TOHATSU MFS 9.8B User Manual (English)

Other manuals for TOHATSU MFS 9.8B

Questions and Answers:

L
Laura PattersonAug 6, 2025
Why is my TOHATSU MFS 9.8B Outboard Motor engine failing to start?
- C
  Carl CampbellAug 7, 2025
  If your TOHATSU Outboard Motor engine fails to start, possible causes include an empty fuel tank (fill it), incorrect fuel system connections (check them), air in the fuel line (inspect for leaks), a deformed fuel hose (replace it), a closed air vent on the fuel tank (open it), clogged fuel filter/pump/carburetor (clean or replace), improper engine oil/gasoline (use recommended types), excessive fuel supply (adjust), or poor carburetor adjustment (adjust).
R
Rita PonceAug 11, 2025
How to fix poor idling on my TOHATSU MFS 9.8B?
- A
  Alyssa RojasAug 12, 2025
  Poor idling in your TOHATSU Outboard Motor can be caused by a low oil level (check and replenish), carbon deposits in the combustion chamber (clean the chamber), or incorrect valve clearance (adjust the valve clearance).
D
debrastevensAug 16, 2025
Why does my TOHATSU Outboard Motor have poor acceleration?
- T
  Thomas LloydAug 16, 2025
  Poor acceleration in your TOHATSU Outboard Motor may be due to low oil pressure or level (check both) or incorrect adjustment of the throttle link (adjust the throttle link).
D
David DownsAug 22, 2025
What causes abnormally high engine speed on a TOHATSU MFS 9.8B?
- M
  Margaret SandovalAug 22, 2025
  If your TOHATSU Outboard Motor's engine speed is abnormally high, it might be due to dirt or soot on the spark plug (clean it) or cavitation/ventilation issues (inspect and remedy them).
P
Patrick SandersAug 27, 2025
What to do if TOHATSU MFS 9.8B Outboard Motor engine starts but stops immediately?
- S
  Seth BerryAug 27, 2025
  If your TOHATSU Outboard Motor engine starts but stops soon after, it could be due to several reasons. These include low compression (check compression levels), a dirty spark plug (clean it), a faulty oil pressure switch (replace it), no or weak spark (inspect the ignition system), a short circuit in the engine stop switch (check for shorts), incorrect ignition timing (adjust it), missing lock plate (install it), disconnected wire or loose ground (reconnect or secure), a blown fuse (replace it), not shifted to neutral (shift to neutral), weak battery or loose connections (check and secure), ignition key switch failure (replace it), faulty wiring (inspect and repair), or starter motor/solenoid failure (replace them).
G
Garrett AlexanderSep 1, 2025
Why is my TOHATSU MFS 9.8B overheating?
- P
  Patrick MosesSep 1, 2025
  If your TOHATSU Outboard Motor is overheating, it could be due to insufficient cooling water flow from a clogged or defective pump (inspect, repair, or replace the water pump) or a faulty thermostat (replace the thermostat).

TOHATSU MFS 9.8B Specifications

General

Brand	TOHATSU
Model	MFS 9.8B
Category	Outboard Motor
Language	English

Summary

GENERAL SAFETY INFORMATION

Safe Boat Operation Practices

Operator responsibilities for safe handling and knowledge of regulations.

Emergency Stop Switch Usage

Functionality and importance of the emergency stop switch lanyard.

Personal Flotation Device (PFD) Requirement

Mandate for operators and passengers to wear PFDs.

ADDITIONAL SAFETY GUIDELINES

Hazard: Carbon Monoxide Poisoning

Risks of carbon monoxide gas and ventilation needs.

Hazard: Gasoline Flammability

Risks associated with gasoline and safe handling practices.

OUTBOARD MOTOR INSTALLATION

Motor Mounting on Boat

Procedures for securely mounting the outboard motor on a boat.

Installation Safety Warnings

Warnings regarding boat capacity and secure motor mounting.

