A leaf blower is a great piece of equipment to have on hand to make your leave removal task a little easier. It’s also a great tool to clean the patio or deck; remove debris and dry a lawn mower, or even remove a light dusting of snow. You may not realize how valuable a leaf blower is until it stops working.
A STIHL leaf blower starts and then dies because of old fuel, a plugged air filter, a clogged fuel tank vent, a plugged fuel filter, clogged fuel lines, a dirty carburetor, or a faulty ignition module.
It can also stop running when the spark arrestor is clogged, the cooling system is plugged or the choke isn’t set in the correct position.
Always take safety precautions before working on your leaf blower. This includes removing the spark plug wire, waiting for the engine to cool, and waiting for all parts to stop moving.
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Follow all safety instructions provided in your equipment operator’s manual before diagnosing, repairing, or operating. Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.
Reasons Your STIHL Leaf Blower Starts Then Dies
Incorrect Choke Setting
The choke is used to start a cold engine. It restricts the amount of air so there is a higher concentration of fuel being used.
Once the engine gets warm, the choke must be adjusted to the off position so the blower continues to run. If it isn’t adjusted, the STIHL blower will end up dying because it isn’t getting good airflow.
Plugged Air Filter
Another airflow issue to check on your STIHL blower is a plugged air filter. An air filter is installed to keep dirt from entering the carburetor choke and wearing the engine.
Operating a leaf blower creates a dirty environment with dust and debris thrown into the air. The filter must be kept clean so your leaf blower continues to run without bogging down or quitting due to a lack of air.
I recommend replacing the air filter annually if you use your blower like the average homeowner and checking it several times throughout the season to clean it.
If you are using the filter in very dirty conditions, for commercial purposes, or more than the average homeowner, check, clean, and replace the filter more often.
Clean a STIHL leaf blower air filter:
You may have a round air filter like the image above or your air filter may be flat and square shaped. These cleaning instructions apply to both types.
- Close the choke so dirt doesn’t fall into the carburetor throat.
- Remove the air filter cover and remove the air filter.
- Wipe out any dirt or debris remaining in the air filter cover or housing.
- Tap the filter against a solid surface or your hand to knock the dirt out of the filter.
- Install the clean filter. (Replace a very dirty filter or one that is damaged with a new air filter).
- Reattach the air filter cover.
Old or Bad Fuel Causes
It’s best to use fresh fuel to keep your STIHL blower running at its best. When fuel ages, it will leave behind a gummy substance that can restrict fuel flow and cause your blower to sputter and die.
Because gas can begin to go bad as quickly as 30 days after purchase, consume the fuel within this time or add a fuel stabilizer to make it last a little longer.
Use a gas with a minimum octane rating of 89 and an ethanol content no higher than 10%. Always choose a low ethanol content or ethanol-free fuel as ethanol has a negative effect on a STIHL’s small engine.
STIHL 2-cycle leaf blowers and STIHL 4-Mix technology leaf blowers require a fuel mixture of gasoline and premium 2-cycle engine oil. Gas and oil are mixed at a ratio of 50:1.
Read more about choosing the right fuel and mixing it in “This is the Type of Gas and Oil STIHL Leaf Blowers Use“.
Use a fuel stabilizer in your STIHL leaf blower
When you find the gas in your leaf blower is old, empty the fuel tank and fill it with fresh fuel with an added fuel stabilizer like Sea Foam Motor Treatment. Sea Foam helps clean the fuel system and engine while reducing moisture.
Keep in mind some 2-cycle oils include a fuel stabilizer. Even though the bottle of oil states it includes a stabilizer, read the fine print to see how long the additive will keep the fuel stable.
If it doesn’t state a timeframe, don’t assume it will work longer than 30 days.
STIHL recommends using their two-cycle oil STIHL High Performance or STIHL HP Ultra and consuming fuel within 30 days and not longer than 60 days.
This will help you get the best performance from your fuel and minimize fuel restrictions causing the blower to run sluggishly.
Plugged Fuel Filter
Old dirty fuel can clog the fuel filter keeping a good flow of fuel from running through the leaf blower. You will find the fuel filter inside the fuel tank. It’s attached to the end of the fuel line.
