Leaf blowers are simple machines, but they're also the most neglected piece of outdoor power equipment in most garages. A little maintenance keeps them starting easily and blowing hard for years. Here's what to do.
Two-Stroke vs. Four-Stroke: Know What You Have
First, identify your blower type — the maintenance is different:
Two-stroke (most handheld blowers): The fuel is a gas/oil mixture (typically 50:1). There's no separate oil reservoir. The oil lubricates the engine as it burns with the fuel.
Four-stroke (some backpack and walk-behind blowers): Uses straight gasoline. Has a separate oil reservoir like a lawn mower. Check the oil before each use.
If you're not sure, check the fuel cap — it will say "oil mix" or have a ratio marked on it. Two-stroke blowers are far more common for homeowners.
Two-Stroke Leaf Blower Maintenance
Fuel Mix (Critical)
Using the wrong fuel mix is the #1 killer of two-stroke engines:
- Too little oil — the engine seizes from lack of lubrication
- Too much oil — the engine smokes heavily, fouls the spark plug, and loses power
Use the ratio specified in your manual — typically 50:1 (2.6 oz of two-stroke oil per gallon of gas). Some older blowers use 40:1 or 32:1 — always check.
Use fresh, correctly mixed fuel. Fuel that's been sitting for more than 30 days will cause starting problems. Mix only what you'll use in a month, and add fuel stabilizer if you won't use it all.
Air Filter
Check the air filter every 25 hours or monthly:
- Foam filter: Wash in soapy water, rinse, dry, and apply a light coat of two-stroke filter oil
- Felt filter: Tap to remove dust. Replace when it's visibly dirty or discolored.
A clogged air filter reduces blower power and causes the engine to run rich.
Spark Plug
Replace the spark plug every season or 100 hours. Two-stroke engines foul plugs faster than four-strokes because the oil burns with the fuel. Check the gap (typically 0.025" for two-strokes) and replace if the plug is fouled.
A fouled plug is the most common cause of a blower that won't start. If your blower has been sitting and won't start, check the plug first.
Spark Arrestor Screen
Two-stroke blowers have a spark arrestor screen in the muffler that prevents sparks from exiting the exhaust. Over time, carbon buildup clogs this screen and reduces power dramatically.
To clean:
- Remove the muffler cover and the spark arrestor screen
- Burn off the carbon with a propane torch, or scrape it with a wire brush
- If the screen is damaged or won't clean, replace it (about $5)
A clogged spark arrestor is a common cause of a blower that starts fine but has no power.
Four-Stroke Leaf Blower Maintenance
Four-stroke blowers use the same maintenance as a lawn mower:
- Check the oil before each use — change it every 50 hours or annually
- Use straight gasoline — never mix oil into the fuel
- Clean or replace the air filter every 25 hours
- Replace the spark plug annually
- Use fuel stabilizer before storage
Before Storage
Two-Stroke
- Drain the fuel tank and run the blower until it stops — this empties the carburetor
- Clean the air filter
- Remove the spark plug and add a few drops of two-stroke oil into the cylinder. Pull the starter cord slowly to distribute the oil. Reinstall the plug.
- Store in a dry location
Four-Stroke
- Add fuel stabilizer and run for 5 minutes
- Change the oil
- Clean the air filter
- Store in a dry location
Common Problems and Quick Fixes
Won't start: Check the fuel mix (is it fresh and correctly mixed?), then the spark plug, then the air filter. If all three are good, the carburetor may be clogged.
Starts but dies: Usually a clogged carburetor from stale fuel. Clean the carburetor.
Low power: Check the air filter, spark arrestor screen, and fuel mix. A clogged spark arrestor is a very common cause of power loss.
Smokes excessively: Too much oil in the fuel mix, or the engine is worn and burning oil. Correct the mix first.
The Bottom Line
Leaf blower maintenance is simple: use the correct fresh fuel mix (two-stroke), keep the air filter clean, replace the spark plug annually, and clean the spark arrestor screen. Do those four things and your blower will start on the second pull every time.