REMOTE CONTROL AND CABLE INSTALLATION

Remote Control Device Installation

Procedures for installing the remote control system components.

BATTERY INSTALLATION AND SAFETY

Battery Installation Guide

Step-by-step instructions for installing the battery.

Battery Handling and Charging Hazards

Warnings about battery gases and safe charging practices.

Battery Connection Precautions

Cautions regarding correct battery connections and operation.

PRE-OPERATING PREPARATIONS: FUEL

Fuel Handling and Storage Guidelines

Safe practices for handling and storing fuel.

FUEL HANDLING AND FILLING PROCEDURES

Fuel Leakage and Fire Hazards

Warnings regarding the risks of fuel leaks.

Fuel Filling Safety Precautions

Essential safety steps for filling the fuel tank.

Fuel Tank Cap Opening Caution

Cautionary advice for opening the fuel tank cap.

FUEL FILLING AND ENGINE OIL

Fuel Tank Filling Procedure

Detailed steps for filling the fuel tank.

Engine Oil Recommendations

Guidance on the correct type and viscosity of engine oil.

Engine Oil Quality Caution

Importance of using the specified engine oil quality.

ENGINE BREAK-IN PROCEDURE

Outboard Motor Break-In Requirements

Schedule and importance of breaking in new motors.

Break-In Environment Safety

Safety warnings for break-in operation environment.

Break-In Performance Caution

Risks of operating the motor without proper break-in.

WARNING SYSTEMS AND INDICATORS

Outboard Motor Warning System

Explanation of how warning horns and lamps function.

WARNING INDICATORS AND REMEDIES

Warning Indicators, Faults, and Remedies

Table detailing warning signals, faults, and corrective actions.

WARNING INDICATOR REMEDY ACTIONS

Corrective Actions for Warning Indicators

Specific steps to take when warning indicators activate.

ESG Operation Cautions

Cautions regarding engine speed limits during ESG activation.

ENGINE OPERATION: BEFORE STARTING

Pre-Start Engine Checks

Essential checks before starting the engine, including oil and fuel lines.

Fuel Feeding Procedure

Steps to supply fuel to the engine from the tank.

Fuel Tank Cap Opening Caution

Cautionary advice for safely opening the fuel tank cap.

ENGINE OPERATION: STARTING THE ENGINE

Starting the Engine Safely

Procedures for safely starting the outboard motor.

Cooling Water Intake Check

Importance of checking water flow for cooling during starting.

Starter Motor Operation Limits

Cautions regarding the duration of starter motor use.

ENGINE OPERATION: ELECTRIC STARTING

Starter Motor Safety Caution

Warning regarding the duration of starter motor operation.

ENGINE OPERATION: CONTROL LEVER AND STARTING

Emergency Starting Procedure

Steps for starting the engine using the emergency starter rope.

Emergency Starting Safety Warning

Critical safety points for emergency rope starting.

ENGINE OPERATION: WARMING UP

Engine Warm-Up Procedure

Importance and steps for warming up the engine.

Warm-Up Cooling Water Caution

Caution regarding checking water flow during engine warm-up.

ENGINE OPERATION: SPEED AND GEAR SHIFTING

Shifting Safety Precautions

General safety warnings related to gear shifting.

Shifting at High Speed Caution

Caution regarding the risks of shifting at high boat speeds.

Shifting During Warm-Up Caution

ENGINE OPERATION: ACCELERATION AND GEARS

Neutral and Reverse Speed Caution

Acceleration and Deceleration Safety

Safety warnings regarding sudden changes in speed.

ENGINE OPERATION: FORWARD, REVERSE, AND STOPPING

Engine Stopping Procedure

Stop Switch Lanyard Safety

Importance of keeping the stop switch lanyard attached.

ENGINE OPERATION: STEERING

Steering Operation Guide

Steering Safety Warning

Warnings about the risks of sudden steering inputs.

ENGINE OPERATION: TRIM ANGLE

Trim Angle Adjustment Overview

Trim Adjustment Safety Warnings

Warnings about dangers during trim angle adjustment.

