Murray 7800490 Lawn Mower Manual

The Murray 7800490 is a walk-behind, self-propelled lawn mower featuring a Briggs & Stratton engine, 21-inch steel cutting deck, 3-in-1 capability (mulch, bag, side discharge), single-lever height adjustment, rear-wheel drive, and easy-start system. Designed for residential use on medium-sized lawns. 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 & Discharge Options 7. Maintenance Schedule 9. Storage Guidelines 10. Safety Information 11. Warranty & Support 12. Troubleshooting

Features at a Glance

Key components: Briggs & Stratton engine, 21-inch steel deck, rear bagger, height adjustment lever, drive control bar, fuel tank, oil dipstick, and recoil starter.

Feature	Description
Engine	Briggs & Stratton 125cc OHV engine with easy-start system
Cutting Width	21-inch steel cutting deck
Cutting Options	3-in-1: Mulch, Bag, Side Discharge
Drive System	Self-propelled rear-wheel drive
Height Adjustment	Single-lever, 6 positions (1.5" to 3.75")
Fuel Capacity	0.5 gallon (1.9 L) unleaded gasoline
Starter	Recoil (pull-start)
Wheels	8-inch rear, 7-inch front
Bag Capacity	2.0 bushels (rear bagger)
Weight	Approx. 65 lbs (29.5 kg)

Assembly Instructions

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

Handle Assembly: Attach upper and lower handle sections using provided bolts and wrench. Tighten securely.
Wheel Installation: Slide wheels onto axles; secure with hairpin clips or bolts as per model.
Bag Attachment: Connect rear bagger to deck hooks; ensure bag frame is locked in place.
Control Cables: Connect drive control cable to engine bracket; adjust for proper tension.
Side Discharge Chute: Attach if using side discharge option (mulch plug removed).

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

First-Time Setup

Before first use, complete engine preparation and safety checks.

Add Oil: Fill engine with SAE 30 detergent oil (approx. 20 oz). Check dipstick.
Add Fuel: Use fresh unleaded gasoline (87 octane min). Do not overfill.
Blade Check: Ensure cutting blade is properly installed and tightened.
Height Adjustment: Set cutting height to highest position for initial test.
Safety Check: Verify all controls move freely; bag/discharge chute properly attached.

CAUTION! Never add fuel while engine is hot or running. Work in well-ventilated area.

Specifications

Model: Murray 7800490
Engine: Briggs & Stratton 125cc, 4-cycle OHV
Cutting Width: 21 inches (53 cm)
Cutting Height: 6 positions: 1.5" to 3.75" (3.8 - 9.5 cm)
Drive: Self-propelled, rear-wheel
Deck Material: Powder-coated steel
Fuel Type: Unleaded gasoline (87 octane minimum)
Oil Type: SAE 30 detergent oil (API service class SJ or higher)
Starting System: Recoil pull-start
Warranty: 2-year limited (see warranty card)

Controls and Operation

Familiarize yourself with all controls before starting.

Handle Controls: Drive control bar (squeeze to engage drive), Height adjustment lever, Recoil starter grip.

Operation Steps:

Check oil and fuel levels.
Set cutting height via lever.
Attach bag, mulch plug, or side discharge chute as desired.
Prime engine (if equipped): Press primer bulb 3 times.
Set throttle to FAST position.
Pull recoil starter firmly.
To engage self-propelled drive: Squeeze drive control bar against handle.
To stop engine: Release drive control and move throttle to STOP.

Safety Interlock: Engine will stop if drive control is released while blade is engaged.

Cutting & Discharge Options

Configure mower for desired cutting style.

Mulching: Install mulch plug in rear discharge opening. Cuttings are recut and returned to lawn.
Bagging: Attach rear bagger. Ensure bag is empty and vents are clear.
Side Discharge: Remove mulch plug; attach side discharge chute. Use for tall/wet grass.

Tip: For best mulching, mow when grass is dry and cut no more than 1/3 of grass height.

Maintenance Schedule

Regular maintenance ensures optimal performance and longevity.

Maintenance Task	Frequency
Check engine oil level	Before each use
Check for loose fasteners	Before each use
Clean underside of deck	After each use (when cool)
Inspect/replace air filter	Every 25 hours or season
Change engine oil	First 5 hours, then every 50 hours or season
Replace spark plug	Every 100 hours or season
Sharpen/replace blade	Every 25 hours or as needed
Lubricate wheel bearings	Every season

Blade Sharpening: Disconnect spark plug wire. Remove blade; sharpen at original angle (balance after sharpening).

Storage Guidelines

Proper storage prevents fuel system issues and corrosion.

End of Season: Run engine to use up fuel or add fuel stabilizer.
Oil Change: Change oil if not done recently.
Clean: Thoroughly clean deck, wheels, and engine area.
Blade: Sharpen and coat with light oil.
Storage Location: Store in clean, dry place; cover mower.

CAUTION! Never store mower with fuel in tank indoors or near open flame.

Safety Information

Read and understand all safety instructions before operation.

Wear sturdy shoes, long pants, and eye protection.
Clear mowing area of stones, sticks, and debris.
Never mow wet grass or in poor light.
Do not allow children to operate mower.
Disconnect spark plug wire before performing maintenance.
Never remove grass bag or unclog chute while engine is running.
Use extreme caution when mowing on slopes; mow across slope, not up/down.

DANGER! Rotating blade can cause severe injury. Keep hands and feet away from deck.

Warranty & Support

Murray 7800490 is covered by a 2-year limited warranty for residential use. Proof of purchase required. Warranty does not cover normal wear, misuse, or lack of maintenance. For technical support or warranty service, contact Murray Customer Service at 1-800-800-7310 or visit www.murray.com. Have model number (7800490) and serial number ready.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine won't start	No fuel; old fuel; spark plug wire disconnected; choke/throttle setting	Add fresh fuel; check spark plug connection; set choke to START; prime engine.
Engine runs poorly	Dirty air filter; old fuel; clogged fuel line	Clean/replace air filter; drain old fuel; check fuel line.
Uneven cutting	Dull blade; uneven tire pressure; deck clogged	Sharpen/replace blade; inflate tires to 15 PSI; clean deck.
Self-propelled drive not working	Drive cable loose; drive belt worn	Adjust drive cable tension; inspect/replace drive belt.
Excessive vibration	Loose blade; bent blade; unbalanced blade	Tighten blade bolt; replace bent blade; balance blade.
Grass not discharging properly	Wet grass; deck clogged; engine speed too low	Mow when dry; clean deck; operate at FULL throttle.

For Service: Authorized service centers listed at www.murray.com. Always disconnect spark plug before any repair.