Why Chainsaws Won’t Start After Running? (Explained)

Operating a chainsaw can be extremely useful for tasks like tree removal, brush clearing, logging, and more. However, it can also be frustrating when your chainsaw stops running unexpectedly. Troubleshooting a chainsaw that won’t restart requires methodically checking different systems and components to isolate the issue.

With some basic mechanical knowledge and the correct tools, many problems that prevent restarting are fixable with simple adjustments or part replacements. Taking preventive maintenance steps can also reduce downtime and extend your chainsaw’s operating life.

This guide will overview the most common issues that stop a hot chainsaw from restarting. It also includes suggested solutions, maintenance tips, and a FAQ. Whether you’re a beginner or advanced user, these actionable steps will help you get your chainsaw running again.

Common Issues When Restarting a Hot Chainsaw

There are a few key reasons a previously-running chainsaw may fail to start up again after stopping. The most common culprits include:

Flooded Engine

A flooded engine prevents restarting because excess fuel in the combustion chamber blocks spark plug ignition. This over-rich air-fuel mixture occurs if the choke stays on too long after starting. It can also happen from pulling the cord too many times during a cold start attempt.Signs of a flooded engine include:

  • The chainsaw starts then dies soon after
  • It emits a wet, gurgling sound
  • Blue smoke from the exhaust
  • Gas leaking from the carburetor
  • Spark plug covered in liquid fuel

Overheated Engine

Running a chainsaw for extended periods can cause overheating. This expands components to the point where they seize and stop turning. Without rotation, the pull cord will not start the motor.Clues that overheating caused the no-restart include:

  • Chainsaw was running fine for a while then quit suddenly
  • Won’t turn over with the starter cord
  • Hot smell from engine
  • Bar and chain are very hot

Faulty Ignition System

The ignition system provides electric spark to the spark plug for combustion. Issues like broken spark plug wires, bad plugs, or faulty magnetos can cut off that connection. Without spark, fuel won’t ignite in the cylinder to power the crank and start the engine.Problems with ignition parts show these indications:

  • Has spark initially but none after stopping
  • Runs erratically or intermittently dies
  • Won’t start without starting fluid sprayed into cylinder

Carburetor Problems

The carburetor mixes air and fuel for engine combustion. Internal debris or improperly adjusted carb settings affect that process and lead to restart difficulties.Clues pointing to a faulty carburetor include:

  • Won’t start without choke on
  • Starts but stalls without throttle applied
  • Dies at high speeds or under load
  • Runs rough, sputters, or backfires

Low Compression

If an engine can’t achieve sufficient compression to reach the ignition temperature of the fuel mixture, it won’t have combustion and restart. This loss of cylinder pressure happens because of leaks around valves, piston rings, or gaskets.Signals of low compression:

  • Pull cord recoils slowly/easily
  • Doesn’t start after a few hard pulls
  • Runs rough or lacks power

Solutions for a Chainsaw That Won’t Restart

When your chainsaw suddenly stalls and won’t turn back on, there are organized ways to pinpoint the cause. By methodically verifying different systems, you can isolate the specific issue for repair.General things to check when troubleshooting problems restarting include:

  • Fuel: Empty, old, contaminated, incorrect oil mix ratio
  • Compression: Loose spark plug, damaged cylinder/rings/gaskets
  • Air Filter: Dirty, blocked intake system
  • Carburetor: Dirty jets/ports, stuck needle valve, bad gaskets/diaphragms
  • Ignition: Faulty stop switch, spark plug, magneto
  • Overheating: Clogged cooling fins/intake, seized internal parts

Refer to your operator’s manual for the manufacturer recommended inspection and maintenance procedures.Here are solutions to common issues that prevent restarting after running:

Fixing a Flooded Engine

Trying to start a flooded engine will be an exercise in futility. But the fix is usually simple:

  1. Remove spark plug: Unscrew and take out the spark plug. This helps release excess fuel from the cylinder.
  2. Dry the plug: Clean off fuel fouling on the spark plug electrode using a wire brush.
  3. Crank the engine: Pull the cord 5-6 times with the spark plug still out. This will clear excess fuel from the combustion chamber.
  4. Replace spark plug: Screw the spark plug back in, reconnect the wire. Make sure there’s a 0.5 mm gap between the electrodes.
  5. Try starting procedure: Ensure the choke is OFF/OPEN. Pull the starter cord firmly without throttle. The engine should fire up without flooding again.

Note: This process may need repeating 1-2 times in severe flooding cases before it starts. Make sure to dry the spark plug thoroughly between attempts.

Fixing an Overheated Engine

An overheated engine that seizes and won’t rotate needs to cool completely before attempting restart. This allows components like the piston and bearings to retract back to normal clearances.Let the chainsaw sit for at least 30 minutes before taking these steps:

  1. Add bar/chain oil: Check chain oil tank and refill as needed so lubrication restores during restart attempts.
  2. Loosen spark plug: Unscrew spark plug 1/2 turn. This reduces compression for easier starting.
  3. Pull starter cord: It should rotate more freely as parts cool to normal dimensions.
  4. Retighten spark plug: If cord pulls smoothly, the engine has cooled adequately. Fully tighten spark plug.
  5. Start chainsaw: Use normal starting procedure. Let it idle for several minutes to ensure proper lubrication.

Caution: If the pull cord won’t turn after cooling, this indicates a seized internal part. Continuing restart attempts risks significant engine damage. Consult an authorized service dealer in this case.

