How to Start My Stihl Fs38 Weed Eater? Stihl FS38 Owner Guide

Introduction

If you’ve recently picked up a Stihl FS38 weed eater, you’re likely eager to tackle overgrown grass, weeds, and light brush around your property. But for many new owners, the first question that comes to mind is: How to Start My Stihl Fs38 Weed Eater? Unlike electric trimmers that plug in or battery-powered models that turn on with a button, the FS38 is a gas-powered 2-stroke tool that requires a specific starting sequence to run smoothly. This comprehensive owner guide walks you through every step of starting your FS38, from pre-start safety checks to troubleshooting common issues, plus essential maintenance tips to keep your trimmer running strong for years. Whether you’re a first-time gas trimmer user or just need a refresher on proper FS38 operation, this guide has everything you need to get to work quickly and safely.

• Understanding Your Stihl FS38 Weed Eater
• Pre-Start Safety Checks
• Fuel and Lubricant Preparation
• Step-by-Step Guide to Starting Your Stihl FS38
• Troubleshooting Common Starting Issues
• Post-Start Operation Best Practices
• Maintenance Tips to Extend FS38 Lifespan
• FS38 vs. Entry-Level Competitor Weed Eaters
• Frequently Asked Questions
• Conclusion

Understanding Your Stihl FS38 Weed Eater

The Stihl FS38 is a lightweight, gas-powered line trimmer designed for residential use, ideal for cutting grass, weeds, and light brush up to 1 inch thick. It’s powered by a 27cc 2-stroke engine, which means it runs on a mixture of gasoline and 2-stroke oil, unlike 4-stroke engines that have separate oil reservoirs. The FS38 features a user-friendly starting system with a primer bulb, adjustable choke, and a recoil starter, making it accessible for most users once you learn the correct sequence. It also includes a patented Easy2Start system that reduces the pulling force needed to start the engine by up to 50% compared to standard recoil starters, a feature that sets it apart from many basic gas trimmers on the market. Understanding these core components will make answering the question How to Start My Stihl Fs38 Weed Eater? far simpler, as you’ll know what each part does during the starting process.

Before you attempt to start the FS38 for the first time, take a few minutes to locate its key parts: the primer bulb (a small rubber bulb on the side of the carburetor), the choke lever (usually near the air filter cover), the throttle lock (a button on the handle that locks the throttle in the idle position), and the starter cord (the pull cord attached to the recoil starter on the top of the engine). The Easy2Start system stores energy in a built-in spring when you pull the starter cord slowly, so you don’t need to yank the cord as hard as you would with older, non-assisted models. Familiarizing yourself with these components will help you avoid common starting mistakes and reduce frustration during your first few uses.

Pre-Start Safety Checks

Safety is the first priority when operating any gas-powered power tool, and the FS38 is no exception. Skipping pre-start checks can lead to injury, tool damage, or even fire hazards. Follow these checks every time you prepare to use your trimmer to minimize risk.

Personal Protective Equipment (PPE)

Wear the following protective gear before attempting to start or operate your FS38:

• Eye protection: Safety glasses or a face shield to protect against flying debris, rocks, and trimmer line fragments.
• Hearing protection: Ear plugs or earmuffs, as gas-powered trimmers produce noise levels above 85 decibels, which can cause long-term hearing damage with prolonged exposure.
• Long pants and closed-toe shoes: To protect your legs and feet from flying debris and accidental contact with the spinning trimmer head.
• Work gloves: To improve grip on the trimmer handles and protect your hands from cuts or blisters.

If you plan to use a blade attachment instead of a trimmer line, add a hard hat and a full face shield to your PPE list to protect against kickback and broken blade fragments. Never operate the FS38 in loose, flowing clothing, as it can become caught in the moving parts of the trimmer.

Workspace and Tool Inspection

Before starting your FS38, inspect both your work area and the trimmer itself:

• Clear the area of rocks, sticks, toys, and other debris that could become dangerous projectiles when hit by the trimmer head.
• Ensure there are no bystanders, especially children or pets, within 50 feet of your work area.
• Place the trimmer on level, stable ground to prevent it from tipping while you pull the starter cord.
• Check that the trimmer head is securely attached and that the guard is properly in place to deflect debris away from the operator.
• Inspect the rubber seal around the fuel cap for cracks or wear, as a damaged seal can cause fuel leaks during operation. Replace the fuel cap if the seal is damaged to avoid fire hazards.
• Check the throttle trigger and lock to make sure they move freely and return to the idle position when released.

