Symptoms
- Engine slows or nearly stalls in thick or tall grass
- Runs fine on light grass or idle
- Recovers once you back off or raise the deck
- May smoke or smell rich when it bogs
Likely causes
- CommonClogged air filterRestricted airflow limits how much power the engine can produce under load.
- CommonCutting height too low for grass lengthTrying to remove too much grass in one pass overloads the blade and engine.
- PossibleDirty carburetor or fuel restrictionPartial blockages can limit fuel delivery exactly when more is needed.
- PossibleDull bladeA dull blade works harder to cut the same grass, straining the engine more than necessary.
What to do
- Raise the cutting height, especially if the grass is more than a third taller than your normal cut height.
- Check and clean or replace the air filter if it's dirty.
- Sharpen or replace the blade if it hasn't been serviced this season.
- Slow your walking speed in thick areas to give the engine time to keep up.
- Check the fuel for freshness and the fuel filter (if equipped) for clogging.
- If bogging continues with a clean filter, sharp blade, and correct height, the carburetor may need cleaning.
Tools and parts
- Replacement air filter
- Blade sharpening file
Small engine air filterSearch: “lawn mower air filter”
Replacement mower bladeSearch: “lawn mower blade”
When to call a pro
If the engine still bogs after basic maintenance, a small engine shop can check carburetor tuning and engine power output.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.