Here is the sentence that reorganizes the whole problem, and almost no troubleshooting page leads with it: a leaf blower is not an engine that blows air. It is two machines bolted together — an engine (or an electric motor) that makes a spin, and an air pump that turns that spin into moving air. The air pump is just a fan — an impeller — spinning inside a spiral housing. It pulls a large volume of air in through a screened intake and shoves it out the nozzle. The engine's whole job is to spin that fan fast; the fan does the actual work of moving leaves.
Once you see the blower as two machines, the complaint "it has no power" splits into two completely different problems that happen to feel the same in your hands. Either the engine is running fine but the air isn't getting through (an air-pump problem — usually a cheap blockage), or the engine itself is struggling (a fuel problem, almost always). People lump both under "weak engine, buy a new blower," and that is how a working machine ends up at the curb.
So before you touch anything, you sort your symptom with one question.
The one question that decides everything: does the engine run, or does it struggle?
Start it (or trigger the motor) and listen, without worrying yet about the air.
The engine RUNS and revs — but little or no air comes out → it's the AIR side
The motor sounds normal, maybe even revs up cleanly, but the tube barely puffs. That is not an engine problem at all — the engine is doing its job and the air is being choked somewhere between the intake and the nozzle. This is the family people never suspect, because "no air" sounds like "no power." The fixes here are the cheapest on the whole tool, and several are free.
The engine BOGS, won't rev, or won't start → it's the ENGINE side (almost always fuel)
It coughs and dies when you open the throttle, refuses to climb to full speed, or won't catch at all after sitting. That is the engine genuinely not making power — and on a small engine, "not making power" is a fuel story far more often than a broken-parts story. Stale gas, a wrong mix, a clogged carburetor, a sooted exhaust screen: all cheap, none of them a dead engine.
The one thing that actually kills a two-stroke — and it's the fix people reach for
This is the most important paragraph on the page, so it goes before the repairs. A two-stroke blower engine — the kind in most handheld and backpack gas units — has no oil sump. It gets all of its lubrication from oil that is pre-mixed into the fuel. That is why you buy special two-cycle oil and blend it into the gas at the ratio printed on the cap.
So when a blower won't run and someone "just puts some gas in it" from the can they use for the car or the mower — straight gasoline, no two-stroke oil — the engine now runs with no lubrication. It will feel crisp and strong for a few minutes, throw almost no smoke, and then the piston and cylinder overheat, gall, and seize — metal welding to metal, the engine locked solid, permanently. This is the one mistake that turns a fixable problem into a genuinely dead engine, and it is the one the frustrated owner is most tempted to make. Never run straight gas in a two-stroke, not even "just to test it."
The opposite mistake — too much oil in the mix — is loud and alarming but harmless by comparison: heavy smoke, a reluctance to rev, a plug that fouls black and oily, carbon building up over time. Annoying, not fatal. So if you're going to err, err rich. But the right answer is neither: match the exact fuel-to-oil ratio your engine calls for (it varies by brand and model — it's on the cap or in the manual), mixed with fresh fuel and proper two-cycle oil.
Fix family — the engine RUNS but the air is weak (cheapest, start here if it applies)
Everything here assumes the engine is fine. You're clearing the air pump. On gas units, stop the engine first; on electric, unplug it or pull the battery before you go near the intake or impeller — the fan is spinning fast and it does not care about your fingers.
The intake screen is clogged
The air the blower throws all comes in through a screened intake on the side or back of the housing. Fine dust, grass, and shredded leaf pack that screen solid, and airflow drops off a cliff. On electric and battery blowers this is doubly bad: the same intake air cools the motor, so a blocked screen doesn't just weaken the blast, it makes the motor overheat — which on a battery unit trips a thermal cutoff and the tool shuts itself off (more on that below). Brush or vacuum the screen clean. This is the number-one free fix on the air side.
The impeller is jammed or damaged
If something got sucked into the intake — a wad of wet leaves, a twig, a pebble on a blower/vac model — it can wedge against the impeller and choke or stop the airflow, sometimes with a new vibration or rattle. With the engine off and power removed, clear anything lodged around the fan. A fan with chipped or broken vanes will never move air properly and needs replacing (a part, not a new blower).
The tube is missing, cracked, or not seated
Sounds too simple to be real, and it's shockingly common: a blower tube that isn't locked fully onto the housing, or is cracked, leaks its air out the gap instead of the nozzle. Some designs actually lose velocity if the concentrator nozzle fell off. Check the tube is clicked home and intact — this is where the tube-off test earns its keep.
(Electric only) the extension cord is starving it
A corded blower on a long or thin extension cord suffers voltage drop — the motor gets less than its rated power and runs weak and hot. If a corded unit feels gutless, try it on a short, heavy-gauge cord (or a closer outlet) before condemning it. It's the most-overlooked "weak motor" that isn't a motor problem at all.
...and one "fault" that isn't a fault: wet, matted leaves
No blower moves a soaked, matted leaf pile the way it moves dry leaves, and no amount of MPH fixes that — wet leaves are heavy and stuck down. If your blower struggles only on wet piles and is fine on dry, nothing is wrong with it. That's a job for volume of air (CFM) and patience, and it's exactly why our buying guide argues CFM matters more than the big MPH number on the box.
Fix family — the engine BOGS, won't rev, or won't start (fuel first, cheapest-first)
Work this list in order. The top of it fixes the large majority of gas-blower complaints.