When it becomes plugged, your STIHL blower won’t get sufficient fuel. To avoid this happening to you, replace your fuel filter annually and run clean fuel through your blower.
If you are using your blower for commercial purposes or more than the average homeowner, you should change the fuel filter more frequently.
Replace a STIHL leaf blower fuel filter:
- Wipe around the fuel cap to remove dirt and debris so they don’t fall into the tank.
- Remove the cap.
- Pull the fuel filter out of the fuel tank. A clean bent wire works well to retrieve the filter.
- Once the filter is out of the tank, remove it from the fuel line. Don’t let go of the fuel line and allow it to drop back inside the fuel tank. Using needle nose pliers to hold the fuel line can help grip the fuel line tighter so it doesn’t slip out of your hand and fall back inside the fuel tank.
- Attach the new fuel filter by inserting the male end into the fuel line and making sure it is securely attached.
- Place the fuel filter back inside the fuel tank.
- Install the fuel cap.
Clogged Fuel Line
Old fuel can leave behind gummy deposits that may restrict fuel flow through the fuel lines. When this happens, remove the fuel line and install a new STIHL fuel line.
If the fuel line appears in good condition, you can attempt to clean out the line using carburetor cleaner to loosen the clog and compressed air to remove the clog.
When inspecting your fuel lines you find them dry and cracked, you should replace the line before it begins leaking or drawing air into the line from a puncture.
Plugged Fuel Tank Vent
The fuel tank must be able to vent. Without a vent to allow air to pass through it and into the tank, the tank will form a vacuum. It won’t allow fuel to leave the fuel tank.
If you are not getting sufficient fuel to the carburetor and don’t have a clog in the fuel line or filter, you need to check the vent.
If your STIHL blower died and doesn’t start, confirm the fuel tank vent is clogged by placing your leaf blower on a level surface. Loosen or remove the fuel cap to allow air into the tank and start the blower.
If the blower starts and runs fine, tighten the fuel cap onto the fuel tank. Run your leaf blower for a little while to see if your problem returns and the leaf blower shuts off.
You may have a plugged fuel vent if the blower dies and the fuel cap needs to be loosened or removed to start it again.
Replace a clogged fuel tank vent. You will find the tank vent located on the fuel tank.
Dirty Carburetor Causes a STIHL Leaf Blower to Start Then Die
The carburetor mixes the correct proportion of air and fuel required for your leaf blower to start and continue to run.
The passageways can become clogged and the small components can fail to function correctly which can be the reason the blower stops running.
Old fuel usually plays a part in the carburetor no longer working. You may be able to clean or rebuild the carburetor to get it working again. You will have to replace the carburetor if this doesn’t work.
Plugged Cooling System Causes a STIHL Leaf Blower to Start Then Die
The engine must be kept cool so it doesn’t overheat. To help cool the STIHL engine, you must remove grass, dirt, and debris that block the air intake and cooling fins.
To do this, first, remove the spark plug and wait for the engine to cool. Remove the engine cover and remove debris from the cover and around the outside of the cylinder.
Clean the cylinder fins and reinstall the engine cover. Continue cleaning the blower to make sure cool air can circulate around the engine.
On a STIHL backpack leaf blower, remove any debris from the grill between the backpack and blower housing. On a handheld blower, remove the debris from the intake and discharge grill.
Carburetor Needs Adjustment on a Stihl Leaf Blower
STIHL sets the carburetor settings at the factory to ensure the blower is getting the fuel-to-air mixture to run at its best. The quality of fuel and high altitudes can affect the carburetor and the settings may need to be adjusted to get a good performance from the engine.
You will find 3 carburetor adjustment screws on your STIHL leaf blower. The screws are labeled “H” for high speed, “LA” for idle speed, and “L” for low speed.
If you are unsure your leaf blower is set at its original factory settings, you may be able to find this information in your STIHL operator’s manual. If they are not located in your manual, bring your leaf blower to your local STIHL dealer for assistance.
