Leaf Blower Won't Start? What to Check

Part of our complete Small Engine Troubleshooting Guide.

Work through it in the order below and most of these turn up before a carburetor ever comes off.

1. Ten Months in a Shed Is the Whole Problem

A leaf blower is the most seasonal machine most people own. A mower runs weekly for six months; a blower comes out for a few weekends and then sits until the following autumn. Whatever is in the tank in November is still there the next October, and that is the difference between this machine and everything else in the shed.

Pump gasoline with ethanol in it draws moisture and goes stale in weeks rather than months. The light part evaporates, what is left turns gummy, and it dries to varnish in passages narrower than a pencil lead. Our guide to ethanol gas and small engines covers why that happens, and it is why a blower put away dry starts and one put away full does not.

2. Mix Fuel Fails in Two Different Ways

Most handheld blowers are two-stroke engines, which means the oil the engine needs for lubrication is mixed into the fuel rather than held in a crankcase. The ratio is whatever the maker specifies, commonly 40:1 or 50:1, and it is printed on the cap or in the manual. Premixed fuel stored a year old is stale in exactly the way straight gasoline is, and it can separate as well.

The second failure is worse, and it is a people problem rather than a storage one. A tank filled from the mower can, with no oil in it, will run beautifully for a few minutes and then do real damage. If a blower was running and stopped suddenly rather than simply refusing to start, that is worth ruling out before you spend money on fuel-system parts.

3. Work the Fuel Path, Not the Carburetor

Four things sit between the tank and the engine, and on a stored machine any of them can be the whole answer. All four are visible with the air filter cover off and a torch:

• The fuel in the tank. Drain it into a jar. If it smells sour, looks like weak tea or has water sitting under it, nothing else you do matters until it is gone.
• The pickup line inside the tank. The soft line with the weighted filter on the end goes hard and splits where it flexes. A cracked line draws air instead of fuel and the engine never gets a charge.
• The primer or purge bulb. It perishes, splits at the base and stops holding. If it will not firm up, or fuel does not visibly move through the clear line, it is not delivering anything.
• The in-tank filter. The little weighted strainer clogs with the same gum that varnished the carburetor. It is a cheap part and it is often the only one that needed changing.

4. Flooded, and Why the Mower Routine Makes It Worse

A handheld two-stroke floods far more easily than a mower, because the primer bulb pushes raw fuel straight at the carburetor rather than filling a bowl. The usual sequence is that it does not start, so it gets more primer and more choke, and after a dozen pulls the cylinder is wet.

The tell is a plug that is wet with fuel and a single cough early on, followed by nothing. Clear it by turning the choke fully off, holding the throttle wide open and pulling steadily, which draws air with almost no extra fuel. If that does not do it, take the plug out, dry it, pull the cord a dozen times to air the cylinder and refit it. Pulling harder on a flooded engine only risks the starter, and our guide to recoil starters and pull cords covers what gives way when it does.

5. Spark, and the Screen Nobody Checks

Pull the plug and look at it. Dry and light brown is healthy. Wet means flooding. Black and sooty points at a rich mixture or a choked air filter. Heavy carbon on a plug that has done several seasons is simply a plug at the end of its life, and it is the cheapest part on the machine.

Then look at the spark arrestor screen, the small wire mesh behind the muffler. It is the most overlooked part on any handheld two-stroke, and on an older machine it packs solid with carbon until the engine cannot push exhaust out. Blocked, it usually shows up as an engine that starts and dies within seconds rather than one that never fires at all, but it takes two minutes to check.

6. Starts and Dies, or Only Runs on Choke

An engine that catches and then quits has fuel in the carburetor and nothing behind it, so look at supply: the tank filter, the pickup line, the bulb. An engine that will only keep running with the choke held on is telling you the opposite. Choke makes the mixture richer, so if that is the only way it runs, it is not getting enough fuel the normal way.

On these carburetors that is usually a hardened diaphragm or a blocked passage rather than a float or a bowl, because a handheld carburetor has to work at any angle. Our guide to small engine carburetor cleaning and repair covers the job, and a diaphragm kit usually beats cleaning alone on a machine that has sat a year.

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What the Pull Cord Is Telling You

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When to Call the Shop

Draining old fuel and refilling with fresh mix, changing a spark plug, clearing a flooded engine, swapping a primer bulb and cleaning the arrestor screen are all driveway jobs, and between them they account for most of the blowers that will not start in October.

Bring it in when it still will not run on fresh fuel and a new plug, when the pickup line has broken off inside the tank, when the carburetor needs a diaphragm kit, when the starter has given up, or when you suspect a tank of straight gasoline went through it, which is worth a compression check before anyone buys parts. While it is here is the sensible moment to get the rest of the leaf blower and string trimmer service done.

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Leaf Blower No-Start FAQ

Why won't my leaf blower start after sitting all winter?
Almost always the fuel. Mix fuel goes stale in weeks, and what is left behind turns to varnish in the carburetor and hardens the pickup line in the tank. Fresh fuel and a look at the primer bulb settle most of them.

Can I put regular gas in a leaf blower?
Not in a two-stroke. The oil the engine needs for lubrication is mixed into the fuel, so a tank of straight gasoline runs for a few minutes and then does real damage. Check the cap or the manual for the ratio your machine wants.

How do I clear a flooded leaf blower?
Turn the choke fully off, hold the throttle wide open and keep pulling, which draws air with no extra fuel. If it will not clear, take the plug out, dry it, pull the cord a dozen times to air the cylinder and refit it.

Do you repair leaf blowers in Richmond, KY?
We do, across Madison County. Carburetor work, fuel lines, primer bulbs, arrestor screens, ignition and recoil starters on handheld equipment, with pickup and delivery available and a firm quote before any work begins: (859) 661-8877.