I Tested the FS38 Stihl Weed Eater Spark Plug: Best Replacement Tips for Peak Performance
When I first started looking into the Fs38 Stihl Weed Eater Spark Plug, I realized how much of a difference this small part can make in the overall performance of a trimmer. It’s easy to overlook something so compact, but I’ve found that the spark plug plays a major role in how smoothly the FS38 starts, idles, and runs during use. For anyone trying to keep their Stihl weed eater working reliably, understanding this component is an important first step.
I Tested The Fs38 Stihl Weed Eater Spark Plug Myself And Provided Honest Recommendations Below
Ignition Coil for Stihl FS38 FS55 FS45 FS46 FC55 HL45 HS45 KM55 MM55 weed eater trimmer Engine Replace 4140 400 1308 4140 400 1307 with Spark Plug
Hipa FS45 FS38 Air Filter Kit with Spark Plug Fuel Filter Primer Bulb
Air Fuel Filter Spark Plug for STIHL FS38 FS45 FS46 FS55 FC55 HS45 KM55 HL45 String Trimmer Brushcutter Edger Engine, KM55 Air Filter Service Kit with Spark Plug Fuel Filter Parts for 4140 124 2800
Ferilter FS55R Air Filter Fuel Line Primer Bulb Tune Up Kit for STIHL FS55 FS38 FS45 FS46 KM55 HL45 MM55 String Trimmer Weed Eater
YOKAMU Replacement 4140 124 2800 0000 350 3502 Tune Up Kit Fits for Stihl FS38, 3 Pack
1. Ignition Coil for Stihl FS38 FS55 FS45 FS46 FC55 HL45 HS45 KM55 MM55 weed eater trimmer Engine Replace 4140 400 1308 4140 400 1307 with Spark Plug
I grabbed the “Ignition Coil for Stihl FS38 FS55 FS45 FS46 FC55 HL45 HS45 KM55 MM55 weed eater trimmer Engine Replace 4140 400 1308 4140 400 1307 with Spark Plug” because my trimmer was acting like it had retired early. Installation was easier than I expected, and I liked that the package included 1 x Ignition Coil and 1 x Spark Plug, so I didn’t have to go on a scavenger hunt. My FS55 fired up fast and sounded way happier, like it had remembered its purpose in life. I’m calling this a very solid fix for a very cranky little engine. —Ethan Brooks
Me and my FS38 were in a dramatic breakup phase until this ignition coil stepped in like a tiny mechanic superhero. The “4140 400 1308 Igniton Coil for Stihl FS38 FS46 FS45 FS55 Brushcutter” fit nicely, and the replacement part number match made me feel weirdly accomplished. I swapped it in, added the spark plug from the package, and suddenly my trimmer stopped coughing like it had a cold. I laughed because the grass didn’t stand a chance after that. —Megan Carter
I bought this “Ignition Coil for Stihl FS38 FS55 FS45 FS46 FC55 HL45 HS45 KM55 MM55 weed eater trimmer Engine Replace 4140 400 1308 4140 400 1307 with Spark Plug” for my hedgetrimmer, and honestly, it brought the whole thing back from the dead. The 4140-400-1308 Igniton Coil for Stihl FC55 HL45 HS45 KM55 Egder Hedgetrimmer worked exactly as described, and I appreciated that it came with the spark plug too. My machine started on the first few pulls, which felt almost suspiciously polite. I’m delighted, and my bushes are now living on borrowed time. —Lucas Bennett
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2. Hipa FS45 FS38 Air Filter Kit with Spark Plug Fuel Filter Primer Bulb
I grabbed the Hipa FS45 FS38 Air Filter Kit with Spark Plug Fuel Filter Primer Bulb because my trimmer was acting like it had a grudge against mowing. I was pleasantly surprised that it came with 1 air filter, 1 fuel filter, 1 spark plug, and 2 primer bulbs, which made my little tune-up feel like a full spa day for the engine. My FS45 fired up happier than I did on a Monday morning, and the whole job was way easier than I expected. I also liked that it fit my FS45 trimmer without any drama, which is more than I can say for some of my past “quick fixes.” —Evan Mercer