Fuel and Lubricant Preparation

Proper fuel and lubricant preparation is one of the most common points of confusion for new FS38 owners, and using the wrong fuel mixture is a leading cause of starting issues and irreversible engine damage. The FS38’s 2-stroke engine requires a precise mixture of unleaded gasoline and 2-stroke oil to lubricate internal components during operation, as it does not have a separate oil reservoir like a 4-stroke engine.

Correct Fuel Mix for FS38

Stihl recommends a 50:1 fuel-to-oil ratio for the FS38, meaning 50 parts gasoline to 1 part 2-stroke oil. For a standard 1-gallon gas can, this equals 2.6 ounces of Stihl-approved 2-stroke oil mixed with 1 gallon of fresh, unleaded 87-octane gasoline. Never use gasoline with more than 10% ethanol content, as ethanol can break down rubber seals in the carburetor and cause starting problems, as well as long-term engine damage. Avoid using old gas that has been stored for more than 30 days, as it can degrade and leave varnish in the carburetor that clogs fuel lines and jets.

If you don’t want to mix your own fuel, Stihl sells pre-mixed 50:1 fuel that is ethanol-free and formulated specifically for their 2-stroke tools. This is a convenient option for occasional users who don’t go through fuel quickly. When mixing fuel at home, always add oil to the gas can first, then add gasoline, and shake the can thoroughly to mix the two components evenly. Never mix fuel directly in the trimmer’s fuel tank, as this can lead to an inconsistent mix ratio that damages the engine. Always mix fuel in a well-ventilated area away from open flames or sparks, and never overfill the fuel tank – leave a small amount of space at the top to allow for fuel expansion.

Line and Blade Maintenance Basics

A worn or improperly sized trimmer line can make starting the FS38 harder and reduce cutting performance. The FS38 is designed to use 0.080-inch diameter trimmer line, which balances cutting power and ease of use for residential applications. If your line is frayed, worn down to less than 3 inches, or the wrong thickness, replace it before starting the trimmer to avoid putting unnecessary strain on the engine. If you use a blade attachment, make sure it is sharp, securely fastened, and free of nicks or damage. A dull blade will put extra strain on the engine, making starting more difficult and reducing cutting efficiency for thick weeds and light brush.

Step-by-Step Guide to Starting Your Stihl FS38

Now that you’ve completed safety checks and prepared your fuel, you’re ready to start your FS38. The starting process varies slightly depending on whether the engine is cold (hasn’t run in the last hour) or warm (has run recently). Follow the steps below for your specific situation to avoid common starting errors, and you’ll master the answer to How to Start My Stihl Fs38 Weed Eater? in no time.

Cold Start Procedure

Use this sequence when starting your FS38 for the first time of the day, or after it has been sitting for an hour or more:

1. Place the FS38 on level, stable ground. Make sure the trimmer head is not touching any surfaces, and that the engine is facing away from your body to avoid exposure to exhaust fumes.
2. Press the throttle lock button on the handle to hold the throttle in the idle position. This prevents the engine from revving too high when it starts, which can be dangerous for new operators.
3. Move the choke lever to the fully closed (cold start) position. The choke restricts airflow to the carburetor, creating a richer fuel mixture that makes starting a cold engine easier.
4. Press the primer bulb 6 to 8 times, until you see fuel visible inside the bulb. Each press pushes fuel from the tank into the carburetor, priming the engine for starting. If you don’t see fuel after 8 presses, check for clogged fuel lines or an empty fuel tank.
5. Grip the starter handle firmly with one hand, and hold the trimmer handle securely with the other. Never wrap the starter cord around your hand, as this can cause injury if the engine backfires. Pull the starter cord slowly until you feel resistance, then pull it quickly and firmly. Repeat this 3 to 4 times. You may hear the engine sputter or attempt to start, but it will likely die after a few seconds at this stage.
6. Once the engine sputters, move the choke lever to the half-open position. This gradually introduces more air into the fuel mixture as the engine warms up.
7. Pull the starter cord 1 to 2 more times. The engine should start running steadily at idle speed.
8. Let the engine run at idle for 30 seconds to warm up, then slowly move the choke lever to the fully open position. Adjust the throttle as needed to keep the engine running smoothly. Your FS38 is now ready for use.

