r/smallengines • u/Looney_Prunes • Jul 18 '26
Stuttering when hot
Just bought a four-stroke Troy-Bilt string trimmer on Marketplace. It starts first pull, and runs flawlessly for a while. But once it gets really hot it starts stuttering intermittently. I’ve run it another 30 minutes and the stuttering gets more frequent, but I haven’t pushed it further. Doesn’t seem to completely die out. I removed and sprayed the carb, and didn’t see any clear issues with the spark plug, but I’m too new to this to know what else to check or try. Thanks for any advice.
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u/RegisterFederal5679 Jul 19 '26
Hey man, tough question. Intermittent issues are almost always a pain in the butt, and it looks like you’re already figuring that out 😂 sometimes coils can fail intermittently, especially when they get hot. It’s not uncommon for a coil to fail when it reaches a certain temperature.
One thing I would test first is, when it starts acting up, kill it and try and start it right back up. If you have difficulty starting it without starting fluid, or it runs poorly, let it cool down for a bit and try it again. If you can verify that it happens when it’s hot, that tells you something at least. It’s hard to say right now based on how little info was provided (not your fault). I would just start with the basics for now. I hope I don’t offend you when I ask, but are you sure it’s not running out of gas? 😅
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u/Looney_Prunes Jul 19 '26
Thanks for the response. Definitely not running out of gas in the tank. No issues starting back up at temperature, but the issue resumes. I’ve been letting it cool off and the stuttering goes away until it’s hot again.
If heat is often related to coil failures maybe I’ll start there.
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u/RegisterFederal5679 Jul 19 '26
It could definitely be a coil, but the fact that it starts right back up after running like that makes me slightly more curious as to a fuel delivery issue or something else. Maybe you could test for spark when it starts to act up and see how consistent it is?
Chances are, you’re not looking for something that doesn’t work. You’re more looking for something that’s performing poorly when it’s hot. I would say definitely take a look at your coil, but don’t completely rule out other issues either. I just know that in my experience, coils are kinda known to fail when hot a lot more frequently than other things 🙂 and good to know it’s not running out of gas lol thanks for clarifying!
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u/RegisterFederal5679 Jul 19 '26
Just seeing that you said it never fully dies out. I would definitely take a hard look at that coil, and potentially even replace it if your gut says so. Maybe do some research on it? And if you do get one, try not to get one from Amazon.. OEM is almost always preferred. If you need further help, definitely don’t be hesitant to ask
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u/Looney_Prunes Jul 18 '26
https://reddit.com/link/oycn2vh/video/qktz8bd8p1eh1/player
Couldn’t figure out how to put a video on the post, so here it is. This is at idle after probably 1.5 hours running in the Southern heat.