2008 Yamaha F300, LF300, F350, LF350 Outboard Service & Repair Manual (P/N LIT-18616-03-08)

This Yamaha service manual covers the 2008 F300, LF300, F350, and LF350 outboards in regular- and counter-rotation configurations. Publication LIT-18616-03-08, first edition, February 2008, covers maintenance, electrical diagnosis, and mechanical repair.

• Power unit: Removal and installation, timing-belt replacement, valve-clearance adjustment, cylinder-head service, and crankshaft and bearing inspection.

• Fuel and cooling: Fuel-pressure testing, vapor-separator service, injector checks, thermostat inspection, and fuel, vapor-gas, and cooling-water hose routing.

• Electrical troubleshooting: ECM coupler layouts, Electronic Throttle Valve (ETV) and shift-actuator tests, ignition and charging checks, and trouble-code checking charts.

• Lower unit: Water-pump service, separate regular- and counter-rotation teardown procedures, shaft and bearing work, gear-backlash measurement, and shim selection tables.

• Bracket and PTT: Steering-arm and swivel-bracket service, Power Trim and Tilt hydraulic pressure testing, motor and gear-pump repair, cylinder inspection, and bleeding.

• Rigging and maintenance: Digital Electronic Control reset, tilt-limiter setup, network diagrams, predelivery checks, and periodic service schedules.

Yamaha prepared this manual primarily for dealers and trained mechanics with YTA Bronze marine certification or an equivalent understanding of mechanical and electrical service procedures.

ECM Diagnosis and Digital Electronic Control

The technical chapters explain variable camshaft timing, fuel-injection control logic, ion-knock detection, and fail-safe operation. ECM pinouts, sensor voltage charts, and fault-specific checking tables help distinguish wiring faults from sensor or actuator problems before replacement decisions.

The Yamaha Diagnostic System (YDIS) section identifies kit 60V-85300-04 and describes diagnosis records, engine monitoring, stationary and active tests, and ECM record-data graphs. It provides model-specific information; detailed software operation is covered in the separate YDIS Instruction Manual.

Digital network diagrams distinguish single-, twin-, and triple-outboard installations with Command Link Multifunction Meters. Control-box and switch-panel installation procedures are assigned to the separate Digital Electronic Control service manual.

Fuel Supply, Throttle Testing, and Cooling

Fuel-system coverage follows the low- and high-pressure pumps, pressure regulator, vapor separator, and vapor shut-off system. Exploded views support float and needle-valve inspection, while pressure tests and hose-routing views address fuel delivery and vapor handling.

The ETV and its throttle position sensors are tested as an assembly; the manual states that this unit cannot be disassembled. Fuel recommendations distinguish regular unleaded for F300/LF300 from premium unleaded for F350/LF350.

Cooling-water flow diagrams trace the thermostats, fuel cooler, and water-cooled rectifier/regulator. Periodic maintenance also covers anodes, NGK LFR6A-11 spark plugs, and oil/filter service, with refill quantities distinguished from total oil-pan capacity.

Timing, Cylinder Heads, and Internal Engine Repair

The power-unit chapters pair exploded assemblies with removal, inspection, and installation instructions. Internal work includes valve-guide replacement, valve-seat refacing, piston and ring inspection, and connecting-rod and main-bearing selection, supported by torque tables and wear limits.

Timing and flywheel cautions address possible impeller damage from reverse rotation and piston/valve or valve-to-valve contact with the timing belt removed. Flywheel reassembly also calls for new bolts.

Always reference the complete factory specifications and safety procedures before fuel-pressure work or power-unit lifting.

Rotation-Specific Shimming and PTT Overhaul

The regular-rotation section assigns T1 to the forward-gear shim and T2 to the reverse-gear shim. Counter-rotation coverage reverses those assignments and adds T4 propeller-shaft shimming and free-play measurement.

PTT coverage extends to relief-valve and gear-pump components, motor brushes and commutator inspection, and tilt/trim ram seals. Separate bleeding procedures address the removed assembly and the unit installed on the outboard.

The color wiring appendix separates engine-control, fuel, ignition, charging/starting, and PTT circuits, with connector numbers and wire-color codes.

A Preview of Cylinder-Head and Compression Data

These engine inspection values are a small selection of the service limits and reference data in the manual. Cylinder-head warpage is limited to 0.1 mm (0.0039 in).

Minimum compression is listed as reference data at 740 kPa (107.3 psi). The stated conditions include a warmed engine, 20°C ambient temperature, Digital Electronic Control in neutral, and all spark plugs removed.

Searchable Text, Bookmarks, and Wiring-Sheet Detail

Text navigation and wiring labels: Searchable PDF text and embedded bookmarks provide access to chapters and individual procedures. Small connector numbers and wire-color labels in the wide wiring diagrams require zooming.

One printable, English-language 572-page PDF contains the service manual and its wiring appendix. The total already includes two cover pages and four blank pages.