TRIM AND TILT OPERATIONS

Tilting Up and Down Safety

Safety warnings related to tilting the motor up or down.

Power Tilt Oil Checking

TILTING AND SHALLOW WATER OPERATIONS

Manual Relief Valve Safety Warning

Shallow Water Operation Basics

Shallow Water Operation Safety

Safety warnings specific to shallow water operation.

SHALLOW WATER OPERATION PROCEDURES

Shallow Water Drive Caution

REMOVING AND CARRYING THE OUTBOARD MOTOR

Removing the Outboard Motor

Carrying the Outboard Motor Safely

Transport and Fuel Handling Warnings

Warnings about fuel leaks and damage during transport.

TRANSPORTING AND TRAILERING THE OUTBOARD MOTOR

Traillering Precautions and Warnings

TRAILERING SAFETY AND SUPPORT

Traillering Safety Warning

Safety warning regarding going under a tilted outboard motor.

ADJUSTMENT PROCEDURES

Steering Friction Adjustment

Throttle Grip Friction Adjustment

Remote Control Lever Friction

ADJUSTMENTS AND TRIM TAB SETTINGS

Trim Tab Adjustment Guide

INSPECTION AND MAINTENANCE: OVERVIEW

Maintenance Safety and Importance

DAILY INSPECTION CHECKLIST

Daily Inspection Procedures

Pre-Operation Check Warning

Warning against operating the motor with any abnormalities.

OIL LEVEL CHECKING AND REPLENISHING

Engine Oil Level Checking

Engine Oil Replenishing Procedure

Engine Oil Addition Safety Cautions

MOTOR WASHING AND FLUSHING

Washing the Outboard Motor

Engine Washing Safety Warnings

Safety warnings related to washing the engine and components.

FLUSHING AND FUSE REPLACEMENT

Test Tank Operation Safety Warnings

Safety warnings for operating the motor in a test tank.

Fuse Replacement Procedure and Safety

PERIODIC INSPECTION SCHEDULE

Periodic Inspection Intervals and Tasks

ENGINE OIL REPLACEMENT PROCEDURE

Engine Oil Replacement Steps

Engine Oil Replacement Safety Cautions

ENGINE OIL REPLACEMENT DETAILS

Engine Oil Replacement Steps (Continued)

Spilled Oil Handling Caution

FUEL SYSTEM MAINTENANCE

Fuel Filters and Fuel Tank Cleaning

Gasoline and Fuel Handling Hazards

Safety warnings regarding flammable gasoline and fuel handling.

FUEL TANK FILTER AND GEAR OIL

Gear Oil Replacement Procedure

Gear Oil Replacement Safety Warning

Safety warning about securing the motor during oil change.

PROPELLER REPLACEMENT PROCEDURES

Propeller Replacement Safety

Safety warnings before starting propeller removal and installation.

Propeller Installation Cautions

PROPELLER AND SPARK PLUG REPLACEMENT

Propeller Replacement Steps

Spark Plugs Replacement Procedure

Spark Plug Safety Warnings

Safety warnings related to spark plug handling.

SPARK PLUG REPLACEMENT DETAILS

Spark Plug Replacement Steps (Continued)

ANODE REPLACEMENT PROCEDURE

Anode Replacement Guide

POWER TILT OIL CHECKING AND PURGING

Power Tilt Oil Checking Procedure

Power Tilt Safety Warnings

Safety warnings related to power tilt system operation.

LUBRICATION POINTS (GREASE)

Grease Point Locations

OFF-SEASON STORAGE PREPARATION

Off-Season Storage General Guidelines

Fuel Connector and Fuel Removal Warnings

Warnings about fuel handling during storage preparation.

FUEL STABILIZER AND STORAGE

Off-Season Storage Motor Placement

FUEL SYSTEM DRAINING AND BATTERY CARE

Fuel System Draining Procedure

Fuel Handling and Ventilation Warnings

Warnings about fuel hazards and necessary ventilation.