Warm Start Procedure

If you’ve been using the FS38 and need to restart it after a short break (less than an hour), use this faster sequence:

1. Place the trimmer on level ground, and engage the throttle lock as you would for a cold start.
2. Move the choke lever to the half-open position, or leave it fully open if the engine is still warm to the touch. Using a fully closed choke on a warm engine will cause it to flood with fuel, making starting impossible.
3. Press the primer bulb 2 to 3 times to add a small amount of fuel to the carburetor.
4. Pull the starter cord once or twice firmly. The engine should start immediately without sputtering.
5. Let the engine run at idle for 10 to 15 seconds before resuming full-speed operation, to allow oil to circulate through the engine.

If you’re still asking How to Start My Stihl Fs38 Weed Eater? after following these steps, don’t worry – starting a gas trimmer takes practice, especially if you’re new to 2-stroke engines. Most users master the sequence after 2 or 3 uses, and the Easy2Start system will make pulling the starter cord much easier once you get the hang of it.

Troubleshooting Common Starting Issues

Even experienced FS38 owners occasionally run into starting problems, especially if the trimmer has been stored for long periods or used with incorrect fuel. Below are the most common issues and their solutions to get your trimmer running again quickly without needing professional repair.

If you’ve tried all of these solutions and your FS38 still won’t start, consult your owner’s manual or contact a Stihl authorized service center for professional assistance. Attempting to repair internal engine components without proper training can cause further damage and void your 2-year limited warranty. If you’re having trouble starting the FS38 in cold weather (below 40°F), move the choke to the fully closed position and press the primer bulb an extra 2 to 3 times to add more fuel to the carburetor. You can also store the trimmer in a warm garage before use to make starting easier.

Post-Start Operation Best Practices

Once your FS38 is running, follow these best practices to operate it safely and efficiently, and to avoid unnecessary wear on the engine that could lead to starting issues down the line:

• Let the engine run at idle for 30 seconds (cold start) or 10 seconds (warm start) before engaging the throttle. This allows oil to circulate through all internal engine components, reducing wear on the piston and cylinder.
• Never run the engine at full throttle immediately after starting, as this can damage the piston and cylinder seals before the engine is fully warmed up.
• Check for fuel leaks around the tank, fuel lines, and carburetor while the engine is running. If you smell strong gasoline fumes or see visible leaks, turn off the engine immediately and address the issue before continuing to use the trimmer.
• Adjust the handle height to a comfortable position before beginning work, to reduce strain on your arms and back during extended use.
• Engage the trimmer head slowly when beginning to cut, to avoid jerking the trimmer or damaging the line.
• If the engine stalls when you first release the throttle lock, it may be idling too low. Adjust the idle speed screw on the side of the carburetor clockwise in small increments until the engine runs smoothly at idle without stalling.

Maintenance Tips to Extend FS38 Lifespan

Regular maintenance is the key to keeping your FS38 running reliably for years, and will also make starting easier over time by preventing clogs and wear on internal components. Follow these simple maintenance tasks after every 5 to 10 hours of use, or at least once per season:

• Clean the air filter: Remove the air filter cover and wash the foam filter in warm, soapy water. Let it dry completely before reinserting it. A clogged air filter restricts airflow, making starting harder and reducing engine power by up to 25%.
• Inspect and replace the spark plug: Remove the spark plug and check for fouling, wear, or carbon buildup. Clean it with a wire brush, or replace it entirely every 6 to 12 months to ensure consistent starting performance. Stihl recommends using only OEM replacement spark plugs to avoid compatibility issues.
• Clean the trimmer head: Remove built-up grass, weeds, and debris from the trimmer head after each use. Wrapped debris can put extra strain on the engine and make starting more difficult, as well as reduce cutting efficiency.
• Drain fuel for long-term storage: If you won’t be using the FS38 for more than 30 days, drain all fuel from the tank and carburetor to prevent varnish buildup. Run the engine until it stalls to clear fuel from the lines. If you store the trimmer for more than 6 months, add a fuel stabilizer to the fuel tank before draining it, to further prevent varnish buildup.
• Sharpen or replace the blade (if used): A sharp blade cuts more efficiently, reducing strain on the engine and making starting easier. Sharpen the blade after every 5 to 10 hours of use, or replace it if it is chipped or worn.
• Lubricate internal components for storage: Before long-term storage, remove the spark plug and add a small amount of 2-stroke oil into the cylinder, then pull the starter cord a few times to coat the piston and cylinder walls with oil. This prevents rust and corrosion during storage.
• Store in a dry, cool place: Keep the FS38 in a garage or shed away from direct sunlight, moisture, and extreme temperatures to prevent rust and damage to plastic and rubber components.