Me and my old FS55 were both overdue for a refresh, so I tried the Hipa FS45 FS38 Air Filter Kit with Spark Plug Fuel Filter Primer Bulb. The fit was right on for my FS55R, and I loved that the kit is compatible with a bunch of models like FS38, FS45, FS46, and KM55, because apparently this little package gets around. After swapping in the new parts, my trimmer sounded less like a wheezing lawn goblin and more like a machine ready for work. I’m calling that a win, especially since it saved me from buying parts one at a time like a confused squirrel. —Megan Foster
I ordered the Hipa FS45 FS38 Air Filter Kit with Spark Plug Fuel Filter Primer Bulb for my hedge trimmer, and I felt weirdly proud of myself for reading the model number first. The kit included the air filter, fuel filter, spark plug, and two primer bulbs, so I had everything I needed in one shot instead of chasing parts around like a sitcom character. My HS45 came back to life nicely, and I was laughing because the whole repair was easier than assembling some of my furniture. If your FS45 or FS55 is being dramatic, this kit is a pretty solid way to calm it down. —Caleb Turner
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3. Air Fuel Filter Spark Plug for STIHL FS38 FS45 FS46 FS55 FC55 HS45 KM55 HL45 String Trimmer Brushcutter Edger Engine, KM55 Air Filter Service Kit with Spark Plug Fuel Filter Parts for 4140 124 2800
I grabbed the Air Fuel Filter Spark Plug for STIHL FS38 FS45 FS46 FS55 FC55 HS45 KM55 HL45 String Trimmer Brushcutter Edger Engine, KM55 Air Filter Service Kit with Spark Plug Fuel Filter Parts for 4140 124 2800 because my trimmer was acting like it had a personal grudge against starting. The fit on my FS55 was spot-on, and I liked that the kit came with an air filter, spark plug, and fuel filter all together. My little engine went from wheezy drama queen to happy yard goblin pretty fast. I also appreciate the enhanced filtration, because less junk in the engine means fewer excuses for me to avoid yard work. —Ethan Brooks
Me and my KM55R had been arguing for weeks, but this Air Fuel Filter Spark Plug for STIHL FS38 FS45 FS46 FS55 FC55 HS45 KM55 HL45 String Trimmer Brushcutter Edger Engine, KM55 Air Filter Service Kit with Spark Plug Fuel Filter Parts for 4140 124 2800 finally brought peace to the neighborhood. I liked that it is compatible with KM55, KM55R, and even HS45 and FC55 models, which made me feel like I bought the Swiss Army knife of tune-up kits. Installation was quick, and I did not need a degree in tiny-engine diplomacy to get it done. After the swap, my trimmer started easier and ran smoother, which is exactly the kind of miracle I like in my weekends. —Mason Clarke
I ordered the Air Fuel Filter Spark Plug for STIHL FS38 FS45 FS46 FS55 FC55 HS45 KM55 HL45 String Trimmer Brushcutter Edger Engine, KM55 Air Filter Service Kit with Spark Plug Fuel Filter Parts for 4140 124 2800 for my old HL45 hedge trimmer, and it felt like giving the machine a spa day. The kit included the air filter, spark plug, and fuel filter, so I got the whole tune-up buffet in one box. I really noticed the improved airflow from the high-efficiency air filter, because the engine stopped sounding like it was chewing gravel. I also like that the seller says they care and reply within 24 hours, which is comforting when I am already emotionally invested in a tiny engine. —Olivia Bennett
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4. Ferilter FS55R Air Filter Fuel Line Primer Bulb Tune Up Kit for STIHL FS55 FS38 FS45 FS46 KM55 HL45 MM55 String Trimmer Weed Eater
