1991–2000 Tohatsu Marine Engine 2hp to 140hp Service & Repair Manual (P/N B790)

• Covers carbureted two-stroke Tohatsu outboards from 2.5 through 140 hp, including manual-start and electric-start, tiller and remote controls, multi-cylinder engines, and model-specific A/B/C/D/D2/E/E2 configurations.
• Details flywheel and powerhead removal, cylinder-block disassembly and reassembly, cylinder-head and exhaust-cover service, piston/rod/crankshaft inspection, and break-in after internal repair.
• Follows gearcase removal and teardown, water-pump overhaul, propeller-shaft and bearing work, pinion-height setting, shim selection, and forward- and reverse-gear backlash checks.
• Includes starting, CDI ignition, charging, warning/RPM-limiter, cooling, fuel, and trim/tilt fault isolation, plus carburetor synchronization, oil-pump alignment, ignition timing, throttle-linkage, and trim-sender adjustments.
• Supplies a 40-page wiring-diagram section, model-specific exploded views, three symptom/cause/corrective-action troubleshooting tables, maintenance schedules, and tables for torque, capacities, clearances, wear limits, shims, and electrical tests.

This 330-page PDF addresses marine owners and mechanics and assumes basic mechanical ability while explaining tools and techniques for someone using a shop manual for the first time. It is best suited to an experienced owner or repair technician with the proper electrical test equipment, pullers, measuring tools, and safe lifting and support equipment. Precision powerhead, gearcase, and hydraulic work calls for more than entry-level repair experience.

Model and Configuration Coverage

Coverage is divided by engine family rather than horsepower alone. The tables distinguish 2.5A/3.5A/3.5B, 9.9D/D2, 15D/D2, 18E/E2, 25C2/C3, 30A3/A4, the two- and three-cylinder 40 hp designs, 50D/D2, 60B/70B versus 60C/70C, and 80/90/115/120/140 applications. The manual also separates recoil and electric starting systems, tiller and remote controls, optional lighting and charging arrangements, and the 40/50 hp trim unit from the old- and new-style 60-140 hp power trim/tilt systems.

The engine-specific repair material is for carbureted two-stroke outboards. The general pages explaining four-stroke operating principles do not provide repair coverage for later four-stroke or EFI models.

Diagnostic and Service Depth

The diagnostic material goes well beyond generic no-start checks. It covers peak-voltage and resistance testing for exciter, pulser, ignition-coil, and CDI circuits, along with starter cranking, voltage-drop, alternator, and rectifier/regulator tests. Separate procedures address the warning horn, overheat, water-pressure, and oil-level sensors; speed-limiter inputs; trim solenoids, switches, sender, and gauge circuits; cooling faults; and gearcase pressure testing. Three structured troubleshooting tables organize starting, ignition, and fuel-system symptoms by likely cause and corrective path.

Fuel-system repair includes portable tanks, filters, primer bulbs, diaphragm pumps, carburetor disassembly and inspection, float setting, intake manifolds, and reed valves. Powerhead inspection data covers cylinder bores, piston clearance, ring end gap, crankshaft dimensions and runout, and connecting-rod bearings. The gearcase chapter adds bearing and seal work, gear and clutch inspection, shim selection, propeller-shaft runout, and final pressure and shift checks.

Model-specific reference tables collect ignition timing, test-propeller applications, carburetor settings, idle and trolling data, spark-plug applications, cylinder compression, torque specifications, lubrication data, battery requirements, electrical test values, trim-system specifications, and wear limits. Named special tools include flywheel puller/holding tool P/N 3C7-72211-0 and needle-bearing puller kit P/N 3C7-72700-0.

Diagrams, Wiring, and Repair Cautions

Exploded and component views cover fuel pumps and carburetors; alternator, pulser-coil, and CDI layouts; one-, two-, three-, and four-cylinder powerheads; model-specific water pumps and gearcases; and the 40/50 hp and old/new 60-140 hp trim/tilt units. The wiring section includes EF, EP, EFO, EFTO, and EPTO configurations. The 115 hp circuitry is split before serial 003-11050-3 and from that serial onward, which matters when tracing control, sensor, and instrument wiring.

The gearcase sliding clutch is asymmetrical, and installing it backward can damage the clutch and gears. Used reed valves must not be flipped over for reuse because a fractured reed can cause serious powerhead damage.

The trim chapter covers unit removal and installation, cylinder service, the manual relief valve, trim sender, fluid filling and bleeding, and specifications; it directs major hydraulic-component repair to a marine repair facility. Several tests require a running outboard, and trim service leaves the engine raised, so the manual’s cooling-water, propeller, battery-isolation, pressure-release, and positive-support precautions are integral to safe repair work.