Mercury 4.3 TKS series

Questions and Answers:

K
Kevin GrayAug 18, 2025
Why Mercury 4.3 TKS Engine starter motor will not crank or cranks slow?
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  Leslie MooreAug 18, 2025
  If the starter motor of your Mercury Engine isn't cranking or is cranking slowly, there could be several reasons. The battery switch might be off, so turn it on. The remote control may not be in neutral, so position it correctly. There might be an open circuit breaker or blown fuse, so check and reset the breaker or replace the fuse. Also, check for loose or dirty electrical connections or damaged wiring, cleaning and tightening where necessary. A bad or low battery could be the issue, so test and charge or replace it. Finally, ensure the lanyard stop switch isn't activated.
M
Madeline ShannonAug 22, 2025
What to do if Mercury 4.3 TKS has excessive temperature?
- Z
  zgoodmanAug 22, 2025
  If your Mercury Engine is overheating, first check if the water inlet or seacock is closed and open it. Inspect the drive belt for looseness or poor condition, and replace or adjust it as needed. Clear any obstructions from the seawater pickups or sea strainer. If the thermostat is faulty, replace it. For closed cooling systems, check and repair any causes of low coolant level, then fill the system with the correct coolant solution. Clean any foreign material from the heat exchanger and fluid coolers. Check for leaks in the closed cooling section and inspect the pressure cap. Repair a faulty seawater pickup pump, and clean any restrictions from the seawater discharge or exhaust elbows.
D
dixongregoryAug 26, 2025
How to fix Mercury Engine running rough, missing, or backfiring?
- S
  Shelley PhillipsAug 26, 2025
  If your Mercury Engine is running rough, missing, or backfiring, the possible causes include a clogged fuel filter (replace the filter), stale or contaminated fuel (drain the fuel tank and fill with fresh fuel), a kinked or clogged fuel line or fuel tank vent line (replace kinked lines or blow out lines with compressed air to remove the obstruction), a dirty flame arrestor (clean the flame arrestor), or a faulty ignition system component (service the ignition system).
R
Randall StevensAug 27, 2025
Why is my Mercury 4.3 TKS Engine battery will not recharge?
- J
  John MontoyaAug 28, 2025
  If your Mercury Engine's battery isn't recharging, it might be due to excessive current draw, so turn off nonessential accessories. The alternator drive belt could be loose or in poor condition, requiring replacement or adjustment. The battery itself might be in unacceptable condition, needing a test and potential replacement. Check for loose or dirty electrical connections or damaged wiring, cleaning, tightening, or repairing as necessary. Lastly, the alternator could be faulty, requiring a test and potential replacement.
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Cory WaltonAug 30, 2025
What causes poor performance in a Mercury 4.3 TKS Engine?
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  Dr. Christopher DillonAug 30, 2025
  Poor performance in your Mercury Engine can stem from several factors: the throttle not fully open (inspect the cable and linkages), a damaged or improper propeller (replace it), excessive bilge water (drain and find the entry point), an overloaded boat or improperly distributed load (reduce or redistribute the load), a dirty flame arrestor (clean it), or a fouled or damaged boat bottom (clean or repair it). Also, consider possible ignition problems.
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Andre WagnerSep 2, 2025
What to do if Mercury 4.3 TKS power trim does not operate (motor operates but sterndrive unit does not move)?
- K
  Kristi JohnsonSep 2, 2025
  If the motor operates, but the sterndrive unit on your Mercury Engine's power trim doesn't move, the trim pump oil level may be low, so fill the pump with oil. Alternatively, the drive unit might be binding in the gimbal ring, so check for obstructions.
C
Caitlyn DavidsonSep 4, 2025
What causes steering wheel to jerk or be difficult to turn on Mercury 4.3 TKS Engine?
- A
  Amber DennisSep 4, 2025
  If the steering wheel of your Mercury Engine jerks or is hard to turn, check the power steering pump fluid level and look for leaks, refilling the system if needed. Inspect the drive belt for looseness or damage, replacing or adjusting it as necessary. Ensure steering components are well-lubricated. Also, check for any loose or missing steering fasteners or parts.
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Wayne KleinSep 7, 2025
What to do if Mercury 4.3 TKS Engine power trim does not operate (motor does not operate)?
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  doylerachelSep 7, 2025
  If the motor of your Mercury Engine's power trim does not operate, start by checking for a blown fuse and replace it. Fuses may be near the dash trim switch, at the trim pump, or in the positive power trim battery lead near the battery switch. Also, inspect for loose or dirty electrical connections or damaged wiring, cleaning, tightening, or repairing as necessary.
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watersjoseSep 9, 2025
Why is Mercury 4.3 TKS Engine remote control difficult to move or makes unusual sounds?
- H
  Holly WalkerSep 9, 2025
  If the remote control on your Mercury Engine is hard to move, has excessive play, or makes unusual sounds, it could be due to insufficient lubrication on the shift and throttle linkage fasteners, so lubricate them. There might be an obstruction in the shift or throttle linkages, so remove it. Also, a shift or throttle cable could be kinked, so straighten the cable.
T
Travis WalkerSep 12, 2025
What causes low engine oil pressure in Mercury Engine?
- M
  Maria JacksonSep 12, 2025
  Low oil pressure in your Mercury Engine can be caused by insufficient oil in the crankcase, so check and add oil. It could also be due to excessive oil in the crankcase, causing aeration, so check and remove the required amount, investigating the cause of the excess. Another cause may be diluted or improper viscosity oil, so change the oil and filter, using the correct grade and viscosity, and determine the cause of the dilution.