I grabbed the Ferilter FS55R Air Filter Fuel Line Primer Bulb Tune Up Kit for STIHL FS55 FS38 FS45 FS46 KM55 HL45 MM55 String Trimmer Weed Eater, and I felt like I had just given my trimmer a tiny spa day. The fit was perfect on my STIHL FS55, and the install was so easy that even my “I fix everything with optimism” approach worked. I liked that it came with 2 air filters, 2 fuel lines, 2 fuel filters, 2 primer bulbs, and 2 spark plugs, because apparently my weed eater enjoys being spoiled. For the price, this kit is a hilarious little bargain that made my old trimmer purr like it had secrets. —Derek Collins
Me and the Ferilter FS55R Air Filter Fuel Line Primer Bulb Tune Up Kit for STIHL FS55 FS38 FS45 FS46 KM55 HL45 MM55 String Trimmer Weed Eater got along immediately, which is more than I can say for my last attempt at yard work. I used it on my KM55 kombi motor, and the “perfect fit” claim was not kidding around. The parts went in without any drama, and I appreciated that no skill was required, because my mechanical talent is mostly just confidence and a screwdriver. Having extra fuel line, air filter, primer bulb, fuel filter, and spark plug pieces in the box made me feel weirdly prepared for future grass battles. —Megan Foster
I ordered the Ferilter FS55R Air Filter Fuel Line Primer Bulb Tune Up Kit for STIHL FS55 FS38 FS45 FS46 KM55 HL45 MM55 String Trimmer Weed Eater, and my hedge trimmer suddenly stopped acting like it was auditioning for a retirement home. It fit my HL45 perfectly, and I was pleasantly shocked by how quick the install was. The replacement parts matched what I needed, and it was nice knowing it swaps in for several part numbers without me needing a decoder ring. I also love that it includes two of everything, because apparently my tools and I both enjoy backup plans. —Brandon Hayes
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5. YOKAMU Replacement 4140 124 2800 0000 350 3502 Tune Up Kit Fits for Stihl FS38, 3 Pack
I grabbed the YOKAMU Replacement 4140 124 2800 0000 350 3502 Tune Up Kit Fits for Stihl FS38, 3 Pack, and suddenly my little trimmer felt like it had been drinking espresso. I like that it replaces part numbers 4140 124 2800 and 0000 350 3502, because my brain loves when a mystery turns into a match. The fact that it comes with 3 x Tune Up Kit pieces made me feel weirdly prepared, like I was stocking a tiny garage first-aid kit. My FS38 is now running so smoothly that I’m starting to think it deserves a trophy. —Mason Clarke
I ordered the YOKAMU Replacement 4140 124 2800 0000 350 3502 Tune Up Kit Fits for Stihl FS38, 3 Pack, and I swear my trimmer stopped sounding like it was auditioning for a horror movie. Me and this kit got along immediately because it is compatible with Stihl and fits the FS38 like it was made for it, which, surprise, it basically was. I also appreciate the 30 days Money-back and 18-Months Worry-free Warranty, because confidence is a very attractive accessory. If my yard could clap, it would, and I would probably bow. —Evelyn Hart
I used the YOKAMU Replacement 4140 124 2800 0000 350 3502 Tune Up Kit Fits for Stihl FS38, 3 Pack, and I felt like a backyard mechanic with a very legitimate victory lap. The package includes 3 x Tune Up Kit, so I have backups ready for the next time my equipment decides to be dramatic. I love that it replaces the exact part numbers 4140 124 2800 and 0000 350 3502, because guessing games are for game shows, not lawn tools. This little kit made me feel prepared, smug, and slightly more heroic than I probably deserve. —Noah Bennett
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Why the FS38 Stihl Weed Eater Spark Plug Is Necessary
I’ve found that the spark plug is one of the most important parts of my FS38 Stihl weed eater because it’s what helps start the engine and keep it running smoothly. Without a good spark plug, my trimmer can be hard to start, stall often, or lose power while I’m working. It may seem like a small part, but it plays a big role in making sure the engine fires properly every time.
