Murray 425603x99A Lawn Mower Manual

The Murray 425603x99A is a 21-inch push lawn mower featuring a 159cc Briggs & Stratton engine, 3-in-1 mulching/bagging/side discharge capability, single-lever height adjustment (6 positions), durable steel deck, easy-start system, and rear-wheel drive. Below are key sections for safety, features, assembly, operation, maintenance, and troubleshooting.

1. Features at a Glance 2. Assembly Instructions 3. First-Time Setup 4. Specifications 5. Controls and Operation 6. Cutting Height Adjustment 7. Mulching & Bagging 8. Safety Features 9. Maintenance Schedule 10. Warranty Information 11. Troubleshooting

Features at a Glance

Key components: 159cc Briggs & Stratton engine, 21-inch steel cutting deck, rear bagger, mulching plug, height adjustment lever, drive control bar, safety key.

Feature	Description
Engine	159cc Briggs & Stratton 450E series, OHV
Cutting Width	21 inches
Cutting Height	6 positions (1.5-3.75 inches)
Deck Material	Powder-coated steel
Drive System	Rear-wheel drive with drive control bar
Capability	3-in-1 (Mulch, Bag, Side Discharge)
Wheels	8-inch rear, 7-inch front
Starter	Recoil with Easy-Spin™ technology
Fuel Tank	1.1-quart capacity
Safety Features	Blade brake clutch, safety key, operator presence control

Assembly Instructions

Unpack and inspect all parts. Assembly requires basic tools (included).

Attach handle: Align lower handle with deck brackets, secure with bolts and wing nuts.
Install upper handle: Connect to lower handle, secure with provided hardware.
Attach grass bag: Hook bag frame onto rear deck brackets; ensure secure fit.
Install mulching plug: Insert into rear discharge chute when mulching.
Add oil and fuel: Use SAE 30 detergent oil (20 oz); fill with unleaded gasoline.

WARNING! Always wear gloves during assembly. Ensure all fasteners are tight before operation.

First-Time Setup

Before first use, complete pre-operation checks.

Check oil level: Ensure oil is at full mark on dipstick.
Add fuel: Use fresh unleaded gasoline (87 octane minimum).
Inspect blade: Ensure blade is sharp and securely fastened.
Adjust cutting height: Set lever to desired position (middle setting recommended).
Test safety features: Verify blade brake clutch stops blade within 3 seconds when handle is released.

CAUTION! Never operate without oil or with dull/damaged blade. Keep hands and feet away from discharge area.

Specifications

Model: Murray 425603x99A
Engine: Briggs & Stratton 450E series, 159cc, OHV
Cutting Width: 21 inches
Cutting Height Range: 1.5 - 3.75 inches (6 positions)
Deck: 21-inch steel, powder-coated
Drive: Rear-wheel drive
Wheels: 8-inch rear, 7-inch front
Fuel Capacity: 1.1 quarts
Oil Capacity: 20 oz (SAE 30 detergent)
Weight: 65 lbs (approx.)
Warranty: 2-year limited

Controls and Operation

Main controls located on handle. Engine controls on engine housing.

Handle Controls: Drive control bar (squeeze to engage drive), height adjustment lever, bagger release lever.

Engine Controls: Throttle control (CHOKE/RUN/FAST/SLOW), primer bulb, recoil starter, ignition key.

Starting Procedure: Insert safety key, set throttle to CHOKE (cold) or FAST (warm), press primer 3 times, pull recoil starter. Allow 30-second warm-up.

Stopping: Release drive bar, move throttle to STOP, remove safety key.

Cutting Height Adjustment

Single-lever adjustment for all four wheels.

Stop engine and wait for blade to stop completely.
Pull height adjustment lever outward.
Move lever to desired position (1=lowest, 6=highest).
Release lever to lock position.
Verify all wheels are at same height.

Tip: For first mow of season, set to highest position. Never adjust height while engine is running.

Mulching & Bagging

3-in-1 system: mulch, bag, or side discharge.

Mulching: Install mulching plug in rear discharge chute. Ensure grass bag is removed. Best for dry grass ≤3 inches.
Bagging: Remove mulching plug, attach grass bag. Empty bag when ¾ full.
Side Discharge: Remove both mulching plug and grass bag. Use for tall/wet grass.

WARNING! Always stop engine before changing cutting mode. Keep hands clear of discharge chute.

Safety Features

Blade Brake Clutch: Stops blade within 3 seconds when handle is released. Operator Presence Control: Engine stops if operator leaves position. Safety Key: Must be inserted to start engine. Shielded Discharge: Redirects clippings downward.

Maintenance Schedule

Regular maintenance ensures optimal performance and longevity.

Interval	Task
Before each use	Check oil level, inspect blade, clear deck of debris
Every 25 hours	Change oil, clean/replace air filter, check spark plug
Every season	Sharpen/replace blade, lubricate wheels, clean underside
Storage	Drain fuel or add stabilizer, clean thoroughly, store indoors

CAUTION! Disconnect spark plug wire before performing any maintenance.

Warranty Information

Murray 425603x99A includes 2-year limited warranty covering defects in materials/workmanship. Warranty does not cover normal wear, misuse, or lack of maintenance. For warranty service, contact Murray customer service at 1-800-800-7310 or visit www.murray.com. Keep original receipt as proof of purchase.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine won't start	No fuel, old gas, clogged filter	Add fresh fuel, check fuel line, clean/replace air filter.
Engine runs poorly	Dirty spark plug, old oil	Clean/replace spark plug, change oil.
Uneven cutting	Dull blade, uneven height	Sharpen/replace blade, adjust cutting height evenly.
Loss of power	Clogged deck, dirty filter	Clean underside of deck, replace air filter.
Wheels not driving	Drive cable loose	Adjust drive cable tension per manual.
Excessive vibration	Loose blade, bent spindle	Tighten blade bolt, inspect spindle for damage.

Service: For technical support: 1-800-800-7310, www.murray.com