2018 FLHX buzzing noise
Thread Starter
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4th Gear
Joined: Jun 2017
Posts: 8
Likes: 3
From: Dekalb, IL
2018 FLHX buzzing noise
Hey all,
Im seeing if this is an easy DIY instead of a pricy dealer fix. I have a 2018 street glide with 24k on it and theres an intermittent buzzing coming from under the gas tank (see video), sounds like it happens on some of the cylinder firings. I think Ive narrowed the sound to the harness group inbetween the cylinders/behind air intake. Just started doing it and noticed when at a stop, with the clutch in (once this starts) it idles at 2k then acts like its misfiring. No power loss or strange acceleration when riding though but it can be doing while cruising.
Any advice? Ive searched both ends of the internet and cant seem to find this same issue.
Im seeing if this is an easy DIY instead of a pricy dealer fix. I have a 2018 street glide with 24k on it and theres an intermittent buzzing coming from under the gas tank (see video), sounds like it happens on some of the cylinder firings. I think Ive narrowed the sound to the harness group inbetween the cylinders/behind air intake. Just started doing it and noticed when at a stop, with the clutch in (once this starts) it idles at 2k then acts like its misfiring. No power loss or strange acceleration when riding though but it can be doing while cruising.
Any advice? Ive searched both ends of the internet and cant seem to find this same issue.
Last edited by Shumthang; Aug 17, 2025 at 08:25 PM.
Tourer
Joined: Apr 2011
Posts: 447
Likes: 82
From: Paris ky
i would suggest getting you a stethescope and while making the noise listen to the fuel injectors and the fuel rail y-assembly.you can use a long screwdriver or extension alsomstick one end to your ear and the other to each component.should be able to pinpoint from there.
Thread Starter
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4th Gear
Joined: Jun 2017
Posts: 8
Likes: 3
From: Dekalb, IL
i would suggest getting you a stethescope and while making the noise listen to the fuel injectors and the fuel rail y-assembly.you can use a long screwdriver or extension alsomstick one end to your ear and the other to each component.should be able to pinpoint from there.
Seasoned HDF Member
Joined: Oct 2012
Posts: 11,226
Likes: 3,049
From: St.Louis Mo.
I would look at the front plug wire where it goes underneath the tank.. They rub though on the tank and will cause a misfire. Up underneath the tank.
Just a guess, but don't cost anything to look.
At least on the Twin cams it was a real problem.
Just a guess, but don't cost anything to look.
At least on the Twin cams it was a real problem.
Last edited by hardheaded; Aug 19, 2025 at 12:06 PM.
Thread Starter
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4th Gear
Joined: Jun 2017
Posts: 8
Likes: 3
From: Dekalb, IL
My other idea was maybe something intake wise, like a leak? Maybe a gasket buzzing havent had a chance yet to test that yet.
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Seasoned HDF Member
Joined: Mar 2010
Posts: 38,623
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From: Honah Lee
Not a clue but that's the strangest noise I ever heard on a Harley.
If you have a external vent. Make sure all you hoses are attached.
Make sure the purge cap is on the top of the throttle body. I assume you don't have a California purge canister.
You should be able to isolate that with a probe on a two ear mechanics stethoscope.
Do you have a code for a misfire.
May just be something loose or rubbing but that surge is more than that.
Something is giving it air probably and maybe with out fuel at that idle surge and if so, it's so lean, it's causing a miss.
That modern ECM is said to be OB2 with the adapter. It should throw some kind of error one would think.
Is your EITMS on causing the idle surge?
If you have a external vent. Make sure all you hoses are attached.
Make sure the purge cap is on the top of the throttle body. I assume you don't have a California purge canister.
You should be able to isolate that with a probe on a two ear mechanics stethoscope.
Do you have a code for a misfire.
May just be something loose or rubbing but that surge is more than that.
Something is giving it air probably and maybe with out fuel at that idle surge and if so, it's so lean, it's causing a miss.
That modern ECM is said to be OB2 with the adapter. It should throw some kind of error one would think.
Is your EITMS on causing the idle surge?
Last edited by Jackie Paper; Aug 19, 2025 at 03:06 PM.
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Thread Starter
|
4th Gear
Joined: Jun 2017
Posts: 8
Likes: 3
From: Dekalb, IL
Not a clue but that's the strangest noise I ever heard on a Harley.
If you have a external vent. Make sure all you hoses are attached.
Make sure the purge cap is on the top of the throttle body. I assume you don't have a California purge canister.
You should be able to isolate that with a probe on a two ear mechanics stethoscope.
Do you have a code for a misfire.
May just be something loose or rubbing but that surge is more than that.
Something is giving it air probably and maybe with out fuel at that idle surge and if so, it's so lean, it's causing a miss.
That modern ECM is said to be OB2 with the adapter. It should throw some kind of error one would think.
If you have a external vent. Make sure all you hoses are attached.
Make sure the purge cap is on the top of the throttle body. I assume you don't have a California purge canister.
You should be able to isolate that with a probe on a two ear mechanics stethoscope.
Do you have a code for a misfire.
May just be something loose or rubbing but that surge is more than that.
Something is giving it air probably and maybe with out fuel at that idle surge and if so, it's so lean, it's causing a miss.
That modern ECM is said to be OB2 with the adapter. It should throw some kind of error one would think.
No purge canister on the bike (IL resident here) but Ill check the throttle body. That was my next step to take the intake off and check seals since while this happens, it can idle at 2k coming to a stop. If I release and pull the clutch again it figures out the proper idle then.
Ive read if I get that far might as well replace with S&S and get rid of the stock plastic one.
No codes that I saw, went through all of that after I took the video.
Seasoned HDF Member
Joined: Sep 2008
Posts: 14,165
Likes: 11,255
From: San Diego, CA
Ditto: That is the strangest noise I've ever heard on a Harley...
If unable to locate it with just your ears, or maybe your ears and a length of hose, I'd invest in a good mechanics stethoscope for that one...
I missed it if you checked and found any codes?
Keep us posted, I'm dying to find out the resolution on this one...
