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Fix a chainsaw that will not cut

We'll rule out dull chain, chain tension, bar oil, and bar damage—then isolate the cause or tell you when to call a mechanic.

Troubleshooting · Home appliances
20–60 min
What you'll need
  • Round file and file guide (for chain sharpening)
  • Screwdriver or wrench (for tension adjustment)
  • Bar oil
  • Replacement chain or bar (if damaged)
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Steps

Goal: Confirm the engine runs but wood is not cut, then check chain, tension, and bar oil.

  • Start the engine and run the chain against a log. Note whether it cuts, produces fine dust, or does not bite.
  • Good: Engine runs but chain does not cut—chain or bar issue. Proceed to Check chain.
  • Bad: Engine does not run—see fix-chainsaw-will-not-start.

Check chain

Goal: Inspect chain sharpness and tension.

  • Disconnect the spark plug before any work on the chain.
  • Inspect the cutters. Sharpen with a round file and file guide at the angle in your manual.
  • Check chain tension—snug against the bar but with slight slack when cold. Adjust the tension screw.
  • Good: Chain is sharp and tensioned. Proceed to Check bar oil.
  • Bad: Dull or loose—sharpen or adjust.

Check bar oil

Goal: Confirm bar oil flows to the chain and bar.

  • Check the bar oil tank is full. Run the saw at full throttle and point the tip at a light surface—you should see a thin line of oil.
  • Clean the bar oil holes and groove if blocked.
  • Good: Oil flows. Proceed to Check bar.
  • Bad: No oil—clean passages or the oil pump may have failed.

Check bar

Goal: Inspect the bar and drive sprocket for wear.

  • Inspect the bar for wear, bent rails, or a damaged groove. Flip the bar to wear both sides. Replace if worn past the marks.
  • Check the drive sprocket for hooked or worn teeth. Replace if damaged.
  • Good: Bar and sprocket are in good condition. Retest cutting.
  • Bad: Bar or sprocket worn—replace.

When to get help

Call a mechanic if:

  • The chain is sharp and tensioned correctly but still does not cut.
  • The bar is severely worn or damaged.
  • The oil pump has failed.
  • You are not comfortable working on the chainsaw.

Verification

  • The engine runs and the chain spins when you pull the throttle.
  • The chain cuts wood cleanly and produces chips, not fine dust.
  • Bar oil flows and the chain stays cool.

Escalation ladder

Work from the device outward. Stop when the problem is fixed.

  1. Confirm symptom Verify engine runs but wood is not cut; rule out engine problems.
  2. Chain sharpness Sharpen the chain with a round file and file guide.
  3. Chain tension Adjust chain tension per the manual.
  4. Bar oil Check oil level and flow; clean oil passages.
  5. Bar and sprocket Inspect bar and drive sprocket for wear.
  6. Call a pro Chain sharp, tension good, oil flows—still no cut; oil pump or bar damaged.

What to capture if you need help

Before calling support or posting for help, have these ready. It speeds everything up.

  • Engine runs or not
  • Chain spins or not
  • Chain condition (dull, loose)
  • Bar oil flow
  • Bar condition
  • Steps already tried

Does the engine run but the chain does not cut wood?

Start the engine and run the chain against a log. Check if it cuts or just spins.

Start the engine and run the chain against wood. Good: Engine runs but chain does not bite or produces fine dust—chain or bar issue. Bad: Engine does not run—different problem (see fix-chainsaw-will-not-start).

Yes No

You can change your answer later.

Engine does not run — see fix-chainsaw-will-not-start

The engine does not run—different problem. See fix-chainsaw-will-not-start for troubleshooting a chainsaw that will not start.

Done

Does the chain spin when you pull the throttle?

The chain should spin at full throttle.

Pull the throttle. Good: Chain spins—dull chain, tension, or bar oil. Bad: Chain does not spin—clutch or drive sprocket fault.

Yes No

You can change your answer later.

Is the chain sharp and properly tensioned?

A dull chain produces fine sawdust. Loose chain cuts poorly.

Check chain sharpness and tension. Sharpen if dull; adjust tension per manual. Good: Chain sharp and tensioned. Bad: Dull or loose—sharpen or adjust.

Yes No

You can change your answer later.

Sharpen chain and adjust tension

Sharpen with round file and file guide. Adjust tension per manual. Retest cutting.

Done

Is bar oil flowing?

Low or blocked oil overheats the chain and bar.

Check oil level. Run at full throttle and point tip at light surface—look for oil line. Clean oil holes if blocked. Good: Oil flows. Bad: No oil—clean passages or check oil pump.

Yes No

You can change your answer later.

Fix bar oil

Fill oil tank. Clean bar oil holes and groove. If still no flow, oil pump may have failed—call a pro.

Done

Is the bar in good condition?

A worn or damaged bar causes poor cutting.

Inspect bar for wear, bent rails, damaged groove. Replace if worn past marks. Good: Bar good. Bad: Bar worn or damaged—replace.

Yes No

You can change your answer later.

Replace bar

Replace the bar with a matching size. Retest cutting.

Done

Check clutch and drive sprocket

Chain does not spin: check clutch and drive sprocket. Replace if worn. Call a pro if needed.

Done

Call a mechanic

Chain sharp, tension good, oil flows, bar good—still no cut. Call a small-engine mechanic.

Done

Reviewed by Blackbox Atlas

Frequently asked questions

Why would a chainsaw run but not cut?
Common causes: dull chain, incorrect chain tension, low or blocked bar oil, or a damaged bar. A dull chain produces fine sawdust and burns the wood. A loose chain can derail or cut poorly. Low bar oil overheats the chain and bar.
Can I fix a chainsaw that will not cut myself?
Yes. You can sharpen the chain, adjust tension, and check bar oil with basic tools. Use a round file and file guide for sharpening. Check your manual for the correct tension and filing angle. Bar replacement needs basic hand tools.
When should I call a mechanic for a chainsaw that will not cut?
Call a mechanic if the chain is sharp and tensioned correctly but still does not cut; if the bar is damaged or worn; or if the oil pump has failed and you are not comfortable repairing it.

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