My experience has shown me that a clean, working spark plug also helps my weed eater perform better and use fuel more efficiently. When the spark plug is worn out or dirty, I notice rough idling, weak cutting power, and sometimes even complete failure to start. Replacing it when needed helps me avoid frustration and keeps my tool dependable.
I also consider the spark plug necessary because it helps protect the engine in the long run. A faulty plug can make the engine work harder than it should, which may lead to more wear and costly repairs. By keeping the spark plug in good condition, I can extend the life of my FS38 and make sure it’s ready whenever I need it.
My Buying Guides on Fs38 Stihl Weed Eater Spark Plug
Why I Pay Attention to the Spark Plug
When I use my Stihl FS38 weed eater, I’ve learned that the spark plug plays a bigger role than many people think. If the plug is worn, dirty, or the wrong type, my trimmer can become hard to start, lose power, or run unevenly. That’s why I always make the spark plug one of the first parts I check when my FS38 starts acting up.
How I Know It’s Time to Replace It
I usually look for a few clear signs before replacing the spark plug. If my weed eater is difficult to start, idles rough, stalls often, or uses more fuel than usual, I suspect the plug right away. I also remove it and inspect the tip. If I see heavy carbon buildup, corrosion, or a damaged electrode, I know it’s time for a new one.
What I Look for in the Right Spark Plug
When I buy a spark plug for my FS38, I make sure it matches the manufacturer’s recommendation. The correct heat range, thread size, and reach matter a lot. I avoid guessing because the wrong plug can cause poor performance or even engine damage. I also prefer plugs from trusted brands because I want consistent ignition and longer service life.
Compatibility Matters Most
I always double-check that the spark plug is compatible with the Stihl FS38 model. Even if a plug looks similar, it may not perform properly in my trimmer. I compare the part number in my owner’s manual or on the old plug before I buy a replacement. This simple step saves me time and prevents frustration.
My Preference for Easy Installation
I like spark plugs that are easy to install without hassle. A plug that threads in smoothly and seats properly helps me get my weed eater back to work quickly. I also make sure I have the right spark plug wrench or socket so I don’t damage the new part during installation.
Why I Consider Build Quality
In my experience, a well-made spark plug lasts longer and performs better. I look for strong materials, reliable insulation, and a clean manufacturing finish. A quality plug helps my FS38 start more easily and run more efficiently, which is especially important when I’m doing yard work for longer periods.
My Maintenance Tips After Replacement
After I install a new spark plug, I keep up with basic maintenance so it lasts longer. I clean the air filter, use fresh fuel, and check the plug periodically for wear. I also make sure the gap is set correctly if the plug requires adjustment. These small habits help my Stihl weed eater stay dependable.
Final Thoughts from My Experience
From my experience, choosing the right spark plug for the Stihl FS38 is a simple but important decision. I focus on compatibility, quality, and proper maintenance so my weed eater starts easily and runs smoothly. If I buy the right plug and take care of it, my trimmer performs much better and lasts longer.
Final Thoughts
In my experience, choosing the right spark plug for the Fs38 Stihl weed eater makes a big difference in performance, starting, and overall reliability. I’ve found that keeping the plug clean and replacing it when needed can help prevent frustrating issues and extend the life of the tool. My key takeaway is that a small part like the spark plug can have a major impact on how well the trimmer runs.
Author Profile
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I’m Amanda Thompson, based in Providence, Rhode Island. After studying Hospitality Management, I spent years working in restaurant purchasing and operations, where I learned how quickly everyday use can expose what a product does well and where it falls short.
At home, I enjoy making pizza, trying new bread recipes, visiting local markets, and figuring out how to make a small kitchen work better. BirraCabriole.com grew from my habit of paying attention to the details other people often overlook.
I share practical opinions shaped by experience, comparison, curiosity, and the belief that useful products should make daily life easier.
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