Mercury 4.3 TKS series Specifications

General

Engine Type	4-Stroke
Recommended Fuel	87 Octane
Ignition System	CDI
Fuel Type	Gasoline
Gear Shift	F-N

Summary

Section 1 - Getting to Know Your Power Package

Identification

Locating and understanding serial number decals and stamps on the power package.

Lanyard Stop Switch

Function and operation of the safety lanyard stop switch for engine shutdown.

Instrumentation

Overview of VesselView, SmartCraft, and System Link digital instrument displays.

Remote Controls

Explanation of panel and console mount features for throttle and shift controls.

Power Trim

Adjusting sterndrive angle for optimal boat performance and trailering.

Electrical System Overload Protection

Identification and function of fuses and circuit breakers for engine protection.

Audio Warning System

Understanding and testing the engine's audible alarm system for critical faults.

Section 2 - On the Water

Safe Boating Recommendations

Guidelines for safe operation, including equipment, weather, and passenger safety.

Carbon Monoxide Exposure

Awareness of CO hazards, symptoms, and prevention measures.

Basic Boat Operation

Procedures for launching, starting, stopping, and operating the engine.

Trailering the Boat

Considerations for trailering the boat with the sterndrive unit.

High-Speed and High-Performance Operation

Recommendations for operating high-speed or high-performance boats.

Passenger Safety

Ensuring passenger safety in various boat types and conditions.

Wave and Wake Jumping

Hazards and precautions associated with wave or wake jumping.

Impact with Underwater Hazards

Reducing speed and impact damage from underwater obstacles.

Conditions Affecting Operation

Factors like weight distribution, boat bottom, cavitation, and ventilation.

Getting Started

Break-in period and post-break-in period recommendations for engine longevity.

Section 3 - Specifications

Fuel Requirements

Guidelines on gasoline types, octane ratings, and alcohol content.

Engine Oil

Recommended oil type and specifications for optimum engine performance.

Engine Specifications

Detailed technical specifications for the 4.3 TKS engine model.

Fluid Specifications

Capacities and fluid types for engine oil, cooling, and sterndrives.

Section 4 - Maintenance

OwnerOperator Responsibilities

Operator's duties for safety checks, lubrication, and maintenance.

Dealer Responsibilities

Dealer's role in predelivery inspection and customer familiarization.

Maintenance Schedule-Sterndrive Models

Routine and scheduled maintenance tasks based on time or hours.

Engine Oil

Procedures for checking, filling, and changing engine oil and filter.

Power Steering Fluid

Checking, filling, and changing power steering fluid.

Engine Coolant

Procedures for checking and filling engine coolant.

Alpha Sterndrive Gear Lube

Checking, filling, and changing gear lube for Alpha sterndrives.

Sterndrive Gear Lube

Checking, filling, and changing gear lube for sterndrives.

Power Trim Fluid

Checking, filling, and changing power trim fluid.

Cleaning the Flame Arrestor

Procedure for cleaning the flame arrestor and related components.

Positive Crankcase Ventilation (PCV) Valve

Procedure for changing the PCV valve.

Changing the WaterSeparating Fuel Filter

Procedure for replacing the water-separating fuel filter.

Lubrication

Lubrication points for steering systems and control cables.

Driveshaft Ujoint Splines and ORings

Greasing U-joint splines and O-rings on the sterndrive unit.

Propellers

Information on propeller repair and removal/installation.

Serpentine Drive Belt

Checking belt tension and condition, and replacing the belt.

Flushing the Power Package

Procedures for flushing the Alpha and Bravo power packages.

Sterndrive Corrosion Protection Components

Identifying and understanding sterndrive corrosion protection devices.

MerCathode System Battery Requirements

Battery charge requirements for the MerCathode system.

Section 5 - Storage

Cold Weather or Extended Storage

Guidelines for storing the boat during cold weather or extended periods.

Preparing Power Package for Storage-Carburetor Models

Detailed steps for engine and fuel system preparation for storage.

Draining the Seawater System

Procedures for draining seawater cooling systems to prevent freeze damage.

Air Actuated Single-Point Drain System

Procedure for draining the cooling system using an air pump.

Manual Single-Point Drain System (Alpha)

Draining procedures for Alpha models with manual drain systems.

Three-Point Manual Drain System-Seawater Cooled

Draining procedures for three-point manual systems in seawater cooled engines.

Draining Water from the Gen III Cool Fuel Module

Procedure for draining water from the Gen III Cool Fuel Module.

