TOHATSU MFS 3.5C User Manual (English)

Questions and Answers:

M
Mark Preston Jr.Aug 3, 2025
What to do if my TOHATSU Outboard Motor starts but stops soon after?
- J
  James GregoryAug 3, 2025
  If your TOHATSU Outboard Motor starts but then stops quickly, several factors could be at play. It might be due to a deformed or damaged fuel hose, in which case you should check and replace it. Another cause could be a closed air vent on the fuel tank; make sure to open it. Additionally, a clogged fuel filter, fuel pump, or carburetor could be the issue, so clean or replace these components. Using the incorrect engine oil or gasoline can also lead to this problem, so ensure you're using the recommended types. Finally, an excessive fuel supply or poor carburetor adjustment may be to blame; adjust these accordingly.
R
Rebecca AndersonAug 7, 2025
Why is my TOHATSU MFS 3.5C Outboard Motor overheating?
- A
  andreschneiderAug 7, 2025
  Engine overheating in your TOHATSU Outboard Motor can stem from several causes. Insufficient cooling water flow, possibly due to a clogged or defective pump, is a common culprit, so check the cooling system. Other potential issues include a faulty thermostat (replace it), cavitation or ventilation problems (correct these), an incorrect propeller (select the correct one), or a damaged propeller (repair or replace it). Also, verify that the thrust rod position is properly adjusted, the load on the boat is balanced, and the transom height is correct.
M
Michael ClarkAug 11, 2025
What causes poor acceleration in a TOHATSU MFS 3.5C?
- K
  Kayla CummingsAug 11, 2025
  Poor acceleration in your TOHATSU Outboard Motor can be caused by several factors related to ignition and fuel. Check the spark plug for dirt or soot and clean it if necessary. A weak or absent spark could also be the issue, so inspect the ignition system. Additionally, a short circuit in the engine stop switch or incorrect ignition timing may be to blame; inspect the switch and adjust the timing accordingly.
D
David RomeroAug 16, 2025
Why is my TOHATSU Outboard Motor idling poorly?
- V
  Victoria DiazAug 16, 2025
  Poor idling in your TOHATSU Outboard Motor can arise from several issues. The spark plug may be dirty with soot, so cleaning it is a good first step. A weak or nonexistent spark could also be the cause, requiring a check of the ignition system. Other potential problems include a short circuit in the engine stop switch (inspect it), incorrect ignition timing (adjust it), a missing lock plate on the stop switch (fit the lock plate), or disconnected wires/loose ground connections (check and secure all connections).
J
Jeffrey JohnsonAug 19, 2025
What to do if the engine speed of my TOHATSU Outboard Motor is abnormally high?
- M
  Michelle WilliamsAug 20, 2025
  An abnormally high engine speed in your TOHATSU Outboard Motor could be due to several reasons. One potential cause is using the incorrect engine oil, so ensure you are using the correct type. Another reason might be a closed air vent on the fuel tank; open it to resolve this. Also, poor carburetor adjustment can lead to high engine speeds, so adjusting the carburetor may be necessary.
J
John FigueroaAug 25, 2025
Why is the engine speed of my TOHATSU Outboard Motor abnormally low?
- H
  Heidi ScottAug 25, 2025
  If your TOHATSU Outboard Motor's engine speed is abnormally low, it could be related to the fuel system or the type of gasoline you're using. You should check the fuel system, because there might be need to clean or replace the fuel filter, fuel pump, or carburetor. Also, ensure you are using the recommended gasoline.
G
guerrajohnAug 28, 2025
What causes low boat speed in a TOHATSU Outboard Motor?
- J
  John WoodwardAug 28, 2025
  Low boat speed with your TOHATSU Outboard Motor can be attributed to a couple of factors. First, ensure you are using the correct oil. Second, the throttle link might be incorrectly adjusted, so adjust it accordingly.

TOHATSU MFS 3.5C Specifications

General

Engine Type	2-Stroke
Power Output	3.5 HP
Starting	Manual
Fuel Type	Gasoline
Gear Ratio	2.15:1
Oil/Fuel Ratio	50:1
Full Throttle RPM Range	5000-6000 RPM
Gear Shift	Forward, Neutral
Shaft Length	15 in
Fuel Consumption	1.0 L/h

Summary

Your Tohatsu Outboard Motor

To You, Our Customer

Welcome message from Tohatsu Corporation.

Owner Registration and Identification

Importance of warranty card registration for ownership.

Pre-Delivery Check

Ensure the product is checked by a dealer before delivery.

Serial Number

Recording Serial Number

Space to record the outboard motor's serial number for inquiries.

Safety Notices

Understanding Safety Indicators

Explains the meaning of DANGER, WARNING, CAUTION, and Note.

GENERAL SAFETY INFORMATION

Safe Boat Operation

Operator responsibility for safety and following regulations.

Stop Switch Lanyard Usage

How to use the stop switch lanyard for safety.

Personal Flotation Device (PFD)

Requirement to wear a PFD while on the boat.

Servicing, Replacement Parts, and Lubricants

Recommendations for service, parts, and lubricants.

Maintenance Responsibility

Owner's responsibility for safety checks and maintenance.

Health Hazards

Warnings about carbon monoxide and gasoline hazards.

SPECIFICATIONS

Model Feature Overview

Table outlining features for different models.