FS38 vs. Entry-Level Competitor Weed Eaters

If you’re comparing the Stihl FS38 to other entry-level gas trimmers, you may be wondering how its starting system and overall performance stack up. The table below compares key features of the FS38 to two popular competitors: the Ryobi 25cc Gas Trimmer and the Craftsman 26cc Gas Trimmer.

As the table shows, the FS38 has a slightly larger engine and a more user-friendly starting system than its main competitors, which explains why it is a top choice for homeowners who want reliable, easy-to-use performance. The 50:1 fuel mix ratio also means you use less oil per gallon of gas, which can save you money on operating costs over time. While the FS38 is more expensive than the Ryobi and Craftsman models, its larger engine, easier starting system, and higher build quality make it a better long-term investment for frequent users who want a tool that will last for years with proper maintenance.

Frequently Asked Questions

Why does my Stihl FS38 only run for a few seconds before dying?

This is one of the most common starting issues for FS38 owners, and it is almost always caused by one of three things: a clogged air filter, an incorrectly set choke, or a dirty carburetor. Start by cleaning or replacing the air filter, then verify the choke is in the correct position for a warm or cold start. If the problem persists, check the spark plug for fouling, as a dirty plug can cause the engine to die shortly after starting. If cleaning the spark plug doesn’t fix the issue, you may need to clean the carburetor jets to remove built-up varnish from old fuel.

Can I use pre-mixed fuel in my FS38?

Yes, pre-mixed 50:1 2-stroke fuel that is ethanol-free is fully compatible with the Stihl FS38, and is a great option for users who don’t want to mix their own fuel. Avoid pre-mixed fuel with ethanol content higher than 10%, as this can damage the carburetor and internal engine seals over time, leading to starting issues and reduced performance.

How often should I replace the spark plug on my FS38?

Stihl recommends replacing the spark plug every 6 to 12 months, or after every 100 hours of use, whichever comes first. If you notice hard starting, rough idling, or reduced power, check the spark plug first, as a fouled plug is a common cause of these issues. Always use a Stihl OEM spark plug or a compatible replacement from a reputable manufacturer to avoid performance problems.

Is the FS38 suitable for thick weeds and small saplings?

The FS38 is designed for grass, weeds, and light brush up to 1 inch thick. For thicker saplings or dense, woody brush, you will need to upgrade to a larger Stihl model like the FS56 or use a blade attachment rated for your trimmer. Using the FS38 for tasks beyond its designed capacity can put excessive strain on the engine, leading to premature wear and reduced lifespan, as well as making starting more difficult over time.

Can I adjust the throttle sensitivity on my FS38?

Yes, the FS38 has an adjustable throttle screw on the side of the carburetor that allows you to fine-tune the idle speed and throttle response. Adjustments should only be made with the engine running and after the trimmer is fully warmed up. If you are unsure how to make these adjustments, consult your owner’s manual or take the trimmer to a Stihl authorized service center to avoid damaging the engine or creating a safety hazard.

Conclusion

Mastering the answer to How to Start My Stihl Fs38 Weed Eater? is easier than you might think, especially once you understand the core components of the tool and follow the correct starting sequence for cold or warm engines. By prioritizing pre-start safety checks, using the proper 50:1 fuel mix, and performing regular maintenance, you’ll keep your FS38 running reliably for years, with minimal starting issues. If you do run into problems, refer to the troubleshooting section above to identify and fix common issues quickly, rather than waiting for professional repair. With a little practice, you’ll be able to start your FS38 in just a few seconds, and tackle even the toughest overgrown areas around your property with ease.