Mercury 300 - PRO MAX 3.0L - User Manual

300 - PRO MAX 3.0L
1999 Mercury Marine 90Ć849233000 499
for your purchase of one of the finest outboards available.
You have made a sound investment in boating pleasure.
Your outboard has been manufactured by Mercury Rac-
ing, a unit of Mercury Marine, the world leader in marine
technology and outboard manufacturing since 1939.
These years of experience have been committed to the
goal of producing the finest quality products. This has led
to Mercury Racing’s reputation for strict quality control,
excellence, durability, lasting performance and being the
best at providing after-the-sale support.
Please read this manual carefully before operating your
outboard. This manual has been prepared to assist you
in the operation, safe use and care of your outboard.
All of us at Mercury Racing took pride in building your out-
board and wish you many years of happy and safe boat-
ing.
Again, thank you for your confidence in Mercury Marine.
Mercury Racing
N7480 County Road “UU”
Fond du Lac, WI 54935-9585

Mercury 300 - PRO MAX 3.0L Specifications

General

Horsepower	300 HP
Displacement	3.0L
Fuel Type	Gasoline
Cooling System	Water-cooled with thermostat
Displacement (CID)	183 CID
Fuel Induction System	Electronic Fuel Injection (EFI)
Steering	Hydraulic
Gear Ratio	1.75:1
Engine Type	V6
Alternator Output	85 Amps
Starting System	Electric Start
Shaft Length	20 in, 25 in
Ignition System	SmartCraft PCM 112 Digital Inductive

Summary

General Information

Boaters Responsibilities

Driver's duty for safe boat operation and occupant safety.

Before Operating Your Outboard

Read manual, understand safety alerts for safe operation and product protection.

Boat Horsepower Capacity

Do not overpower or overload boat. Check capacity plate for max load.

High-Speed And High-Performance Boat Operation

Seek orientation if unfamiliar with high-performance operation. Consult booklet.

Lanyard Stop Switch

Device to stop engine if operator falls out. Connect both ends.

Protecting People In The Water

Exercise caution with people in water. Shift to neutral and shut off engine.

Carbon Monoxide Risk

Avoid running engine with poor ventilation. CO is odorless and deadly.

Wave And Wake Jumping

Hazards of jumping waves/wakes. Instruct occupants to get low and hang on.

Impact With Underwater Hazards

Reduce speed in shallow/obstacle areas. Control boat speed to avoid injury/damage.

Selecting Accessories For Your Outboard

Use genuine Mercury accessories. Check compatibility and read manuals.

Safe Boating Suggestions

Familiarize with regulations, use life jackets, don't overload, perform checks.

Recording Serial Number

Record engine serial number, model year, etc. for future reference.

Specifications

Technical details of the outboard, including horsepower, weight, dimensions, etc.

Component Identification

Identifies key external and internal parts of the outboard with numbered diagrams.

Propeller Selection

How to select a propeller for optimal performance and RPM range.

Transporting

Trailering Boat;Outboard

Proper procedures for trailering a boat with an outboard attached.

Fuel & Oil

Gasoline Recommendations

Guidelines for using unleaded gasoline, octane ratings, and additives.

Oil Recommendation

Specifies the type of 2-cycle TC-W3 outboard oil to use.

Filling Fuel Tank

Safe procedures for filling the fuel tank, including precautions against fire.

Filling Remote Oil Tank

Instructions for filling the remote oil tank for the oil injection system.

Filling Engine Mounted Oil Reservoir Tank

Instructions for filling the engine-mounted oil reservoir.

Features & Controls

Remote Control Features

Identifies and explains components of the remote control system.

Warning Horn System

Explains the warning horn and its triggers for system alerts.

Engine Overheat Warning

How the overheat warning system functions and steps to take.

Engine Over-Speed Protection

System activates when engine exceeds max RPM, reducing speed.

Electrical Sensor Not Functioning

Warning activated if engine sensor fails or is out of range.