STIHL does have some limits to the adjustments you can perform to the carburetor. Many models require a special tool STIHL-certified mechanics have on hand to adjust the carburetor.
If you continue to have problems with the carburetor, bring your leaf blower to your local STIHL dealer for assistance.
Here are instructions for setting the adjustment screws to the standard setting for common STIHL handheld blowers BG 50, BG 55, BG 65 and BG 85:
BG50, BG55, BG65, BG85 Handheld Leaf Blowers
Standard Carburetor Setting:
Begin the carburetor adjustment by placing the “H” and “L” adjustment screws at their original standard settings.
- High-Speed Screw “H”: Turn the screw counterclockwise until it stops. Do not force it past the natural stop which should be no more than 3/4 turn).
- Low-Speed Screw “L”: Turn the screw clockwise until it stops. Then, turn it counterclockwise a 3/4 turn.
Adjust “LA” idle screw:
Next, with the engine warm and while the leaf blower idles, you may need to adjust the idle screw. This is often needed when an adjustment is made to the low-speed screw. The blower engine should run smoothly.
If your leaf blower dies at idle, turn the idle screw clockwise until it runs smoothly. Then turn the screw counterclockwise 1/4 turn.
Adjust “L” low-speed screw if needed:
Let the leaf blower idle. Adjust the low-speed screw slowly until you find the “sweet spot” where it runs smooth and not sluggish if needed.
Slowly turn the screw counterclockwise if it is running too lean (not getting enough fuel) or clockwise if it is running too rich (getting too much fuel).
Adjust “H” high-speed screw if needed:
Next, fine-tune the “H” screw to get a good smooth RPM at full throttle by slowly turning the adjustment screw clockwise if needed. Don’t over-adjust and allow the RPMs to increase too much or you will damage the engine.
Bad Spark Plug on a Stihl Leaf Blower
A dirty or broken spark plug won’t provide the consistent spark needed to run the leaf blower. It may provide intermittent spark causing the saw to lose power and possibly die.
Inspect the condition of the spark plug tip. If it is very dark in color and has a broke porcelain or burnt electrode, the spark plug must be replaced.
You can try to clean the spark plug with a wire brush and reuse it if it’s just a little dirty. I prefer to just replace it. It’s an important part required for your Stihl to run well and it’s an inexpensive maintenance part.
Make sure the spark plug gap is correct and the spark plug wire is securely attached. These two items can also cause the leaf blower to shut down.
Plugged Spark Arrestor Causes a STIHL Leaf Blower to Start Then Die
There is a small metal screen that keeps hot exhaust material from shooting out of the leaf blower and causing injury or starting a fire. This small screen on your muffler will become plugged with a buildup of carbon that will affect how the engine runs.
Disconnect the spark plug wire. Allow the engine to cool. Access the STIHL blower’s spark arrestor screen and carefully remove it from the blower. Clean it with a metal brush.
If the screen isn’t able to be sufficiently cleaned or you find it is damaged or has a hole in it, replace it with a new spark arrestor screen.
To minimize carbon building up on the spark arrestor quickly, make sure you periodically run your blower at full throttle. Letting your blower idle or run at low speeds for a long time will contribute to a buildup of carbon.
Faulty Ignition Coil Module on a Stihl Leaf Blower
After you have confirmed the spark plug is in good condition, check the ignition module to make sure it is functioning correctly. The module provides the electrical current to the spark plug to form a spark that ignites the fuel to start and keep your blower running.
When the coil gets hot, the windings on the coil can separate and short out. This will cause your Stihl leaf blower to lose power, run sluggishly, or stop running when there is an intermittent spark.
A bad ignition module will not be able to provide sufficient voltage to the spark plug.
Compression Problem with a Stihl Leaf Blower
While pulling the starter recoil rope, you may notice a loss of compression. When the compression is low on a Stihl leaf blower, it will fail to have enough pressure which can cause it to quit running. This can be the result of worn crankshaft seals, worn piston rings, or damage to the piston.
I recommend taking your leaf blower to a small engine mechanic or your Stihl dealership for testing and making necessary repairs.