1. Stale fuel — the reason most stored blowers "die"
Modern pump gas contains ethanol, which absorbs water and breaks down as it sits. Left in the tank over a season it oxidizes into a gummy varnish and pulls in moisture, and those deposits clog the pinhole-sized passages in the carburetor. A blower that ran fine last fall and won't start this fall usually has nothing wrong but the fuel that's in it. Drain the old fuel, refill with fresh, correctly-mixed fuel, and try again. This one step revives a large share of "dead" blowers. Going forward: run the tank dry before storage, or use fresh fuel with a stabilizer, and consider ethanol-free fuel for a tool that sits a lot.
2. Clogged carburetor, fuel filter, or fuel lines
If fresh fuel alone doesn't do it — it starts then stalls, or won't draw fuel — the varnish has already settled in. The little fuel filter in the tank clogs; the rubber fuel lines go hard and crack (ethanol rot); the primer bulb splits and won't pull fuel. These are all cheap parts. A carburetor can be cleaned, rebuilt with an inexpensive kit, or replaced outright — a carb for a small engine costs a small fraction of a new blower.
3. The spark-arrestor screen is sooted over (the classic "bogs under load")
Gas blowers have a tiny wire screen in the muffler — the spark arrestor — that stops hot carbon from flying out. It slowly cakes with soot, especially if the fuel mix runs rich. A clogged arrestor traps exhaust, and the engine can't breathe out: it starts, idles, then bogs and dies the moment you ask for full throttle. This one masquerades perfectly as a "tired engine." Remove the screen and clean it (a wire brush, or carefully burning the carbon off) or replace it — it's one of the cheapest parts on the tool. Let the muffler cool completely first; it's hot enough to burn you.
4. Clogged air filter
A filthy air filter chokes the engine's intake air, making it run rich — bogging, black smoke, weak power. Pop it out, clean or replace it. Pennies, two minutes.
5. Fouled spark plug
An old plug, or one fouled black by too-rich a mix, gives a weak spark — hard starting, misfiring, no power. A new plug is a couple of dollars. If the plug keeps fouling black, that's your clue the mix is too oily (see the fuel-ratio note above).
Battery and electric: "cutting out" is usually protection, not failure
A battery blower that runs, then shuts off, then runs again is very often hitting its thermal cutoff — a safety that kills power when the motor or battery gets too hot, and resets once things cool (often in the range of half an hour, or via a reset button). The most common cause of the overheat is a clogged intake screen (back to the air side) or simply running flat-out without a break. Let it cool, clear the intake, and it comes back. Weak run time or power on a battery unit is usually a tired or cold battery, not a dead tool.
Read your symptom
| What it's doing | Most likely cause | First move | New blower? |
|---|---|---|---|
| Engine runs and revs normally, but almost no air comes out | Air side: clogged intake screen or jammed impeller | Stop it, clear the intake screen and fan | No |
| Strong air at the housing, weak out the nozzle | Tube cracked, unseated, or nozzle missing | Re-seat / replace the tube; check it's clicked home | No |
| Won't start (or starts and stalls) after sitting since last season | Stale ethanol fuel gumming the carburetor | Drain old fuel, refill with fresh correct mix | No |
| Idles fine, then bogs and dies at full throttle | Sooted spark-arrestor screen (can't exhale) | Clean or replace the arrestor screen (cool first) | No |
| Bogs, black smoke, generally rich and weak | Clogged air filter or too-oily fuel mix | Clean/replace air filter; check your mix ratio | No |
| (Battery) runs, shuts off, runs again after cooling | Thermal cutoff — often from a clogged intake | Let it cool, clear the intake, work in bursts | No |
| (Corded) feels gutless, motor runs hot | Voltage drop on a long / thin extension cord | Use a short, heavy-gauge cord or closer outlet | No |
| Was run on straight gas; now locked solid, won't turn over | Seized two-stroke (no lubrication) | Engine is likely done — see below | Maybe — this is the real exit |
When it really is time for a repair — or a new blower
Airflow blocks and fuel explain the large majority of "no power" blowers. Treat it as a genuine end-of-life case when:
- A two-stroke seized from straight gas or a missed mix. If it ran without oil and is now locked solid with no compression, the engine is done. On a cheap handheld that's usually a replacement; on a good backpack unit a rebuild can be worth pricing. Either way, the lesson is prevention — this is the failure you never have to have.
- The housing or impeller is broken. A cracked-through housing, a warped or chipped impeller you can't source a part for, or a stripped tube mount can push a bargain blower past worth-fixing. On a mid-range or better tool, the impeller and housing are usually available parts.
- A corded motor has genuinely burned out — smells scorched, hums without turning, or the brushes are gone — after you've ruled out the cord and a clogged intake. Then it's repair-vs-replace on price.
- It was never big enough for your yard. If a healthy blower simply can't keep up with a large lot or wet leaves, that's not a fault, it's a sizing mismatch. Our leaf blower buying guide covers reading CFM honestly, handheld vs. backpack, and gas vs. battery vs. corded — so the replacement actually fits the work.
For everything short of that, the honest answer is the cheap one. A blower is an air pump and an engine, and the two things that go wrong most — a blocked airflow path and stale fuel — cost between nothing and a few dollars to fix. Get the fuel right, keep the intake clear, and most "dead" blowers have years left in them.