when selecting internal engine parts during a rebuild.

Lash-adjuster coverage includes air bleeding and leak-down testing. The piston and crankshaft sections explain plastic-gauge clearance checks, bearing identification, and oversize cylinder work.

Tools and specifications: Named tools include the MD998727 Oil Pan Remover, MD998440 Lash Adjuster Leak-Down Tester, MD998772 Valve Spring Compressor, MD998778 Crankshaft Sprocket Puller, and MD998780 Piston Pin Setting Tool.

Reference tables cover compression pressure, ignition timing, wear limits, clearances, fluid capacities, conventional dry torque, and torque-plus-angle fasteners. Timing-belt inspection, adjustment, and replacement intervals are also specified.

Excess FIPG can squeeze into and restrict an engine fluid-feed passage. The air-governor section also restricts disassembly of the factory-sealed assembly to authorized service circumstances.

Pre-CARB LPG Service and S-15G Limits

The supplement explains the tank, pressure-relief valve, fixed liquid-level gauge, service valve, vacuum fuel-lock filter, hydrostatic relief valve, and converter/vaporizer. The pre-CARB chapters provide component overhaul procedures and converter pressure testing.

Different repair approaches: The S-15G troubleshooting section calls for complete replacement of a defective regulator or mixer assembly and states that repair kits are unavailable for those assemblies. The pre-CARB rebuild procedures should therefore not be treated as S-15G overhaul instructions.

On the VFF30 fuel lock, overly long mounting bolts can severely damage the lockoff, while carburetor cleaner can erode its synthetic-rubber seals.

LP-gas tank, valve, and level-indicator work involves high-pressure components; the supplement directs that disassembly to legally qualified personnel and certified shops.

S-15G Controls, Fault Tracing, and Schematics

The CARB Tier 1 material describes ECU versions 1 and 2, the oxygen sensor, pedal sensor, engine-block temperature sensor, fuel-control solenoid valve, electronic throttle body, and three-way catalytic converter. Operating explanations cover warm-up, closed-loop fuel control, governed speed, overspeed shutdown, and over-temperature limp-home behavior.

Diagnostic equipment: The manual specifies laptop diagnostic kit 93060-06300 or handheld diagnostic unit 93060-06400. Live data includes pedal angle, MAP, engine temperature, oxygen-sensor voltage, battery voltage, FCSV dwell, and operating mode.

Blink-code tables identify fuel-system, pedal-sensor, engine-temperature, battery-voltage, and TACH/RPM faults. The ECU does not retain fault codes after restart, an important detail when investigating intermittent symptoms. The throttle-sensor section also warns that excessive accelerator force with the floor plate removed can damage the potentiometer.

Illustrations include the 4G63 Side Cutaway View, LP-gas Device Layout, Mixer and Throttle Body Internal Gas Flow, CARB Tier 1 Vacuum System Diagram, S-15G Fuel System Wiring Schematic, and ECU Pin Location and Function. Together, the live-data explanations, fault tables, and circuit references support tracing a symptom to the relevant sensor, wiring, or fuel-control component.

A Preview of Capacity, Torque, and Sensor Data

For the covered 4G63/4G64 engines, the specification table lists an engine-oil capacity of 4.8 L including the filter and a coolant capacity of 3.1 L in the engine proper.

The timing-belt torque table specifies 118 N·m for the crankshaft bolt. For S-15G diagnosis, the screen-layout reference lists a normal oxygen-sensor voltage range of 0.10–0.85 V alongside the other monitored operating parameters.