STIHL 031AV Service Manual PDF

The STIHL 031AV is a professional-grade gasoline-powered chainsaw featuring a robust engine, anti-vibration system (AV), and manual oiling. This service manual provides comprehensive instructions for maintenance, troubleshooting, repair, and safety procedures. Below are key sections covering specifications, safety, maintenance schedules, engine service, fuel system, ignition, carburetor adjustment, chain and bar maintenance, troubleshooting, and parts diagrams.

1. Features & Specifications 2. Safety Information 3. Maintenance Schedule 4. Engine Service 5. Fuel System 6. Ignition System 7. Carburetor Adjustment 8. Chain & Bar Maintenance 9. Troubleshooting 10. Parts Diagrams 11. Warranty & Support

Features & Specifications

Key components: Engine, Anti-Vibration System, Manual Oiling Pump, Chain Brake, Decompression Valve.

FeatureDescription
Engine Type2-stroke, single cylinder, air-cooled
Displacement49.4 cc (3.0 cu. in.)
Power Output2.5 kW (3.4 hp)
Fuel Tank Capacity0.55 L (18.6 fl. oz.)
Oil Tank Capacity0.26 L (8.8 fl. oz.)
Guide Bar Lengths40 cm (16") to 50 cm (20")
Chain Pitch3/8" or .325"
Weight (without bar/chain)5.9 kg (13.0 lbs)
Ignition SystemElectronic (breakerless)
Anti-VibrationSpring-mounted handles

Safety Information

Read and understand all safety warnings before operation or service.

  1. Personal Protective Equipment: Always wear safety glasses, hearing protection, gloves, chainsaw chaps, and sturdy boots.
  2. Work Area Safety: Keep bystanders and pets at least 15 feet away. Ensure secure footing.
  3. Chain Brake: Test before each use. Engage when carrying or starting.
  4. Fuel Safety: Mix fuel outdoors. Use STIHL 2-stroke oil and fresh gasoline (min. 89 octane). Store in approved container.

WARNING! A chainsaw is a dangerous tool. Failure to follow safety instructions can result in serious injury or death.

Maintenance Schedule

Regular maintenance ensures optimal performance and longevity.

  1. Before Each Use: Check chain tension, sharpness, and lubrication. Inspect for loose fasteners. Test chain brake and throttle lock.
  2. Daily (or after 5 hours): Clean air filter. Check spark plug condition.
  3. Weekly (or after 20 hours): Clean cooling fins and cylinder area. Clean spark arrestor screen (if equipped).
  4. Monthly (or after 100 hours): Clean fuel filter. Check fuel lines for cracks. Inspect anti-vibration elements.
  5. Annually: Replace fuel filter. Clean carburetor (if necessary). Check clutch and sprocket wear.

CAUTION! Allow engine to cool completely before performing maintenance.

Engine Service

Fuel System

Components: Fuel tank, cap, filter, lines, carburetor.

Fuel Line Replacement: Drain tank. Remove old lines. Install new lines with correct routing to carburetor and primer bulb (if equipped).

Fuel Filter: Replace annually or if clogged. Use STIHL part #0000 350 3501.

Fuel Mix Ratio: 50:1 (2% oil). Use 2.6 oz. of STIHL 2-stroke oil per 1 gallon of gasoline.

Ignition System

Electronic ignition module, spark plug, stop switch, wiring.

  1. Spark Plug: Type Bosch WSR6F or equivalent. Gap: 0.5 mm (0.020"). Replace if electrodes are worn or fouled.
  2. Ignition Module: Test with multimeter. Resistance between spark plug lead and ground should be 3-6 kΩ.
  3. Stop Switch: Ensure wire is connected and switch functions (continuity when pressed).

Tip: Always disconnect spark plug wire before servicing to prevent accidental starting.

Carburetor Adjustment

STIHL carburetor with H (high), L (low), and LA (idle) adjustment screws.

  1. Initial Settings: Turn H and L screws clockwise until lightly seated, then back out 1 turn each.
  2. Idle Adjustment: Start engine. Turn LA screw to achieve smooth idle (chain should not rotate).
  3. Low Speed (L): Accelerate from idle. Adjust L for smooth transition without hesitation.
  4. High Speed (H): With chain brake engaged, run at full throttle briefly. Adjust H for peak RPM (consult tachometer: approx. 12,500 RPM no-load).
  5. Final Idle: Re-check and adjust LA if necessary after H/L settings.

WARNING! Improper adjustment can cause engine damage. Final H setting may require a tachometer.

Chain & Bar Maintenance

Chain Sharpening: Use round file matching chain pitch (e.g., 4.0 mm for 3/8" chain). Maintain 30° filing angle. Keep all cutters equal length.

Bar Maintenance: Clean bar groove. Flip bar regularly for even wear. Dress rails with flat file if burred.

Chain Tension: Correct when cool – snug against bar but pullable by hand. Re-tighten after initial use.

Lubrication: Use STIHL chain oil. Check oiler output. Clean oil holes in bar.

Troubleshooting

SymptomPossible CauseCorrective Action
Engine won't startNo spark, flooded, fuel issueCheck spark plug, ignition wire. Use cold start procedure. Check fuel lines/filter.
Engine starts then diesClogged fuel filter, carburetor adjustmentReplace fuel filter. Clean carburetor. Adjust L screw.
Lacks power at full throttleClogged air filter, muffler screen, H adjustmentClean/replace air filter. Clean spark arrestor. Adjust H screw.
Chain does not oilEmpty oil tank, clogged oiler holeFill oil tank. Clean oil passage in bar and saw.
Excessive vibrationLoose fasteners, worn AV buffersTighten all nuts/bolts. Inspect and replace anti-vibration elements.

Reset: For electronic issues, disconnect spark plug wire for 1 minute to reset module.

Parts Diagrams

Refer to official STIHL 031AV IPL (Illustrated Parts List) for exploded views and part numbers.

Order genuine STIHL parts from authorized dealers.

Warranty & Support

STIHL Limited Warranty: Covers defects in materials/workmanship for specified period (see dealer for details). Proof of purchase required.

For technical support, parts, or service manuals:

STIHL USA: 1-800-467-8445 | www.stihlusa.com

Copyright: This service manual is for reference only. STIHL is a registered trademark. All specifications subject to change.

STIHL 031AV Service Manual PDF © - All Rights Reserved 2025