Gas-Powered Leaf Blower Starting Then Stalling? 5 Likely Causes

Home » Gas-Powered Leaf Blower Starting Then Stalling? 5 Likely Causes

As identified right in its descriptive name, a leaf blower is usually associated with fall clean-up as the fastest way to clear those fallen leaves from your lawn or driveway. But this convenient piece of outdoor power equipment can really be used anytime yard debris needs to be rounded-up and disposed of, to clean out gutters, or to help dry wet surfaces. You can even use it to clear snow if the blower is powerful enough.

While many homeowners rely on electric or battery-powered models, those who want more power and greater efficiency will use a gas-powered hand-held or backpack blower to do the job. Of course, these models come with their own set of challenges, including the potential for the engine to stall out unexpectedly once you get the leaf blower started. In this article, Repair Clinic will examine how a gas-powered leaf blower’s engine functions and the five probable reasons why that engine might stall out after it starts.

A gas-powered leaf blower engine primer

A gas-powered leaf blower may use a four-cycle engine or a two-cycle engine, depending on the model. Backpack leaf blowers, which are generally the most powerful, will often use four-cycle engines. Hand-held models, which need to be more lightweight by design, will use a two-cycle engine. The main difference between the two types of engines is that the four-cycle engine requires two revolutions of the crankshaft and piston to draw the fuel and air into the cylinder, ignite it, then exhaust the combustion gases whereas a two-cycle engine requires just one revolution to do the same thing.

Using the right engine oil

While a four-cycle engine normally relies on SAE 30-weight oil poured into its own sump for proper lubrication, a two-cycle engine requires the oil to be mixed with the gas in the fuel tank for the engine to operate properly. Operators should be aware that 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 makes this easy; just pour the pre-mixed formula into the leaf blower’s gas tank and you should be all set.

How two-cycle and four-cycle leaf blower engines operate

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 the 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.

On both four-cycle and two-cycle engines, fuel and air will enter the cylinder where it is compressed by the piston as it travels to the top of the cylinder. The spark plug fires and ignites the fuel and air mixture. This drives the piston back down through the cylinder to rotate the crankshaft. The momentum of the spinning flywheel provides enough force to push the piston back up where the spark plug will again ignite newly drawn-in fuel and air. This process continues with every revolution of the crankshaft until the engine is shut off.

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.

Exhausting the spent fuel

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 will stop burning carbon deposits from exiting the engine. This helps prevent injury and the potentiality of setting any dry leaves or grass on fire.

Troubleshooting a leaf blower engine that keeps stalling

If your gas-powered leaf blower’s engine keeps stalling, Repair Clinic has five potential causes you can troubleshoot:

  1. Clogged spark arrestor  – Over time, the arrestor’s metal mesh can become clogged with soot or other debris, which can cause the engine to stall. You can try cleaning the arrestor with a wire brush, but you can easily, and inexpensively, replace it with a new one.
  • 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 stall after running for a few minutes. 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, if your leaf blower is powered by a two-cycle engine, you should consider using a pre-mixed fuel and oil product (traditionally, these products are ethanol-free) to ensure you’re getting the right fuel and oil balance. 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.
  • Clogged fuel filter – That gummy residue that can clog a carburetor can do the same to the fuel filter. Cleaning out a fuel filter is rarely successful and will probably just damage the component. It is far better to simply replace the old, clogged filter with a new one to resolve the issue. You can prevent stalling problems with the engine by replacing the filter as part of your annual leaf blower engine tune-up.  
  • Dirty air filter – By restricting the air coming into the carburetor, a dirty air filter can cause the engine to stall as well. Yet another part that should always be replaced when tuning-up the engine or whenever the existing filter is visibly soiled.
  • Obstructed fuel cap – As fuel is consumed, the level is the fuel tank lowers. To avoid creating a vacuum, many fuel caps will have a small vent hole or holes to allow air into the tank. If the vent holes are obstructed by build-up or debris, the air will not be able to enter the tank which can cause the engine to stall. If this is happening to you, try loosening the fuel cap slightly, then start the engine. If the engine runs normally, it’s likely the vent hole or holes are blocked, and the fuel cap should be replaced with a new one.

Keeping your leaf blower engine well-maintained

Replacing the air and fuel filters on your gas-powered leaf blower before you need to use the equipment is the kind of preventative maintenance that can keep the blower’s engine from stalling. Repair’s “Videos & Articles” library is filled with instructional maintenance tips, including step-by-step procedural videos showing how to replace the fuel filter on a Homelite hand-held leaf blower (model UT09526) and how to install a new carburetor on an Echo back-pack leaf blower (model PB580T).

Find genuine manufacturer’s parts for your leaf blower at Repair Clinic

When installing a new air filter, fuel filter, spark arrestor, or carburetor, it’s vital you use the correct genuine manufacturer parts that match your model. As your repair partner, Repair Clinic will help you identify the right parts for your leaf blower. All you need to do is enter the leaf blower’s full model number in Repair Clinic’s “Search Parts Online & Get Answers” search bar to see a comprehensive list of compatible OEM parts from top brands such as Craftsman, Echo, Homelite, Husqvarna, Poulan Pro, Ryobi, Toro, and Troy-Bilt. Having the right part on hand, in addition to Repair Clinic’s free repair help content, will make fixing your leaf blower a breeze!

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