5 Common Stihl FS 38 Problems + Troubleshooting

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The Stihl Fs 38 is the perfect level-entry trimmer in today’s market. It is lightweight and affordable yet efficient enough to tackle most of your lawn and garden trimming tasks.

However, not all are sunshine and rainbows with this unit. Many users cry out in frustration their engine won’t start or runs poorly. Some had it: the trimmer head vibrates excessively, the line breaks too often, and many more. 

Complaints here and there!

It is almost as though these problems are inevitable, or you bought them along with the trimmer.  

Below, we will look at these problems and how you can fix them yourself. 

5 Common Stihl Fs 38 Problems + Troubleshooting

1. The Engine Won’t Start

If your Stihl Fs’s engine won’t start, it has one of two problems: 

You are either using old or contaminated fuel or a clogged fuel filter. Experts also suggest it could be a faulty spark plug. 

So, instead of rushing to a nearby mechanic, you should first investigate if it is either of these problems. 

If it is, you must drain the fuel tank and refill it with fresh fuel. And ensure the fuel filter is spick and span –so is the spark plug. 

2. Engine Runs Poorly Or Stalls

When the engine doesn’t respond as it should or suddenly stops, a clogged air filter and a dirty carburetor are to blame. 

A dirty, debris, or clogged air filter prevents sufficient airflow to the engine, which might hamper its performance. 

Simply tuning the carburetor or cleaning it could also help. However, if it is damaged, you should replace it. 

3. Trimmer Head Doesn’t Spin

Some users complain their Stihl FS 38 doesn’t spin when the engine is running. It could be a result of a broken drive cable or worn-out clutch. 

If the clutch mechanism has gone rogue, you must replace it, as they are responsible for engaging and disengaging the trimmer head —same as the drive cable.

4. Trimmer Line Breaks Too Often

Frequent line breakage can be frustrating.

However, if it breaks after putting the trimmer line on, you either wore it the wrong size, cheap or low-quality lines, or your trimmer head is worn out. 

So ensure you use the correct type and diameter Stihl recommends for your FS 38.

5. The Trimmer Head Vibrates Excessively

It is normal for any fully functional unit to vibrate, but not excessively. 

If the vibrational feedback you are getting from your trimmer is too much to bear, something is wrong. 

Inspect the trimmer head for signs of wear, imbalance, or Loose Bolts, as a lousy head is often the leading cause of excessive vibration. 

Frequently Asked Questions

How Do I Change The Trimmer Line On The Fs 38?

Changing the trimmer line on the FS 38 involves Specific instructions usually found in the user manual.

What is the cutting width of the FS 38?

The cutting width of the FS 38 is typically around 15 inches (38 cm).

Changing your STIHL FS 38 trimmer is straightforward. NO twists and turns; just remove the spool, wind a new line onto it, and reattach it. 

Here is how to do it properly: 

  • Turn Off the Engine
  • Remove the spool; turn the head counterclockwise or press a release button, depending on the design.
  • Then remove the old Line.
  • Prepare and load the new line: You must cut the new trimmer line to the appropriate diameter and length. Then, load it through the holes or notches. 
  • Secure the Line by winding it onto the spool before reassembling the trimmer head.
  • Lastly, test the trimmer to see if the line is cutting effectively.

How Do I Maintain The Air Filter On The Fs 38?

Maintaining a healthy or fully efficient air filter on the Fs 38 is SO crucial. 

Not only is it a recipe for efficient combustion, but it is also a means to ensure top engine performance. 

A lousy air filter will permit the polluted incoming air to clog and restrict airflow, leading to a drop in power and efficiency –or even worse. 

I know personally from experience it also accelerates wear and tear on critical engine parts.

So, if you want to keep your air filter in tip-top shape, here is how: 

  • First, turn off the engine and disconnect the spark plug wire. 
  • Locate the Air Filter on the side of the trimmer’s engine. 
  • Unscrew to gain access. 
  • Remove and inspect the Air Filter for dirt, debris, or any sign of damage.
  • If it is excessively dirty or damaged, replace it with a filter.
  • However, if it is reusable, you can clean it. For the foam filter, clean it with warm, soapy water. Then rinse thoroughly and let it air dry. 
  • For paper filters, I’m afraid you would have to replace them whenever they get dirty.

NOTE: Cleaning or replacing the air filter should be a COLD, HARD maintenance routine, especially if you use the trimmer more often.

Can I Use The Fs 38 For Edging?


While the Fs 38’s primary function is to trim grasses and weeds, you can also use it for edging. 

You can edge by turning the trimmer head sideways to make vertical cuts that define your borders, walkways, islands, or flower beds.

Mind you, FS 38 isn’t specifically designed for edging, so you might struggle to make a fine cut. 

It takes some skill and patience, like adjusting the trimmer head to 90 degrees, positioning it vertically, maintaining a steady pace, and more.

What Safety Precautions Should I Take When Using The Fs 38?

As with any power tool, taking precautionary measures is imperative to prevent accidents and injuries. 

The STIHL FS 38 trimmer is not an exception. 

Here are some safety guidelines while using a Stihl Fs 38: 

  • Put on safety glasses to protect your eyes from flying grass, debris, and trimmer line fragments.
  • Use earplugs or earmuffs for hearing protection to reduce the risk of hearing damage from engine noise.
  • Wear a long-sleeved shirt and Pants to guard your arms and legs against flying debris that might scratch or cut you.
  • Wear sturdy footwear with good traction to protect your feet and prevent slipping. 
  • Before starting the engine, check the trimmer and ensure all nuts, bolts, or screws are properly tightened –and there are no damaged parts.
  • Clear the Work Area. Remove any visible debris, rock, or obstacle that might impede your trimmer operation, as they could become dangerous projectiles if struck by the trimmer line.
  • DO NOT touch the trimmer line with your hands while wearing protective gloves. 
  • Off the engine and replace the trimmer line when worn or damaged. 
  • Don’t turn it off immediately. First, release the throttle so the engine can die down. 


So those are the common stihl fs 38 problems users encounter. 

 Most experts call it the ‘ Fs 38 sicknesses,’ as the unit is more susceptible to suffering from them, mostly after it has passed its prime.  But remember, regular maintenance Is also key! 

A well-maintained trimmer is less likely to have these issues. 

Therefore, you should inspect your trimmer periodically, cleaning or replacing any rogue parts to ensure the unit stays in tip-top condition. 


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