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Yamaha 55DEHD - User Manual

Yamaha 55DEHD
269 pages
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YAMAHA MOTOR CO., LTD.
Printed in Japan
Oct. 2006 – 1.1 × 1 !
(E_2)
Printed on recycled paper
75A
SERVICE MANUAL
688-28197-5J-11
85A
55D
55D, 75A, 85A
688_cover.qxd_1 07.9.26 16:21 Page 1

Table of Contents

Questions and Answers

  • D
    Daniel TaylorAug 3, 2025
    Why Yamaha 55DEHD PTT unit does not hold the outboard motor up?
    • N
      Natasha JamesAug 3, 2025
      If your Yamaha Outboard Motor's PTT unit isn't holding the motor up, a possible cause is that the manual valve is opened; check the manual valve. Also, there might not be enough PTT fluid, so ensure you add sufficient fluid. Another reason could be PTT fluid leakage; in this case, check the PTT unit for leakage. Finally, the main valves might not be operating, requiring you to disassemble and inspect the PTT unit.
  • C
    craig66Aug 10, 2025
    What to do if Yamaha 55DEHD Outboard Motor gear shift does not operate properly?
    • S
      Steven WilliamsonAug 10, 2025
      If the gear shift on your Yamaha Outboard Motor isn't working right, several things could be the cause. It might be a problem with the remote control box, so check and adjust that first. Also, inspect the shift cable and its end for any issues. Other potential causes include a malfunction in the shift rod operation, improper shift cam position, a faulty plunger spring, a broken cross pin, or a worn dog clutch. For these, you'll need to disassemble the lower case to check the shift rod, plunger, dog clutch, shift cam, plunger spring, and cross pin.
  • T
    Taylor GonzalezAug 17, 2025
    What to do if Yamaha 55DEHD PTT motor does not operate?
    • J
      Jeffrey KimAug 18, 2025
      If the PTT motor on your Yamaha Outboard Motor isn't working, start by checking the battery terminal for loose connections. Also, ensure the battery isn't discharged. Inspect the fuse (20A) to see if it has blown. Then, check the PTT motor lead and ground circuit for any shorts, opens, or loose connections. Finally, if none of those are the cause, you may need to disassemble and check the PTT motor itself for a malfunction.
  • A
    Adam SimpsonAug 26, 2025
    How to troubleshoot Yamaha 55DEHD PTT relay?
    • J
      Jay WilliamsAug 26, 2025
      If the PTT relay on your Yamaha Outboard Motor isn't working, it could be due to a short, open, or loose connection in the wiring harness; check the wiring harness for continuity. Another possibility is a PTT relay malfunction, so check the PTT relay itself.

Summary

General information

How to use this manual

Explains the manual's format and how to use it effectively.

Safety while working

Outlines crucial safety procedures to follow during maintenance and repair operations.

Identification

Details how to identify the outboard motor models and locate the serial number.

Special service tool

Lists and illustrates specialized tools required for servicing Yamaha outboard motors.

Propeller selection

Guides the selection of the appropriate propeller based on boat and motor performance needs.

Predelivery check

Provides a checklist for essential checks before delivering the outboard motor to ensure proper function.

Specification

General specification

Presents basic specifications for various models, including dimensions, weight, and performance data.

Maintenance specification

Details specific measurements and tolerances for engine and component maintenance.

Tightening torque

Lists specified torque values for fasteners in different parts of the motor for proper assembly.

Periodic check and adjustment

Maintenance interval chart

Provides a schedule for regular maintenance tasks based on operating hours and time intervals.

Top cowling

Instructions for checking the fit and condition of the top cowling and its related components.

Fuel system

Procedures for checking and maintaining the fuel system, including fuel joints and hoses.

Power unit

Covers checks for spark plug, thermostat, and cooling water passages in the power unit.

Control system

Details synchronization of carburetors, throttle cable adjustment, and timing checks.

Bracket

Procedures for checking PTT operation, fluid level, and tilt mechanisms.

Lower unit

Covers checks for gear oil level, gear oil change, and air leakage in the lower unit.

General

General checks including anodes, battery, and lubrication points.

Fuel system

Hose routing

Illustrates the correct routing of fuel and cooling water hoses on the engine.

Fuel line

Details the components and connections of the fuel line system.

Fuel pump

Covers the disassembly, checking, and assembly of the fuel pump.

Carburetor

Procedures for disassembling, checking, and assembling the carburetor.

Power unit

Power unit

Focuses on checking the compression pressure of the power unit.

Intake manifold

Details removal and checking procedures for the intake manifold and reed valve assembly.

Cylinder head, exhaust cover

Covers disassembly and checking of the cylinder head and exhaust cover components.

Crankcase

Details procedures for removing and disassembling the crankcase and its related parts.

Lower unit

Lower unit

Exploded view and parts list for the lower unit assembly.

Propeller shaft housing

Procedures for removing, disassembling, and checking the propeller shaft housing.

Drive shaft and lower case

Covers removal, disassembly, and assembly of the drive shaft and lower case components.

Shimming

Explains the process of shimming for proper gear and bearing alignment.

Backlash

Details how to measure and adjust gear backlash for forward and reverse gears.

Bracket unit

Tiller handle

Covers checks and assembly procedures for the tiller handle components.

Bottom cowling

Details the disassembly and assembly of the bottom cowling.

Upper case, steering arm

Procedures for disassembly, checking, and assembly of the upper case and steering arm.

Clamp bracket and swivel bracket

Covers disassembly, checking, and assembly of clamp and swivel brackets.

PTT unit

Details checking hydraulic pressure and assembly of the PTT unit.

PTT motor

Procedures for disassembling, checking, and assembling the PTT motor.

Gear pump

Covers disassembly, checking, and assembly of the gear pump.

Tilt cylinder and trim cylinder

Procedures for disassembling, checking, and assembling the tilt and trim cylinders.

PTT electrical system

Covers checks for the fuse, PTT relay, and trim sensor.

Electrical system

Checking the electrical component

Explains how to measure peak voltage of electrical components using special tools.

Electrical component

Provides a starboard view of the electrical components and their connections.

Ignition and ignition control system

Covers checks for spark plug, ignition coil, CDI unit, pulser coil, and charge coil.

Starting system

Details checks for the fuse, engine start switch, and engine stop lanyard switch.

Starter motor

Procedures for removing, checking, and installing the starter motor and its components.

Charging system

Covers checks for the lighting coil and Rectifier Regulator.

Troubleshooting

Troubleshooting the power unit

Provides a guide to diagnosing and resolving common issues with the power unit.

Troubleshooting the PTT unit

Offers solutions for problems related to the PTT unit's operation and hydraulic pressure.

Troubleshooting the lower unit

Helps diagnose and fix issues with the gear shift operation in the lower unit.

Yamaha 55DEHD Specifications

General IconGeneral
BrandYamaha
Model55DEHD
CategoryOutboard Motor
LanguageEnglish

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