Draining the Sterndrive

Procedure for draining the sterndrive for storage or specific water conditions.

Battery Storage

Recommendations for storing batteries during extended periods.

Recommissioning the Power Package

Steps to prepare the power package after storage.

Section 6 - Troubleshooting

Starter Motor Will Not Crank Engine, or Cranks Slow

Diagnosing and resolving issues with the starter motor.

Engine Will Not Start or Is Hard to Start

Troubleshooting steps for engines that fail to start or start with difficulty.

Engine Runs Rough, Misses, or Backfires

Identifying causes and solutions for rough engine operation.

Poor Performance

Diagnosing and rectifying issues leading to reduced engine performance.

Excessive Engine Temperature

Troubleshooting engine overheating issues.

Insufficient Engine Temperature

Diagnosing and resolving issues related to low engine operating temperature.

Low Engine Oil Pressure

Troubleshooting causes of low engine oil pressure.

Battery Will Not Recharge

Diagnosing problems with battery charging and performance.

Remote Control Is Difficult to Move, Has Excessive Play, or Makes Unusual Sounds

Troubleshooting remote control operation issues.

Steering Wheel Jerks or Is Difficult to Turn

Diagnosing and resolving steering system problems.

Power Trim Does Not Operate

Troubleshooting power trim system failures (motor not operating).

Power Trim Does Not Operate (Motor Operates but Sterndrive Unit Does Not Move)

Troubleshooting power trim issues where the motor runs but the unit doesn't move.

Section 7 - Customer Assistance Information

Owner Service Assistance

Guidance on obtaining service, including local and remote dealer information.

Replacement Service Parts

Information on selecting and using correct replacement parts.

Parts and Accessories Inquiries

How to inquire about or order Quicksilver parts and accessories.

Resolving a Problem

Steps to take if you encounter issues or have questions about your product.

Contact Information for Mercury Marine Customer Service

Contact details for Mercury Marine customer support by region.

Customer Service Literature

Information on obtaining manuals and other product literature.

Section 8 - Checklists

Predelivery Inspection (PDI)

Checklist for tasks to perform before customer delivery of the power package.

Customer Delivery Inspection (CDI)

Checklist for final inspection and customer orientation.

Section 9 - Maintenance Log

Scheduled Maintenance Log

Log for recording scheduled maintenance based on hours of operation.

Vessel Maintenance Notes

Space to record general maintenance performed and save receipts.

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Mercury 4.3 TKS series

Table of Contents

Questions and Answers:

Mercury 4.3 TKS series Specifications

Summary

Section 1 - Getting to Know Your Power Package

Identification

Lanyard Stop Switch

Instrumentation

Remote Controls

Power Trim

Electrical System Overload Protection

Audio Warning System

Section 2 - On the Water

Safe Boating Recommendations

Carbon Monoxide Exposure

Basic Boat Operation

Trailering the Boat

High-Speed and High-Performance Operation

Passenger Safety

Wave and Wake Jumping

Impact with Underwater Hazards

Conditions Affecting Operation

Getting Started

Section 3 - Specifications

Fuel Requirements

Engine Oil

Engine Specifications

Fluid Specifications

Section 4 - Maintenance

OwnerOperator Responsibilities

Dealer Responsibilities

Maintenance Schedule-Sterndrive Models

Engine Oil

Power Steering Fluid

Engine Coolant

Alpha Sterndrive Gear Lube

Sterndrive Gear Lube

Power Trim Fluid

Cleaning the Flame Arrestor

Positive Crankcase Ventilation (PCV) Valve

Changing the WaterSeparating Fuel Filter

Lubrication

Driveshaft Ujoint Splines and ORings

Propellers

Serpentine Drive Belt

Flushing the Power Package

Sterndrive Corrosion Protection Components

MerCathode System Battery Requirements

Section 5 - Storage

Cold Weather or Extended Storage

Preparing Power Package for Storage-Carburetor Models

Draining the Seawater System

Air Actuated Single-Point Drain System

Manual Single-Point Drain System (Alpha)

Three-Point Manual Drain System-Seawater Cooled

Draining Water from the Gen III Cool Fuel Module

Draining the Sterndrive

Battery Storage

Recommissioning the Power Package

Section 6 - Troubleshooting

Starter Motor Will Not Crank Engine, or Cranks Slow

Engine Will Not Start or Is Hard to Start

Engine Runs Rough, Misses, or Backfires

Poor Performance

Excessive Engine Temperature

Insufficient Engine Temperature

Low Engine Oil Pressure

Battery Will Not Recharge

Remote Control Is Difficult to Move, Has Excessive Play, or Makes Unusual Sounds

Steering Wheel Jerks or Is Difficult to Turn

Power Trim Does Not Operate

Power Trim Does Not Operate (Motor Operates but Sterndrive Unit Does Not Move)

Section 7 - Customer Assistance Information

Owner Service Assistance

Replacement Service Parts

Parts and Accessories Inquiries

Resolving a Problem

Contact Information for Mercury Marine Customer Service

Customer Service Literature