Top 10 Causes Of Starting, Stalling & Dying In A STIHL String Trimmer!

It’s difficult to complete all of your yard chores when your string trimmer won’t start. In order to get your trimmer operating again, I have compiled a list of common causes of its death.

Inadequate air, fuel, or spark can cause a STIHL string trimmer to start, stall, and die. This can occur, for example, if the air filter is clogged, the choke is set incorrectly, the spark arrestor is plugged, the fuel line is clogged, the fuel filter is clogged, the carburetor is dirty, the fuel tank vent is blocked, or the spark plug is fouled.

String Strimmer
String Strimmer

Causes of a String Trimmer’s Failure to Start and Maintain a Charge on a STIHL Model

  • Improper adjustment of the choke
  • Aspiration filter obstruction
  • A blocked air conditioner
  • Incorrect fuel blends or stale fuel could cause an explosion.
  • Because of a clogged fuel filter
  • Due to a clogged fuel line
  • Faulty fuel-tank vent
  • Unclean carburetor
  • A spark plug that is either dirty or no longer functioning.
  • Filled spark arrester screen

10 Causes of a Dead STIHL String Trimmer

A STIHL String Trimmer With the Wrong Choke Setting

A STIHL string trimmer has a choke knob. This is how the airflow is adjusted by opening and closing the choke.

Starting a cold engine requires more gasoline and less air, hence the throttle must be in the on/closed position.

Once the engine has warmed up, the choke knob should be turned to the open position to ensure that the engine receives enough air to keep running. The STIHL trimmer will splutter and die if the choke isn’t adjusted.

Overloaded STIHL String Trimmer’s Air Filter

When operating a STIHL string trimmer, a great deal of dirt and other particles are released into the air. To prevent this debris from getting into the carburetor throat and damaging the engine, an air filter is installed.

If the air filter isn’t maintained properly by being cleaned or replaced on a regular basis, it might become so clogged with dirt that not enough air can move through it.

Due to a lack of oxygen, the engine will shut off.When it comes to maintaining your air conditioner, I suggest checking the filter once a month and changing it yearly. If your filter is extremely soiled, torn, or soaked through, you should get a new one. You should take it off and clean it when it gets soiled.

Instructions for Servicing the Air Filter on Your STIHL String Trimmer

  • To prevent grime from entering the carburetor, close the choke.
  • It’s time to take off the protective covering of the air filter.
  • The area around the air filter must be cleaned.
  • Get rid of the air filter.
  • The dirt can be dislodged from the filter by tapping it against your palm. If you need more air, get a compressor. If the filter appears to be severely soiled or broken, a new one should be installed.
  • Put in the filter for the air conditioner.
  • Replace the filter cover.

String Trimmer from STIHL with Blocked Cooling System

When the engine gets too hot, it can shut down. The powerplant of a STIHL string trimmer is cooled by air.

Please hold off on starting the engine until it has cooled down. Ensure enough airflow by inspecting the cooling system and clearing any debris from the air intakes, the cylinder covers, the outside of the cylinders, and the cylinder fins.

Keep the trimmer clean so that cold air can reach the motor.

Reusing Fuel in a STIHL String Trimmer

The vast majority of STIHL string trimmers are powered by 2-cycle engines, although a select handful are powered by 4-MIX engines. Both types of engines function best when fed a 50:1 blend of gas and 2-cycle oil.

Using the incorrect fuel or a fuel mixture might damage an engine. Straight gas should never be used in a STIHL trimmer. As a result of the absence of lubrication, the engine would surely seize.

Long-term storage of stale gas in a string trimmer can also corrode the fuel system.

In order to properly fuel STIHL string trimmers, a 50:1 mixture of gasoline and oil is required. Combine premium unleaded two-cycle oil that is certified to both ISO-L-EGD and JASO M345 FD with unleaded gasoline that has a minimal octane rating of 89 and a high ethanol concentration of 10%.

Never put more than 10% ethanol in your gas tank. The best option is fuel without ethanol, but it will cost you more.

Any Ace Hardware or authorized STIHL dealer should carry STIHL 2-cycle engine oil. Two-cycle oil, such as STIHL High Performance or STIHL HP Ultra, is what the company suggests.

Because after just 30 days, gas can start degrading. New gasoline can be preserved for a longer period of time without deteriorating if a fuel stabilizer is added to it. Running on old gas can cause fuel problems, but using a fuel stabilizer can help reduce the severity of such problems.

Remember that some 2-cycle oils also function as a fuel stabilizer. If you purchase oil that claims to contain a stabilizer, be sure to check the expiration date to determine how long the stabilizer actually works.

When using a fuel stabilizer, STIHL suggests using the fuel within 30 days of purchasing it and no later than 60 days.

More about: STIHL String Trimmers Use This Type of Gas and Oil Fuel Mix.

