Craftsman M310 Lawn Mower Manual

The Craftsman M310 is a 21-inch self-propelled gas lawn mower featuring a 163cc Briggs & Stratton engine, 3-in-1 mulching/bagging/side discharge capability, single-lever height adjustment (6 positions), 2-gallon fuel tank, and rear-wheel drive. This manual covers safety, assembly, operation, maintenance, troubleshooting, and specifications. Always read and follow all safety instructions before use.

1. Features at a Glance 2. Assembly Instructions 3. Safety Precautions 4. Specifications 5. Controls and Operation 6. Starting & Stopping 7. Cutting Height Adjustment 8. Maintenance Schedule 9. Storage & Winterization 10. Warranty Information 11. Troubleshooting

Features at a Glance

Key components: 21-inch steel deck, Briggs & Stratton 163cc engine, rear bagger, mulching plug, side discharge chute, single-lever height adjuster, drive control lever, and fuel tank.

Feature	Description
Engine	Briggs & Stratton 163cc OHV engine
Cutting Width	21 inches
Cutting Options	3-in-1: Mulch, Bag, Side Discharge
Drive System	Rear-wheel self-propelled
Height Adjustment	Single lever, 6 positions (1.5" to 3.75")
Fuel Tank	2-gallon capacity
Starter	Recoil pull start
Wheels	8-inch rear, 7-inch front
Deck Material	Powder-coated steel
Weight	Approx. 75 lbs (assembled)

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, tighten knobs.
Attach grass bag: Hook bag frame onto rear deck brackets; ensure secure fit.
Install mulching plug (if using): Insert into rear discharge opening.
Add oil and gasoline: Fill engine with SAE 30 oil (check dipstick); add unleaded gasoline to fuel tank.

WARNING! Do not add gasoline indoors or near ignition sources. Assemble on a flat, stable surface.

Safety Precautions

Always follow these safety rules to prevent injury or damage.

Read manual thoroughly before operation.
Clear mowing area of stones, sticks, and debris.
Wear sturdy shoes, eye protection, and long pants.
Do not mow wet grass or in poor visibility.
Keep hands and feet away from moving parts.
Turn off engine and remove spark plug wire before maintenance.
Never allow children to operate mower.
Use only outdoors in well-ventilated areas.

CAUTION! Gasoline is flammable; store in approved container away from heat.

Specifications

Model: Craftsman M310
Engine: Briggs & Stratton 163cc, 4-cycle, OHV
Cutting Width: 21 inches
Cutting Height Range: 1.5" to 3.75" (6 positions)
Drive: Rear-wheel self-propelled
Fuel Capacity: 2 gallons (unleaded gasoline)
Oil Type: SAE 30 (20 oz. capacity)
Deck Material: Powder-coated steel
Warranty: 2-year limited warranty
Weight: 75 lbs (approx.)

Controls and Operation

Main controls located on handle. Front Panel: Throttle control, drive control lever, height adjustment lever.

Handle Controls: Drive control lever (squeeze to engage drive), throttle control (FAST/SLOW/STOP), recoil starter grip, bag indicator.

Operation: Set cutting height, start engine, engage drive lever to move forward. Release drive lever to stop movement. Adjust throttle to FAST for cutting, SLOW for idling.

Starting & Stopping

Starting procedure for cold and warm engines.

Check oil and fuel levels.
Move throttle to FAST position.
Prime engine (press primer bulb 3 times for cold start).
Pull recoil starter grip firmly until engine starts.
Allow engine to warm up 30 seconds.
To stop: Move throttle to STOP position.

Tip: If engine does not start, check spark plug, fuel, and air filter.

Cutting Height Adjustment

Single lever adjusts all four wheels simultaneously.

Stop engine and ensure blades are not moving.
Pull height adjustment lever toward wheel.
Move lever to desired position (1-6, where 1 is lowest).
Release lever to lock in place.
Test mower on flat surface to ensure even cut.

WARNING! Always stop engine before adjusting cutting height.

Maintenance Schedule

Regular maintenance ensures optimal performance and longevity.

Maintenance Task	Frequency
Check oil level	Before each use
Check air filter	Every 25 hours
Replace spark plug	Every season or 100 hours
Sharpen/replace blade	Every 25 hours or as needed
Change oil	First 5 hours, then every 50 hours
Clean under deck	After each use
Check drive belt	Every 50 hours
Lubricate wheels	Every season

Storage & Winterization

Proper storage prevents fuel system damage and corrosion.

Run engine to burn remaining fuel in carburetor, or add fuel stabilizer.
Change oil and replace spark plug.
Clean deck thoroughly; remove grass clippings.
Store in dry, covered area away from moisture.
Cover mower to prevent dust accumulation.

CAUTION! Never store mower with gasoline in tank for more than 30 days without stabilizer.

Warranty Information

Craftsman M310 includes a 2-year limited warranty covering defects in materials and workmanship. Warranty does not cover normal wear, misuse, or lack of maintenance. For warranty service, contact Craftsman Customer Support at 1-888-331-4569 or visit www.craftsman.com. Keep original receipt as proof of purchase.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Engine won't start	No fuel, old gasoline, clogged air filter	Add fresh gasoline; clean/replace air filter; check spark plug.
Poor cutting performance	Dull blade, low engine speed	Sharpen or replace blade; set throttle to FAST.
Uneven cut	Uneven tire pressure, worn blade	Check tire pressure; balance or replace blade.
Mower vibrates excessively	Loose blade, debris under deck	Tighten blade bolt; clean deck interior.
Self-propel not working	Drive belt loose or worn	Adjust or replace drive belt.
Engine smokes	Overfilled oil, dirty air filter	Drain excess oil; clean air filter.

Service: For repairs, contact authorized Craftsman service center. Do not attempt major repairs if unqualified.

Support: 1-888-331-4569; www.craftsman.com