Model Name Example

Explanation of the model naming convention.

PARTS NAME

Identification of Parts

Diagram identifying key parts of the outboard motor.

LABEL LOCATIONS

Warning Label 1: Owner's Manual

Label indicating the need to read the owner's manual.

Warning Label 2: Stop Switch

Label warning about the stop switch usage.

Warning Label 3: High Temperature

Warning label regarding high temperature hazards.

Warning Label 4: Rotating Parts & Voltage

Label warns about rotating parts and high voltage.

Warning Label 5: Fuel Tank Cap

Label warning regarding fuel tank cap safety.

ECI Label Locations

Location of Emission Control Information labels.

INSTALLATION

Mounting the Outboard Motor on Boat

Instructions for securely mounting the motor on the boat's transom.

Altitude Adjustment Kit Requirement

When a high altitude kit is needed for engine operation.

PRE-OPERATING PREPARATIONS

Fuel Handling Safety

Guidelines for safe handling of gasoline and fuel.

Fuel Filling Procedures

Safe steps for filling the fuel tank.

Engine Oil Filling

Instructions for filling the engine with oil before operation.

Engine Oil Recommendation and Volume

Specifies recommended oil type, viscosity, and volume.

Engine Break-In Procedure

Steps for breaking in the new outboard motor.

ENGINE OPERATION

Oil Level Checking

Check engine oil level before each use for optimal performance.

Fuel Feeding

Procedure for supplying fuel to the engine, including tank cap operation.

Starting the Engine

Step-by-step guide for starting the engine.

Engine Starting Steps

Setting controls, pulling starter, and checking cooling water.

Emergency Starting Procedure

Instructions for starting the engine in an emergency.

Warming Up the Engine

Proper procedure for warming up the engine to ensure lubrication.

Forward, Reverse, and Acceleration

How to shift gears and control speed for operation.

Tiller Handle Operation

Specific controls and actions for tiller handle models.

Stopping the Engine

Safe procedures for stopping the outboard motor.

Steering Operation

How to steer the outboard motor using the tiller handle.

Trim Angle Adjustment

Adjusting the trim angle for optimal boat performance.

Tilt Up and Down

Procedures for tilting the outboard motor up and down.

REMOVING AND CARRYING THE OUTBOARD MOTOR

Removing the Outboard Motor

Steps to safely remove the motor from the boat.

Carrying the Outboard Motor

Guidelines for safely carrying the outboard motor.

Trailering Procedures

Instructions for trailering the boat with the motor attached.

ADJUSTMENT

Steering Friction Adjustment

Adjusting steering friction for preferred feel.

Throttle Grip Friction Adjustment

Adjusting throttle grip friction.

INSPECTION AND MAINTENANCE

Outboard Motor Care

General advice for maintaining the motor's condition.

Daily Inspection Checklist

Routine pre- and post-use checks.

Engine Oil Level Checking and Replenishing

Procedures for checking and adding engine oil.

Washing and Flushing the Motor

How to wash and flush the outboard motor.

Flushing by Test Tank

Procedure for flushing using a test tank.

Periodic Inspection Schedule

Detailed maintenance schedule based on hours/months.

Engine Oil Replacement

Step-by-step guide for changing engine oil.

Gear Oil Replacement

Procedure for changing gear oil in the lower unit.

Propeller Replacement

Instructions for replacing the propeller.

Spark Plugs Replacement

Guide for replacing spark plugs.

Anode Replacement

Procedure for replacing the sacrificial anode.

Grease Points

Locations for applying waterproof grease.

Off-Season Storage Preparation

Steps for preparing the motor for long-term storage.

Adding Fuel Stabilizer

How to add fuel stabilizer for storage.

Fuel System Draining

Procedure for draining the fuel system.

Pre-Season Check

Checks before first use after storage.

Submerged Outboard Motor

Emergency measures for a submerged motor.

Cold Weather Precautions

Measures to prevent cold weather damage.

Striking Underwater Object

Actions to take after hitting an object.

Auxiliary Outboard Motor Operation

Specific operating guidance for auxiliary motors.

TROUBLESHOOTING

TOOL KIT AND SPARE PARTS

Provided Tools and Spare Parts

List of tools and spare parts included with the motor.

PROPELLER TABLE

Propeller Selection Guide

Guidance on selecting the correct propeller based on boat type and RPM.

EMISSION CONTROL SYSTEM INFORMATION

Emission Sources and Control

Explains emission sources and ignition timing control.

Compliance with Air Acts

Regulations for emission control systems.

Tampering and Modifications Warning

Warning against tampering with emission control systems.

Symptoms Affecting Emissions

Symptoms indicating potential emission control issues.

Replacement Parts Recommendation

Importance of using genuine replacement parts.

Low Permeation Fuel Hose Requirement

EPA requirement for fuel hoses in US/Canada.

EPA Pressurized Fuel Tank Requirements

EPA requirements for portable fuel tanks.

Star Label Description

Explanation of the CARB star label.

One Star-Low Emission Standard

Details of the one-star emission standard.

Two Stars-Very Low Emission

Standard for two-star emission engines.

Four Stars-Super Ultra Low Emission

Standard for four-star emission engines.

Three Stars-Ultra Low Emission

Standard for three-star emission engines.

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