Leaf Blower Won't Start? 6 Causes and Fixes

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Last updated October 28, 2026 · Applies to: leaf blowers from Toro, Husqvarna, Troy-Bilt, Craftsman, Echo and Stihl

Cause 1: Old or wrong fuel mix

Step-by-step instructions for this cause are being written.

Fuel path: tank to cylinder: Fuel tank → Cap vent → Shut-off valve → Fuel filter / line → Carburetor bowl → Main jet → Intake → cylinderFuel tankfresh fuelCap ventlets air inShut-off valveopen?Fuel filter / lineno cracksCarburetor bowlfloat + needleMain jetmeters fuelIntake → cylinderfuel + air
Fuel path: tank to cylinder. Fuel must flow through every stage. A blockage at any box starves the engine.

Cause 2: Cracked primer bulb

Step-by-step instructions for this cause are being written.

Primer and choke circuit: Fuel tank → Primer bulb → Return line → Carburetor → Choke plate → Run positionFuel tankpickup linePrimer bulbfills with fuel?Return lineback to tankCarburetorpriming portChoke plateclosed to startRun positionchoke open
Primer and choke circuit. A cracked primer bulb pushes air, not fuel. The choke must open once the engine fires.

Cause 3: Fouled spark plug

Step-by-step instructions for this cause are being written.

Ignition path: magnet to spark: Flywheel magnet → Ignition coil → Stop / kill wire → Plug lead & boot → Spark plug → CombustionFlywheel magnetkey aligns timingIgnition coilair gap to flywheelStop / kill wiregrounds coilPlug lead & boottight fitSpark pluggap + conditionCombustionspark ignites mix
Ignition path: magnet to spark. Test the end of the chain first: a spark tester on the plug lead.

Cause 4: Clogged air filter

Step-by-step instructions for this cause are being written.

Air intake path: Air filter cover → Pre-filter / foam → Paper filter → Carburetor throat → Intake gasket → CylinderAir filter coverclips / screwPre-filter / foamclean, oiledPaper filternot oil-soakedCarburetor throatchoke plateIntake gasketno air leaksCylinderintake valve / port
Air intake path. A restricted filter richens the mixture; a leak after the carburetor leans it out.

Cause 5: Blocked spark arrestor

Step-by-step instructions for this cause are being written.

Exhaust and spark arrestor: Cylinder → Exhaust port → Muffler → Spark arrestor screen → OutletCylindercombustionExhaust portcarbon build-upMufflerbafflesSpark arrestor screenfine meshOutletfree flow
Exhaust and spark arrestor. Carbon on the screen chokes the exhaust: the engine idles but bogs at full throttle.

Cause 6: Gummed carburetor

Step-by-step instructions for this cause are being written.

Inside a float-bowl carburetor: Fuel inlet → Needle & seat → Float → Float bowl → Main jet → Emulsion tube → Venturi / throttleFuel inletfrom tankNeedle & seatshuts off flowFloatsets fuel levelFloat bowldrain screwMain jettiny orificeEmulsion tubemixes airVenturi / throttleto intake
Inside a float-bowl carburetor. Varnish from old fuel usually blocks the main jet or emulsion tube first.

Which cause is it?

The decision table is being compiled from shop pricing and manufacturer data.

Brand notes

Brand-specific notes for Toro, Husqvarna, Troy-Bilt and Craftsman are being researched.

When to take it to a shop

Hand it over if the engine still will not run after the fuel, spark and air checks, if you find metal in the oil or the engine is seized, or if the machine is under warranty (opening it yourself can void it).

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Frequently asked questions

Answers being written: Why won't my leaf blower start after storage? · How do I prime a leaf blower? · What fuel mix do leaf blowers use? · Should I replace or clean the carburetor?