Mitsubishi FG35/FG40 Forklift Service Manual Set – S-15G 2001–2002 (P/N 99739-74100)

Use the chassis publication for truck systems and the engine or fuel-system publication that matches the installed equipment. The GM G6 engine book covers a different engine configuration from the Mitsubishi-powered trucks identified in the chassis book.

Engine coverage: The chassis book requires separate 6G72 and S6S engine manuals; the LP supplement is intended for use with the corresponding 4G63, 4G64, or 6G72 engine manual. Those internal-engine publications are not included. The GM book’s fuel-system coverage applies to units built before 01/01/2004.

PDF Search, Bookmarks and File Contents

Search and diagram detail: The chassis/mast PDF has no searchable text. The GM and LPG PDFs support text searches through much of their written content, but some tables and illustrated material are not searchable. All three files have embedded bookmarks labeled with publication-section filenames. Small labels in the checked schematics are readable when enlarged.

The ZIP contains three printable PDFs totaling 683 pages. That total already includes 30 pages of original covers and front matter, 27 further blank pages, and one repeated page in the LPG supplement.

Chassis Overhaul, Engine Repair and LPG Diagnosis

The following selected coverage highlights summarize the main workshop areas rather than reproduce the complete contents. Further topics include battery maintenance and scheduled replacement of safety-related parts.

• Driveline repair: Power-train removal, dry- and wet-clutch service, manual transmission overhaul, powershift clutch repair, and torque-converter and control-valve work.

• Axles, brakes and steering: Hub and differential service, brake-cylinder and shoe repair, booster testing, steering-gear overhaul, and power-cylinder repair.

• Hydraulics and mast: Pump and valve service, lift- and tilt-cylinder overhaul, hydraulic testing, and dual-stage panoramic-mast disassembly and adjustment.

• GM G6 engine: Engine replacement and step-by-step procedures for cylinder-head, timing-drive, crankshaft, piston, connecting-rod, and cylinder-block repair.

• LP-gas hardware: Tank inspection requirements, VFF30 fuel-lock service, Model J converter/regulator overhaul, CA100 mixer repair, and mixture and leak checks.

• Electrical and fuel diagnosis: Chassis wiring schematics, GM ECU flash-code tables, S-15G troubleshooting trees, diagnostic-screen descriptions, and ECU connector information.

This material suits experienced forklift service technicians equipped for component overhaul, precision measurement, hydraulic testing, and fuel-system diagnosis.

Powershift Testing and Mast Adjustment

The transmission chapters distinguish manual, 1-speed powershift, and automatic 2-speed arrangements. Diagnostic work includes pressure measurements, clutch-valve testing, converter-stall checks, starting-acceleration testing, and inching-pedal adjustment.

Mast procedures extend beyond removal to lift-bracket separation, chain and roller inspection, cylinder-stroke equalization, wear-strip positioning, and shim adjustment. Exploded mast drawings identify the parts involved in setting the final clearances.

The cooling chapter also separates fan-belt service methods by muffler arrangement and access-hole configuration. Its serial-break table helps identify the applicable access method before disassembly.

GM Engine Rebuilding and Fuel Controls

Mechanical diagnosis covers compression, misfire, engine noise, valve-train faults, oil leakage, and lubrication problems. Rebuild procedures include valve-guide and seat work, timing-chain replacement, balance-shaft service, camshaft-bearing replacement, crankshaft and rear-seal work, cylinder boring and honing, and piston and connecting-rod inspection.

Bearing-clearance measurements and machining checks support decisions about component reuse or replacement. The book also covers post-overhaul setup and testing.

Separate sections address carburetor rebuilding, electrical throttle/governor control, distributor installation and timing, alternator service, and starter testing. The LP section adds on-truck converter pressure checks, regulator and lockoff service, CA100 mixer repair, exhaust-analyzer mixture adjustment, governor setting, and accelerator-cable adjustment.

S-15G Controls and Fault Tracing

The S-15G material connects ECU operation with the fuel control solenoid valve, mixer/throttle body, oxygen sensor, pedal sensor, engine-temperature input, three-way catalyst, and fault lamp. Version 1 and Version 2 ECU illustrations and separate pneumatic- and cushion-model layouts distinguish the hardware arrangements.

Operating explanations cover open- and closed-loop fueling, electronic throttle/governor control, protective shutdowns, and limp-home responses. Diagnostic screens display manifold pressure, pedal angle, oxygen activity, battery voltage, actual and selected speed, operating mode, actuator output, LP lockout, and fault-light status.

The troubleshooting trees relate these readings to no-start, stalling, rough-idle, and acceleration complaints. S-15G fault codes clear when the ignition is switched off, so an intermittent complaint may require observation while the fault is present.

The S-15G troubleshooting section specifies complete regulator or mixer replacement when defective; the earlier pre-CARB repair-kit procedures should not be applied indiscriminately to that equipment.

Schematics and Workshop Tools

Circuit references include the gasoline and diesel Electrical System Schematics, the 1-speed powershift Hydraulic System Schematic, GM ECU Input/Output Interfaces and ECU Schematic, and the CARB 1 Tier 1 LP Fuel Vacuum System Diagram. The LPG wiring schematic is accompanied by ECU pin-location and function information.

Referenced equipment includes pressure-gauge kit 64309-17701, camshaft-bearing kit J 33049, torque-angle meter J 36660, GM ECU tester 91868-02300, and S-15G diagnostic units 93060-06300 and 93060-06400.

Component Damage and Service Precautions

The VFF30 instructions warn that excessive mounting-bolt length can damage the lockoff and that carburetor cleaner attacks its synthetic rubber seals. The converter instructions identify casting deterioration from steel fittings in its coolant passages.

GM rebuilding requires matched lifters, bearings, pistons, rods, and related parts to retain their original positions. Other cautions address torque-converter destruction during prolonged stall testing and ECU or EST-module damage from incorrect use of the powered timing shunt.

LP-gas service requires fuel isolation, safe depressurization, and ventilation. Hydraulic work requires pressure relief and secure support for the mast, forks, and other raised assemblies.

Compression and Pedal-Calibration Examples

For the GM G6, the room-temperature compression test specifies at least 689 kPa (100 psi) per cylinder, with the lowest reading at least 70% of the highest. The stated test conditions include a fully open throttle and a battery at or near full charge.

For S-15G pedal calibration, the adjustment target is 35 ± 5 diagnostic-display units with the pedal released and 195 ± 5 units at full pedal travel. These are display units, not degrees of pedal angle.