A STIHL String Trimmer with a Clogged Fuel Filter

There is a little filter within the gas tank that prevents debris and dirt from entering the fuel system. It is connected to the fuel line’s terminus. If the filter is not changed frequently enough, it can become clogged.

If your gasoline filter becomes clogged, it can prevent your STIHL from starting. The fuel filter should be replaced once a year, or more frequently if necessary. If you’re using it professionally, you might need to replace it every three months.

To change the fuel filter on a STIHL:

  • Before removing the gasoline cap, give the area around it a quick wipe to remove any dust or debris that could otherwise enter the tank with the cap.
  • The filter can be accessed by you. One can “fish” the filter out of the aquarium by using a clean, bent wire.
  • Take the gasoline line apart and get rid of the old filter. The line holding ring must be kept on the filter at all times.
  • Replace the old fuel filter with a new one and use the retaining ring to connect the fuel line to the filter.
  • Return the filter to its original location inside the fuel tank, then replace the cap.

A STIHL String Trimmer With Clogged Fuel Lines

Old fuel can leave deposits in the fuel lines that can eventually pile up and restrict the fuel’s flow.

If you discover a clogged gasoline line, you can attempt to clear the obstruction by removing the line and spraying carburetor cleaning on the clog, followed by compressed air.

A new fuel line should be installed if the old one is dry, broken, or otherwise damaged.

String Trimmer by STIHL with Blocked Fuel Tank Vent

The STIHL gas tank must have some sort of opening for ventilation. If the opening is blocked, a vacuum will develop inside the tank. Due to the lack of pressure, the gasoline supply cannot reach the carburetor.

It’s conceivable that the trimmer will get bogged down and run roughly during use. It could possibly simply shut down due to running out of gasoline.

In the absence of a clogged fuel filter, a functioning carburetor, and obstructions in the fuel lines, a clogged fuel vent may be to blame for the absence of gasoline supply.

Put your STIHL string trimmer on a flat surface to see if it works properly. Always be sure you’re in a room with plenty of fresh air.

Before turning on the trimmer, make sure the fuel cap is loose enough to let air into the tank. Stop any fuel leaks immediately. Reinstall the fuel cap while the trimmer is still operating, after it has started and is running.

Keep it running for a while longer to see if you can trigger the issue. The gasoline tank vent is probably clogged if the car sputters and quits with the cap on but starts right up when you take it off.

Put in a replacement vent if this one is broken.

A STIHL string trimmer with a dirty carburetor.

The carburetor controls the ratio of fuel to air before it enters the cylinder for combustion. Carburetor problems prevent the engine from receiving the fuel it needs to work.

When varnish builds up in the passages of a STIHL carburetor, the engine may no longer run on old gasoline.

The crusty layer this fuel leaves behind might prevent the carburetor bowl from filling with fuel and cause internal parts to stick.

You might try cleaning the carburetor to get rid of the deposits and clean the components if it stops working. To ensure proper reassembly, it is important to document each step of the disassembly process with photographs.

After removing the carburetor and cleaning it, if it still doesn’t work, you may need to repair it or get a new one.

It may be more cost-effective to buy a new STIHL string trimmer rather than replace the carburetor if the two are comparably priced. The decision to replace an old string trimmer depends on its age, cost, and functionality.

A STIHL String Trimmer with a Faulty or Unclean Spark Plug

A dead engine could be the result of a spark plug that is too old or too unclean to create a steady spark. Check the condition of the spark plug by removing it.

Whether the tip is black, the electrode is burned, or the porcelain is fractured, it’s time to swap out the spark plug. A wire brush might help if there is only a light coating of dirt on it.

I would replace the spark plug if I thought it was the source of the problem. The trimmer’s performance is heavily dependent on the spark plug, a low-cost maintenance element.

Verify that the electrode gap satisfies STIHL’s guidelines. Assuming the spark plug is functional and the gap is adjusted appropriately, put it back in. When you’re done fixing everything, then you can connect the wire to the spark plug.

Plugged STIHL String Trimmer Spark Arrestor

Once the spark arrestor screens is coated in soot, it will no longer allow exhaust air to pass through. String trimmers are susceptible to clogging and malfunction due to debris on the screen.

A little metal screen, the spark arrestor screen, is attached to the muffler to prevent sparks from escaping. In many jurisdictions, this is obligatory to prevent burns and fires from being caused by hot exhaust material erupting from the trimmer.

How to Clear a STIHL Spark Arrestor Screen

  • A spark plug wire must be disconnected.
  • Make sure you give the muffler some time to cool down.
  • Take off the cover of the spark arrestor screen, together with any gaskets and the spark arrestor screen from the muffler.
  • Using a wire brush or industrial solvent, wipe the screen clean.
  • If the screen is cracked, has a hole in it, or cannot be cleaned thoroughly, it should be replaced.

If you still have issues after looking for the spark arrestor screen, or if you purchased a used STIHL string trimmer, talk to your local STIHL dealer.