Contents General information 0 Specification 1 Technical features and description 2 Rigging information 3 Troubleshooting 4 Electrical system 5 Fuel system 6 Power unit 7 Lower unit 8 Bracket unit 9 Maintenance 10 Index Appendix A GEN INFO SPEC TECH FEA RIG GING TRBL SHTG ELEC FUEL POWR LOWR BRKT MNT
GEN INFO 0 1 2 3 4 5 6 7 8 9 10 A General information 0 Safety while working ........................................................... 0-1 Rotating part .............................................................................. 0-1 Hot part ...................................................................................... 0-1 Electric shock ............................................................................ 0-1 Propeller .................................................................................... 0-1 Handling of gasoline .................................................................. 0-1 Ventilation .................................................................................. 0-1 Self-protection ........................................................................... 0-2 Working with crane .................................................................... 0-2 Handling of burner ..................................................................... 0-2 Part, lubricant, and sealant ........................................................ 0-2 Handling of sealant .................................................................... 0-2 Special service tool ................................................................... 0-3 Tightening torque ...................................................................... 0-3 Non-reusable part ...................................................................... 0-3 Disassembly and assembly ....................................................... 0-3 How to use this manual ........................................................... 0-4 Manual format ........................................................................... 0-4 Abbreviation .............................................................................. 0-5 Sealant and locking agent ...................................................... 0-7 Symbol ...................................................................................... 0-7 Special service tool .................................................................. 0-9
0-1 GEN INFO General information Safety while working To prevent an accident or injury and to ensure quality service, follow the safety pro- cedures provided below. Rotating part • Hands, feet, hair, jewelry, clothing, personal flotation device straps, and so on can become entangled with internal rotating parts of the engine, resulting in serious injury or death. • Keep the top cowling in place whenever possible. Do not remove or replace the cowling with the engine running. • Only operate the engine with the cowling removed according to the specific instruc- tions in the manual. Keep hands, feet, hair, jewelry, clothing, personal flotation device straps, and so on away from any exposed moving parts. Hot part During and after operation, engine parts are hot enough to cause burns. Avoid touching any parts under the top cowling until the engine has cooled. Electric shock Do not touch any electrical parts while start- ing or operating the engine. They can cause shock or electrocution. Propeller Do not hold the propeller with your hands when loosening or tightening it. Handling of gasoline • Gasoline is highly flammable. Keep gaso- line and all flammable products away from heat, sparks, and open flames. • Gasoline is poisonous and can cause injury or death. Handle gasoline with care. Never siphon gasoline by mouth. If you should swallow some gasoline or inhale a lot of gasoline vapor, or get some gasoline in your eyes, see your doctor immediately. If gasoline spills on your skin, wash with soap and water. If gasoline spills on your cloth- ing, change your clothes. Ventilation • Gasoline vapor and exhaust gas are heavier than air and extremely poisonous. If inhaled in large quantities they may cause loss of consciousness and death within a short time. • When test running an engine indoors (example: in a water tank), be sure to do so where adequate ventilation can be main- tained.
0-2 Safety while working 0 1 2 3 4 5 6 7 8 9 10 A Self-protection • Protect your eyes by wearing safety glasses or safety goggles during all opera- tions involving drilling and grinding, or when using an air compressor. • Protect your hands and feet by wearing pro- tective gloves and safety shoes when nec- essary. Working with crane • Outboard motors weighing 18.0 kg (39.7 lb) and over must be carried by a crane. • Use a wire rope of adequate strength, and lift up the outboard motor with the three point suspension. • If the outboard motor does not have three or more points to be suspended, support it with additional ropes or the like so that the outboard motor can be lifted and carried in a stable manner. Handling of burner • Incorrect handling of burner may result in burns. Refer to the operation manual issued by the manufacturer to assure the correct handling. • When using a burner, keep it away from the gasoline and oil, to prevent a fire. • Components become very hot enough to cause burns. Do not touch directly. Part, lubricant, and sealant Use only genuine Yamaha parts, lubricants, and sealants or those recommended by Yamaha, when servicing or repairing the out- board motor. Handling of sealant • Wear protective gloves to protect your skin, when using the sealants. • Refer to the material data sheet issued by the manufacturer. Some of the sealants may be harmful for human health.
0-3 GEN INFO General information Special service tool Use the recommended special service tools to work safety, and to protect parts from dam- age. Tightening torque Follow the tightening torque specifications provided throughout the manual. When tight- ening nuts, bolts, and screws, tighten the large sizes first, and tighten fasteners starting in the center and moving outward. Non-reusable part Always use new gaskets, seals, O-rings, cot- ter pins, circlips, and so on, when installing or assembling parts. Disassembly and assembly • Use compressed air to remove dust and dirt during disassembly. • Apply engine oil to the contact surfaces of moving parts before assembly. • Install bearings with the manufacture identi- fication mark in the direction indicated in the installation procedure. In addition, be sure to lubricate the bearings liberally. • Apply a thin coat of water-resistant grease to the lip and periphery of an oil seal before installation. • Check that moving parts operate normally after assembly.