Fixing Ignition System Issues

Losing spark after the chainsaw initially starts is a sign of ignition failure. To resolve:

  1. Disconnect spark plug: Remove spark plug wire from end of plug.
  2. Check for spark: Reconnect wire to plug and lay it onto metal cylinder. Ensure the stop switch is RUN position. Pull the starter cord and watch for bluish spark at plug tip to ground.
  3. No spark? Swap in known-good spark plug. Retest. If still no spark, replace magneto/coil.
  4. Has spark? Clean debris off tip and electrode using wire brush. Re-gap to 0.5 mm.
  5. Check stop switch: Use a multimeter on OHMs setting to check for continuity between switch terminals. Replace stop switch if no continuity.
  6. Inspect wiring: Ensure insulation isn’t cracked on stop switch wires, spark plug boot, or magneto leads.

With good spark restored, the chainsaw should restart using normal procedure. Let it run for several minutes to confirm ignition issues are fully resolved.

Fixing Carburetor Issues

Carburetors regulate the fuel-air mixture entering the cylinder. Contaminants and worn parts throw off this calibration and prevent smooth running.To troubleshoot carburetor problems:

  1. Filter inspection: Check air filter isn’t overly dirty or soaked with oil. Replace filter if needed.
  2. Fuel lines: Ensure fuel pickup, return, and vent lines are intact without cracks or blockages.
  3. Filter screen: Remove and clean debris from fuel filter screen inlet.
  4. Carb inspection: Take carburetor off engine and open it. Check for dirt buildup in small passages and jets. Clean thoroughly using carb cleaner spray and compressed air.
  5. Needle/seat: Ensure float needle moves freely to seal against seat. No dirt or corrosion.
  6. Reassemble/replace: Reinstall carb and external lines. Replace any damaged gaskets or rubber diaphragms.

This typically resolves hard starting, rough running, stalling issues with clogged or malfunctioning carburetors. Use the standard starting procedure once fully reassembled.

Fixing Low Compression Issues

If your chainsaw lacks the cylinder pressure to start quickly or run properly, there are internal air leaks. To pinpoint:

  1. Pressure test: Use a gauge screwed into the spark plug hole. Healthy reading is 90-120 psi on most models. Lower means leaks.
  2. Locate leaks: Listen for hissing air noises. Check the intake/exhaust valves, head gasket, piston rings, and crank seals.
  3. Replace parts: Worn piston rings and leaky crank seals are common. May require splitting the crankcase to access. Consult service manual.
  4. Reassemble: Torque all fasteners to spec. Do pressure test again to confirm leaks are fixed adequately for restarting.

Significant air leaks that sap engine power necessitate repairs by an authorized small engine technician. They can precisely diagnose issues and rebuild internal components.

Preventive Chainsaw Maintenance

While many starting issues come without warning, you can avoid some problems with proper saw maintenance. Regular upkeep improves reliability and saves costly repairs down the road.Follow these maintenance tips to keep your chainsaw running strong:

  • Check fuel system: Monthly, inspect the fuel cap, lines, filters for leaks, cracks, blockages. Ensure vent holes are clear.
  • Clean air filter: Every 5 hours of runtime, clean the air filter. Replace yearly or if damaged.
  • Sharpen chain: File down any damaged cutters and restore proper depth gauge height every 5 hours of cutting work. This prevents overworking the engine.
  • De-gunk exhaust: Use a degreaser to dissolve oily buildup in the exhaust port/muffler every 25 hours. This prevents clogs that increase operating temperature.
  • Inspect sprocket: The clutch drum and bar nose sprockets wear over time. Replace them once excessive play develops to protect other parts.
  • Clean chassis: Use compressed air and low pressure water to blow out dust/debris from the engine cooling fins, starter housing, chain brake, and bar groove after each use.
  • Check hardware: Examine screws, bolts, mounts every 50 hours. Tighten any fasteners that have loosened from vibration.

Following the engine and bar chain oil change intervals stated in the owner’s manual is also critical. Good maintenance practices dramatically extend the operating life of your chainsaw.

FAQ: Chainsaw Starting & Operating Tips

Q: Why does my chainsaw bog down when cutting?

A: Frequent causes of bogging/stalling under load include a dull chain, inadequate oiling, bad fuel mix, and airflow restriction. Maintain proper chain sharpness and clear debris from the cover/guide bar. Also check the air filter and inspect fuel system components regularly.

Q: How do I adjust the carburetor on my chainsaw?

A: Refer to your owner’s manual for model-specific carburetor tuning procedures. In general: 1) Turn idle speed (T) screw clockwise until highest idle speed, then back out 1/4 turn; 2) Turn low speed (L) screw midrange; 3) Accelerate full throttle to adjust high speed (H) screw for max RPMs without sputtering.

Q: Why does my chain brake keep engaging during use?

A: If the chain brake activates unexpectedly, check the brake band isn’t overly worn. The system may be oversensitive if the band stretched. Also inspect the brake handle, springs, and linkages for damage or loose fasteners.

Q: How can I improve chainsaw cold weather starting?

A: Take steps to help vaporize fuel and protect components in cold temps: Remove bar/chain, store saw indoors overnight, use fresh winter-grade fuel, apply insulating foam covers, position air vents to block wind, slowly warm with primer puffs before starting.

Q: What oil ratio should I use for my chainsaw mix?

A: Check manufacturer specifications in the owner’s manual as ratios vary by model. Most modern saws use a 50:1 ratio of fuel to 2-stroke oil. For example, 1 gallon of gas to 2.6 fluid ounces of oil. Stick to engine oil grades recommended for air-cooled 2-stroke engines.

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