Water Separating Fuel Filter Warning

Warning when water in fuel filter reaches full level. Refer to Maintenance.

Power Trim And Tilt

How to adjust outboard position using the trim switch.

Power Trim Operation

Effects of trimming outboard in/out for performance and control.

Tilting Operation (Fleet Master;Torque Master)

Procedures for tilting outboard using tilt support lever.

Tilting Operation (Sport Master)

Procedures for tilting outboard using tilt support lever for Sport Master.

Manual Tilting

How to manually tilt the outboard if power trim fails.

Manual Tilting (Sportmaster)

Manual tilting procedures for Sportmaster models.

Operation

Engine Break-in

Procedures and guidelines for breaking in a new outboard engine.

Pre-Starting Check List

Essential checks to perform before starting the outboard.

Operating In Freezing Temperatures

How to operate and store the outboard in freezing conditions.

Operating In Salt Water Or Polluted Water

Maintenance and operational tips for saltwater use.

Operating At High Elevations

How engine performance is affected by high elevations.

Setting Trim Angle at Idle Speed

Proper trim angle at idle to avoid exhaust restriction.

Operating in Shallow Water

How to operate in shallow water to avoid hitting bottom.

Starting The Engine

Step-by-step guide to starting the outboard engine safely.

Gear Shifting

Proper procedure for shifting gears (Forward, Neutral, Reverse).

Stopping The Engine

How to safely stop the outboard engine.

Emergency Starting

Procedure for starting the engine manually if the starter system fails.

Maintenance

Outboard Care

General advice for keeping the outboard in optimal operating condition.

Inspection And Maintenance Schedule

Schedule of inspections and maintenance tasks based on usage hours.

Flushing the Cooling System (Cowl Attachment)

How to flush the cooling system using the cowl attachment.

Flushing the Cooling System (Gear Case Attachment)

How to flush the cooling system using gear case attachments.

Top Cowl Removal and Installation

Steps for removing and reinstalling the top engine cowl.

Flywheel Cover Removal and Installation

Procedures for removing and installing the flywheel cover.

Fuel System

General instructions and warnings for servicing the fuel system.

Water Separating Fuel Filter

How to remove and replace the water separating fuel filter.

Steering Link Rod Fasteners

Installation instructions and warnings for steering link rod fasteners.

Fuse Replacement

Procedure for replacing blown fuses in the electric starting circuit.

Corrosion Control Anodes

Importance and inspection of corrosion control anodes.

Propeller Replacement

Steps for safely removing and replacing the outboard propeller.

Spark Plug Inspection

How to inspect, clean, and gap spark plugs.

Battery Inspection

Safety and maintenance procedures for inspecting the boat battery.

Alternator Drive Belt Tension Adjustment

How to check and adjust the tension of the alternator drive belt.

Lubrication Points

Identifies and describes key lubrication points on the outboard.

Checking Power Trim Fluid

How to check the fluid level in the power trim system.

Gear Case Lubricant

Procedures for checking and refilling the gear case lubricant.

Storage

Storage Preparation

Procedures to prepare the outboard for out-of-season or prolonged storage.

Fuel System Preparation for Storage

How to prepare the fuel system for storage to prevent issues.

Protecting Internal Engine Components

Steps to protect internal engine components during storage.

Protecting External Outboard Components

Lubricating and protecting external parts during storage.

Gear Case Storage

Procedures for storing the gear case.

Battery Storage

Instructions for proper storage and maintenance of the battery.

Troubleshooting

Starter Motor Will Not Crank

Possible causes and solutions when the starter motor fails to crank the engine.

Engine Will Not Start

Possible causes and solutions when the engine fails to start.

Engine Runs Erratically

Causes and solutions for erratic engine performance.

Performance Loss

Possible causes for reduced engine performance.

Battery Will Not Hold Charge

Causes and solutions when the battery fails to hold a charge.

Engine Overheating

Causes and solutions for engine overheating issues.

Engine Wiring Diagram

Maintenance Log