0-4 0 1 2 3 4 5 6 7 8 9 10 A How to use this manual Manual format The format of this manual has been designed to make service procedures clear and easy to under- stand. Use the information below as a guide for effective and quality service. • Parts are shown and detailed in an exploded diagram and are listed in the component list (see a in the figure below for an example page). • The component list consists of part names and quantities, as well as bolt and screw dimensions (see b in the figure below). • Symbols are used to indicate important aspects of a procedure, such as the grade of lubricant and lubrication point (see c in the figure below). • Tightening torque specifications are provided in the exploded diagrams (see d in the figure below for an example), and in the related detailed instructions. Some torque specifications are listed in stages as torque figures or angles in degrees. • Separate procedures and illustrations are used to explain the details of removal, checking, and installation where necessary (see e in the figure below for an example page). TIP: For troubleshooting procedures, see Chapter 4, “Troubleshooting.” 8-1 LOWR Lower unit Lower unit (regular rotation model) A U-transom model No. Part name Q’ty Remarks 1 Water inlet cover (PORT) 1 2 Bolt 1 M5 × 40 mm 3 Gasket 2 Not reusable 4 Drain screw 1 5 Water inlet cover (STBD) 1 6 Self-locking nut 1 7 Check screw 1 8 Dowel 2 9 Plate 1 10 Rubber seal 1 11 Bolt 1 M10 × 45 mm 12 Grommet 1 13 Lower unit 1 14 Spacer 1 15 Propeller 1 16 Cotter pin 1 Not reusable 17 Propeller nut 1 14 20 22 1 2 22 13 15 18 16 19 17 22 21 11 12 25 26 24 6 3 7 8 9 10 8 5 4 3 23 34 33 32 31 30 29 25 35 27 28 42 N m (4.2 kgf m, 31.0 ft lb) 54 N m (5.4 kgf m, 39.8 ft lb) 47 N m (4.7 kgf m, 34.7 ft lb) 9 N m (0.9 kgf m, 6.6 ft lb) 9 N m (0.9 kgf m, 6.6 ft lb) 2.3 N m (0.23 kgf m, 1.70 ft lb) 47 N m (4.7 kgf m, 34.7 ft lb) A 8-19 LOWR Lower unit 2. Heat the installation area of the taper roller bearing outer race in the lower case with a gas torch, and then install the outer race b. NOTICE: When heating the lower case, heat the entire installation area evenly. Otherwise, the paint on the lower case could be burned. TIP: Do not reuse a shim if it is any deformed or scratched. 3. While holding the special service tool c, strike the tool to check that the taper roller bearing outer race is installed properly. If a high-pitched metallic sound is produced when the special service tool is struck, the outer race is installed properly. 4. Install the rollers into the needle bearing outer race, and install the special service tool into the needle bearing assembly e, and then install the needle bearing assembly e. TIP: The needle bearing contains 28 rollers. Assembling the forward gear Do not reuse the bearing, always replace it with a new one. 1. Install a new taper roller bearing. Driver rod LL c: 90890-06605 Bearing outer race attachment d: 90890-06658 a b c c d d Ball bearing attachment f: 90890-06655 Bearing outer race puller assembly g: 90890-06523 Bearing inner race attachment a: 90890-06659 f g e a e b c d a Safety while working / How to use this manual
0-5 GEN INFO General information Abbreviation The following abbreviations are used in this service manual. Abbreviation Description ABYC American Boat and Yacht Council AFT Aft end API American Petroleum Institute ATDC After Top Dead Center AWG American Wire Gauge BL Backlash BOW Bow end BTDC Before Top Dead Center CA Crank Angle CARB California Air Resources Board CCA Cold Cranking Ampere C/E Check Engine C/L Centerline DN Down side ECM Electronic Control Module ENG Engine EPA Environmental Protection Agency ETV Electronic Throttle Valve EX Exhaust F Forward IN Intake ISC Idle Speed Control LPS Lever Position Sensor M Measurement M.E.S. Multi Engine System N Neutral OCV Oil Control Valve PCV Pressure Control Valve PON Pump Octane Number = (RON + Motor Octane Number) / 2 PORT Port side PTT Power Trim and Tilt R Reverse R.C. Remote Control (Digital Electronic Control) SAE Society of Automotive Engineers SM Service Manual SPS Shift Position Sensor STBD Starboard side SW Switch
The Yamaha F250B/LF250B Outboards Service & Repair Manual is an authoritative guide for maintaining and repairing these specific outboard models. Sourced directly from the manufacturer, it provides comprehensive details covering everything from routine maintenance schedules to in-depth troubleshooting procedures for electrical and mechanical systems.
With detailed diagrams and technical specifications, the manual ensures you have the precise information necessary for accurate diagnostics and repairs. Topics include fuel system inspection, powerhead disassembly, and electrical component diagnostics, providing clarity on each system’s operation. Torque specifications, wiring diagrams, and maintenance intervals help ensure smooth operation and prolonged engine life.
Whether you're a marine technician or a DIY enthusiast, this manual is structured to address all your repair needs efficiently. From basic servicing to major overhauls, it delivers accurate instructions to help keep your Yamaha F250B/LF250B outboards in optimal condition.
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Language: English
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Yamaha F250B/LF250B Outboards OEM Service & Repair Manual