Murray 7800804 Lawn Mower Manual

The Murray 7800804 is a 21-inch push lawn mower featuring a 140cc Briggs & Stratton engine, 3-in-1 mulching/bagging/side discharge capability, single-lever height adjustment, durable steel deck, and easy-start system. This manual covers safety, assembly, operation, maintenance, troubleshooting, and specifications to ensure proper use and longevity of your mower.

1. Features at a Glance 2. Assembly Instructions 3. Safety Information 4. Specifications 5. Controls and Operation 6. Cutting Height Adjustment 7. Maintenance Schedule 8. Storage Guidelines 9. Warranty Information 10. Troubleshooting

Features at a Glance

Key components: 140cc Briggs & Stratton engine, 21-inch steel cutting deck, 3-in-1 function, single-lever height adjustment, rear bagger, mulching plug, and side discharge chute.

Feature	Description
Engine	140cc Briggs & Stratton 675 Series, 4-cycle
Cutting Width	21 inches
Cutting Deck	Durable steel construction
Cutting Options	Mulch, Bag, Side Discharge (3-in-1)
Height Adjustment	Single lever, 6 positions (1.5-3.75 inches)
Starting System	Recoil start with primer bulb
Wheels	8-inch rear, 7-inch front
Fuel Tank Capacity	0.95 quarts (0.9 liters)
Oil Capacity	20 oz (0.6 liters)
Weight	Approximately 65 lbs (29.5 kg)

Assembly Instructions

Unpack all parts and inspect for damage. 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 side discharge chute: Attach to deck opening if using side discharge.
Add engine oil: Fill with SAE 30 detergent oil (check dipstick).
Add fuel: Use fresh unleaded gasoline (87 octane minimum).

WARNING! Do not add fuel or oil indoors. Keep away from sparks or flames.

Safety Information

Read all instructions before operating. Always wear appropriate safety gear.

Clear mowing area: Remove stones, toys, and debris.
Check equipment: Ensure all parts are secure, blades are sharp and balanced.
Start safely: Firmly grip handle, pull starter cord smoothly.
Operate carefully: Mow across slopes, not up and down. Never leave mower unattended.
Stop engine: Release blade control handle, wait for blades to stop before crossing paths or adjusting.

DANGER! Keep hands and feet away from rotating blades. Do not mow wet grass.

Specifications

Model: Murray 7800804
Engine: Briggs & Stratton 675 Series, 140cc, 4-cycle
Cutting Width: 21 inches
Cutting Height: 1.5 to 3.75 inches (6 positions)
Deck Material: Steel
Wheels: 8-inch rear, 7-inch front
Fuel Type: Unleaded gasoline (87 octane minimum)
Oil Type: SAE 30 detergent oil (API service classification SJ or higher)
Dimensions (LxWxH): 54 x 22 x 42 inches (assembled)
Warranty: 2-year limited warranty

Controls and Operation

Handle Controls: Blade control handle (must be held for blades to rotate), drive control lever (if self-propelled model). Engine Controls: Throttle lever, primer bulb, choke control, recoil starter.

Starting Procedure:

Check oil and fuel levels.
Move throttle to FAST position.
Press primer bulb 3 times (cold engine).
Pull starter cord firmly until engine starts.
Allow engine to warm up 30 seconds before mowing.

Stopping: Release blade control handle, move throttle to STOP position.

Cutting Height Adjustment

Single-lever adjustment for all four wheels simultaneously.

Stop engine and wait for blades to stop completely.
Pull height adjustment lever toward wheel.
Move lever to desired position (1-6, lowest to highest).
Release lever to lock in position.
Check all wheels are at same height before mowing.

Tip: For first mow of season, set to highest position. Never remove more than 1/3 of grass height at one time.

Maintenance Schedule

Regular maintenance ensures optimal performance and extends mower life.

Maintenance Task	Frequency
Check engine oil level	Before each use
Check for loose bolts/nuts	Before each use
Clean underside of deck	After each use
Sharpen/replace blade	Every 25 hours or when dull
Change engine oil	First 5 hours, then every 50 hours
Replace air filter	Every 25 hours (more often in dusty conditions)
Replace spark plug	Every 100 hours
Check wheel bearings	Every season

CAUTION! Always disconnect spark plug wire before performing any maintenance.

Storage Guidelines

Proper storage prevents fuel system problems and corrosion.

Clean mower thoroughly, especially underside.
Drain fuel tank or add fuel stabilizer.
Run engine until it stops to clear carburetor.
Change oil if due.
Remove spark plug, add 1 tablespoon oil to cylinder, pull starter slowly to distribute.
Store in dry, covered area away from children.

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

Warranty Information

Murray 7800804 comes with 2-year limited warranty covering defects in materials and workmanship. Warranty does not cover normal wear, improper maintenance, accident, or commercial use. Proof of purchase required. For warranty service, contact authorized Murray service center or call 1-800-800-7310. Keep this manual and receipt for reference.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine won't start	No fuel, stale fuel, clogged filter	Add fresh fuel, clean/replace fuel filter, check spark plug.
Engine runs poorly	Dirty air filter, old fuel	Clean/replace air filter, drain and refill with fresh fuel.
Uneven cutting	Dull blade, uneven tire pressure	Sharpen/balance blade, check tire pressure, level deck.
Excessive vibration	Loose blade, bent blade, debris	Tighten blade bolt, replace bent blade, clean deck.
Loss of power	Clogged deck, dirty filter	Clean underside of deck, replace air filter.
Wheels not turning	Debris in wheel gears	Clean wheel axles and gears, lubricate if needed.

Service: For repairs not covered in manual, contact authorized service center at 1-800-800-7310 or visit www.murray.com.