String trimmer or leaf blower won't start

Q: String trimmer or leaf blower won't start

In Canada, when a 2-stroke string trimmer or leaf blower won't start after storage, the most common cause is stale fuel or the wrong oil mix gumming the carburetor — drain it and run fresh, correctly-mixed 2-stroke fuel. Before that, run the full start sequence (primer bulb, choke, switch on). A fouled spark plug and a clogged air filter are the next things to rule out. Never run a gas engine in an enclosed space, and always use the correct oil-to-gas ratio — straight gas destroys these engines.

After a winter in the shed, most no-starts come down to stale fuel — a cheap fix, not a dead tool.

tuneWhat are you noticing?

Select anything that matches and the checklist below reorders to fit. Not sure? Skip it.

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In Canada, suspect the fuel first — especially after off-season storage. Drain the old fuel, and refill with fresh gasoline mixed to the exact 2-stroke ratio on the cap (often 50:1). If it still won't run, the carburetor likely needs cleaning. Using straight gas or old mix is the number-one killer of these engines.

Ranked from real-world failure data. The order updates as you select what you’re noticing above.

Likely causes, in the order to check them

Showing the typical order

Beginner-friendly Doable, with care Safety-critical Call a pro

handymanHow to fix it

Drain the old fuel into an approved container, refill with fresh gasoline mixed to the exact 2-stroke ratio on the cap, prime, and start. If it still won't run, clean or rebuild the carburetor (or have a small-engine shop do it).

Outdoors, drain the old fuel from the tank into an approved container for disposal — never down a drain.
Mix fresh gasoline with 2-stroke oil at the exact ratio printed on the fuel cap or in the manual (commonly 50:1). Straight gas or an old bottle of pre-mix will not do.
Refill, press the primer bulb several times, set the choke for a cold start, and pull. Move the choke off once it catches.
If it still won't run, the carburetor is likely gummed — clean it with carb cleaner and a rebuild kit, or take it to a small-engine shop.

schedule25 min savings$8–20

2-stroke engine oil (for fuel mix)Match the ratio on your tool's cap (e.g. 50:1); use fresh fuel

visibilityHow to check

warning Disconnect the plug before you work near the engineAlways pull the spark-plug boot off before touching the cutting head, carburetor, or plug — it stops the engine from firing unexpectedly. Work outdoors, with the engine cool, away from flames or sparks since you'll be near fuel.

Let the engine cool, then pull the rubber boot off the spark plug so it can't fire.
Unscrew the plug with the right socket and look at the tip: light tan is healthy; black soot or a wet fuel-soaked tip is fouled.
Clean a lightly-fouled plug with a wire brush and reset the gap per the manual, or replace it — they're only a few dollars.

buildNo tools schedule10 min

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Why the list is in this order

We don’t sort by likelihood alone. We sort the way a good, honest tradesperson thinks: rule out the free, safe, common causes first. That’s why the cheap checks outrank the expensive repairs — and why anything dangerous gets a hard stop instead of a pep talk. The order exists to save you money, not to sell you anything.