Battery Spark Hazard Warning

Warning about battery sparks near fuel tanks.

PRE-SEASON CHECKS AND SUBMERGED MOTOR

Pre-Season Check Steps

Submerged Outboard Motor Emergency Handling

Submerged Motor Start Caution

Caution against starting a submerged motor immediately.

TROUBLESHOOTING: FUEL AND ELECTRICAL SYSTEMS

Fuel System Troubleshooting Guide

Electrical System Troubleshooting Guide

TROUBLESHOOTING: ENGINE AND OTHER ISSUES

Engine Oil System Troubleshooting

Other Troubleshooting Categories

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TOHATSU MFS 9.8B User Manual

Table of Contents

Other manuals for TOHATSU MFS 9.8B

Questions and Answers:

TOHATSU MFS 9.8B Specifications

Summary

GENERAL SAFETY INFORMATION

Safe Boat Operation Practices

Emergency Stop Switch Usage

Personal Flotation Device (PFD) Requirement

ADDITIONAL SAFETY GUIDELINES

Hazard: Carbon Monoxide Poisoning

Hazard: Gasoline Flammability

OUTBOARD MOTOR INSTALLATION

Motor Mounting on Boat

Installation Safety Warnings

REMOTE CONTROL AND CABLE INSTALLATION

Remote Control Device Installation

BATTERY INSTALLATION AND SAFETY

Battery Installation Guide

Battery Handling and Charging Hazards

Battery Connection Precautions

PRE-OPERATING PREPARATIONS: FUEL

Fuel Handling and Storage Guidelines

FUEL HANDLING AND FILLING PROCEDURES

Fuel Leakage and Fire Hazards

Fuel Filling Safety Precautions

Fuel Tank Cap Opening Caution

FUEL FILLING AND ENGINE OIL

Fuel Tank Filling Procedure

Engine Oil Recommendations

Engine Oil Quality Caution

ENGINE BREAK-IN PROCEDURE

Outboard Motor Break-In Requirements

Break-In Environment Safety

Break-In Performance Caution

WARNING SYSTEMS AND INDICATORS

Outboard Motor Warning System

WARNING INDICATORS AND REMEDIES

Warning Indicators, Faults, and Remedies

WARNING INDICATOR REMEDY ACTIONS

Corrective Actions for Warning Indicators

ESG Operation Cautions

ENGINE OPERATION: BEFORE STARTING

Pre-Start Engine Checks

Fuel Feeding Procedure

Fuel Tank Cap Opening Caution

ENGINE OPERATION: STARTING THE ENGINE

Starting the Engine Safely

Cooling Water Intake Check

Starter Motor Operation Limits

ENGINE OPERATION: ELECTRIC STARTING

Starter Motor Safety Caution

ENGINE OPERATION: CONTROL LEVER AND STARTING

Emergency Starting Procedure

Emergency Starting Safety Warning

ENGINE OPERATION: WARMING UP

Engine Warm-Up Procedure

Warm-Up Cooling Water Caution

ENGINE OPERATION: SPEED AND GEAR SHIFTING

Shifting Safety Precautions

Shifting at High Speed Caution

Shifting During Warm-Up Caution

ENGINE OPERATION: ACCELERATION AND GEARS

Neutral and Reverse Speed Caution

Acceleration and Deceleration Safety

ENGINE OPERATION: FORWARD, REVERSE, AND STOPPING

Engine Stopping Procedure

Stop Switch Lanyard Safety

ENGINE OPERATION: STEERING

Steering Operation Guide

Steering Safety Warning

ENGINE OPERATION: TRIM ANGLE

Trim Angle Adjustment Overview

Trim Adjustment Safety Warnings

TRIM AND TILT OPERATIONS

Tilting Up and Down Safety

Power Tilt Oil Checking

TILTING AND SHALLOW WATER OPERATIONS

Manual Relief Valve Safety Warning