Gas Leaf Blower Running Rough? Here Are 5 Reasons Why

Home » Gas Leaf Blower Running Rough? Here Are 5 Reasons Why

As we move into autumn, many of us are keeping an eye out for “peak color”, that time of the season when the colors of the leaves are at their most vibrant. The breathtaking beauty of the reds, yellows, and oranges are caused by the leaves ceasing their production of Chlorophyll cells, which will eventually lead to… yep, that’s right, layers of dried, brown leaves covering your driveway and lawn!

Before you’re wading through calf-high drifting piles of dead leaves just to take out the trash, you’re going to want to make sure your gas-powered leaf blower is up to the task of clearing all that natural debris. Since you probably haven’t used that leaf blower in the past nine or ten months, you may find the blower’s engine is running rough. How can you keep the leaf blower engine running smoothly? Read on.

How does the leaf blower engine work, anyway?

To properly maintain a gas-powered leaf blower, you first need to understand how the engine works. Since most blowers are intended to be hand-held and operated at different angles, gas-powered ones will use a two-cycle engine (as opposed to a larger four-cycle engine) to reduce the weight of the equipment. Unlike a four-cycle engine, a two-cycle engine requires the gas to be mixed with oil for the engine to operate properly. Attempting to run a two-cycle engine without a suitable gas and oil mixture will cause the engine to seize due to insufficient lubrication. If you find the idea of getting an accurate gas/oil balance daunting, there are pre-mixed fuel and oil products like TRUFUEL 50:1 Mix on the market that make this easy; just pour the pre-mixed formula into the leaf blower’s gas tank and you should be all set.

To start the engine, the ignition switch must be set to the start position. As the starter rope is pulled, the starter engages the starter cup on the flywheel and rotates the crankshaft. The rotating crankshaft connects to the piston which moves up-and-down within the cylinder and ignition process begins. The flywheel has permanent magnets built into it, and as it rotates past the ignition coil, a magnetic field is created. The magnetic field induces electricity, allowing the ignition coil to send voltage to the spark plug.

As the piston travels down the cylinder, it exposes an intake port and pumps the gas, oil, and air from the crankcase into the cylinder. As the piston travels back up the cylinder, a vacuum is created and the gas, oil, and air is drawn through the carburetor into the crankcase. When the piston reaches the top of the cylinder, the energized spark plug will ignite the fuel and air mixture, driving the piston down, exposing an exhaust port where the spent fuel exits. A split-second later, the intake port is exposed again. Fresh fuel is drawn in and the process continues with every revolution of the crankshaft.

The exhaust from the engine will travel through the muffler and, often, a spark arrestor. The muffler reduces engine noise while the spark arrestor’s thin metal mesh prevents burning carbon deposits from exiting the engine and, potentially, starting a fire.

Engines will have a choke, primer bulb, or both to assist with starting, especially when the engine is cold. The choke will temporarily restrict air flow through the carburetor so more fuel can enter the cylinder. Likewise, a primer bulb draws additional fuel through the carburetor before the engine is started.

Top 5 reasons why the leaf blower engine is running rough

So, what could cause a leaf blower engine to run rough? Here are the five most likely causes:

  1. Restricted carburetor  –  Old or bad fuel can leave a gummy residue inside the carburetor creating a restriction. This will prevent the proper ratio of fuel and air from entering the cylinder which can cause the engine to run rough. You should always make sure you keep fresh fuel in the tank and use a fuel stabilizer to help preserve its quality. Keep in mind, you should never be using gasoline that contains more than 10% ethanol as this can damage the engine. As mentioned above, using a pre-mixed fuel and oil product might be your best choice (traditionally, these products are ethanol-free). You can try cleaning the carburetor ports with a dedicated carburetor cleaner, or WD-40, to clear out the restriction, but if the clog is particularly bad, you may need to purchase a new carburetor.
  2. Clogged fuel filter  – That gummy residue that can clog a carburetor can do the same to the fuel filter. Simply replace the filter with a new one to solve the problem. You can prevent problems with the engine by replacing the filter as part of your pre-fall leaf blower engine tune-up.
  3. Dirty air filter – By restricting the air coming into the carburetor, a dirty air filter can cause the engine to run rough as well. Yet another part that should always be replaced when tuning-up the engine or whenever the existing filter is visibly soiled.
  4. Defective spark plug – Due to carbon build-up or a weakened electrode, a spark plug will degrade over time and struggle to ignite the compressed fuel and air inside the engine’s combustion chamber. This could be the reason the engine is running rough. You can use an ignition tester to help determine the strength of the spark plug, but it’s probably easier to simply replace it with a new one; again, something that should be done during the pre-fall engine tune-up.
  5. Clogged spark arrestor – Over time, the arrestor’s thin metal mesh can become clogged with soot or other debris, which can cause the engine to run rough. You can try cleaning the arrestor with a wire brush, but you can easily, and inexpensively, replace it with a new one.

Repair Clinic has the right leaf blower parts for your model

Repair stocks all the parts you need to maintain or repair your leaf blower’s engine to ensure it will run smoothly before you need it to clear out your yard. But it’s important to identify the exact part that fits your particular model. To accomplish this, enter the leaf blower’s full model number in the Repair Clinic website search bar. You can then use the “Part Category” filter (Example: “Filter”) followed by the “Part Title” filter (Example: “Fuel Filter”) to find the specific part you need, whether it’s a spark plug, carburetor, air or fuel filter, or spark arrestor. In addition to carrying original manufacturer parts from top brands such as Craftsman, Echo, Homelite, Husqvarna, Poulan Pro, Ryobi, Toro, and Troy-bilt, Repair Clinic also has hours of “how-to” video content to assist you in replacing those parts yourself, in addition to thousands of schematics, diagrams, and articles.

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