Leaf Blower Runs But Won't Blow? What to Do

Part of our complete Small Engine Troubleshooting Guide.

This is the list for a blower that runs properly and moves no air. If it will not start at all, our guide to a handheld two-stroke that will not start is the right place to begin instead. Work down this list in order: the free answers sit at the top of it, and the engine sits at the bottom for a reason.

1. It Is an Air Pump, Not an Engine

A blower is a wheel in a housing with a hole at each end. Air comes in at the intake, gets thrown outward by the impeller, and leaves down the tube. Anything that restricts the way in, leaks on the way out, or damages the wheel in the middle costs you air without costing you revs.

That is why the engine is the last suspect here rather than the first. An engine fault usually announces itself: it bogs, it will not hold revs, it smokes. A machine that sounds right and blows nothing is nearly always a blocked intake, a bad joint or a damaged wheel.

2. The Intake Screen and the Air Filter

Two separate restrictions and people check neither. The intake screen feeds the impeller; the air filter feeds the engine. Both clog with the same fine leaf dust.

• The intake screen or grille. Brush it clean, both sides. Dry leaf dust mats into it like felt and halves the output.
• Lint and grass behind the screen. Look through it with a light; sometimes the mat is on the inside face.
• The air filter. A choked filter makes the engine weak as well, so it reads as a general loss of everything.
• Where you set it down. Resting a running blower on cut grass or loose leaves pulls them straight onto the screen.

3. Tubes, Nozzle and the Vacuum Door

Every joint between the housing and the nozzle is a place air can escape, and a leak you cannot hear over a two-stroke is still a leak. Tubes have to be pushed fully home and twisted to lock, and a tube that has only been pressed together will blow apart its seal under load without ever falling off.

Check the rubber coupling at the housing for splits, look along each tube for a crack, and count the extension tubes: a long run on a small machine trades air speed for nothing. If the machine doubles as a vacuum, the big one is the door or the inlet cover. Left unlatched, or left with a worn seal, it is a hole the size of your hand feeding air straight back out of the housing.

4. The Impeller Behind the Housing

The wheel is what actually moves the air, and it lives one cover away. Taking that cover off is a five-minute job on most handhelds and it is worth doing once the easy checks come up clean:

• Chipped or broken fins. Gravel and acorns through a vacuum intake take pieces out of the blades, and a wheel missing fins moves far less air.
• Caked debris. Wet grass and leaf pulp set hard between the blades and ruin the shape the fin relies on.
• A wheel loose on its shaft. If the fastener or the key has worked loose, the wheel lags behind the engine. Expect a rattle or a scrape.
• Rubbish in the housing. A twig wedged against the wheel both robs output and chews the blade it is touching.

5. An Engine That Is Not Reaching Full Speed

Airflow climbs steeply with wheel speed, which means a small loss of engine speed shows up as a big loss of air. A machine down a modest amount on revs can feel like it has lost half its blow, and that mismatch is what sends people looking for a hole that is not there.

The usual causes are the familiar two-stroke ones: a spark arrestor screen part-blocked with carbon, last season's mix fuel, a carburetor out of adjustment after sitting, or carbon built up in the exhaust port. The tell is sound rather than sight. An engine that will not climb to a clean high note, or one that starts strong and fades as it heats up, is telling you the problem is the engine after all.

6. When Nothing Is Actually Wrong

Two honest cases worth naming. Wet, matted leaves are a different job from dry ones: water locks a leaf to the ground and to its neighbours, and a machine that cleared the same driveway last week in the dry can look broken in the damp.

The other is size. Air volume is what rolls a pile along; air speed is what lifts matted debris off the surface. A small handheld asked to do an acre of wet oak leaves is not faulty, it is outmatched, and no amount of cleaning changes the answer. Our leaf blower and trimmer tune-up guide covers getting the most out of the machine you have.

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Matching the Symptom to the Cause

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When to Call the Shop

Brushing out an intake screen, fitting a clean air filter, locking the tubes together properly and latching a vacuum door are all driveway jobs, and between them they account for most of the blowers carried in here in November. Clean the arrestor screen while you are there and you have covered the common list for the price of nothing at all.

Bring it in when the impeller has lost fins or has gone loose on its shaft, when the housing is cracked, when the engine will not reach a clean high note after fresh fuel, or when it fades away as it warms up. A damaged wheel is worth a look sooner rather than later, because an out-of-balance impeller works on its bearings every minute the machine runs.

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Leaf Blower Airflow FAQ

It starts and revs fine but barely moves air. Where do I start?
The intake screen on the housing, then that the tubes are locked together and the vacuum door is latched. Those three cost nothing and fix most of them.

Can a leaf blower impeller be replaced?
On most machines, yes. Fins chipped by gravel or a wheel gone loose on its shaft are bench work, and you get a firm quote before anything is ordered.

Does a blocked spark arrestor really cut airflow?
Indirectly, and more than people expect. It chokes the exhaust, the engine cannot reach full speed, and air output falls off faster than the revs do.

Do you service leaf blowers in Richmond, KY?
We do, across Madison County: intakes, impellers, carburetors and arrestor screens, with a firm quote before any work begins. Call (859) 661-8877.