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Buell Forum » Knowledge Vault (tech, parts, apparel, & accessories topics) » Troubleshooting (Poor Starting/Running/Handling/Ride Issues) » Buell s3 fueling issue « Previous Next »

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Rastapopoulos
Posted on Wednesday, May 29, 2019 - 08:21 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Hey yíall Iím the proud new owner of a 1997 buell s3, itís got a ham-can air cleaner and a supertrapp muffler, otherwise stock (to my knowledge), ~33k miles on it. I have an intermittent issue where the bike will pop and spit, typically out of the carb. Normally I would think lean conditions, but itís only happening at fairly specific times, typically when Iíve been running over 4K rpm, then slow down to idle (say, at a stop sign), and blip the throttle or roll on. Furthermore, I need to switch to the reserve tank at about half empty (over 2 gallons left), is that normal? Lastly, one time, after riding all day at highway speeds, it starved out at 70mph. Scary, but so far itís only happened once in about 800 miles Iíve ridden it. Iím suspecting either a clogged petcock or a faulty tank vent, is this a pretty reasonable suspicion? Or possibly a sticking float needle? Iím coming from the SOHC Honda world, and Iíve dealt with all these things on my 750, but Iím hoping to get a second opinion before tearing apart the fueling system on an otherwise excellently running bike. Iím really enjoying this bike other than this minor issue. Glad I got it over sportster I was planning on.
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Dave
Posted on Thursday, May 30, 2019 - 06:58 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Sounds like carb rebuild kit time to me. Especially at 33K. I have a love/ hate relationship with carb rebuilds. I always find plenty of "ethanol goo" & grit.

Similarly, intake seals can cause some similar symptoms. I can't think of a reason for the 2 gallon (80 mile?) reserve unless the petcock was replaced at one time.

DAve

(Message edited by DAve on May 30, 2019)
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Cdnrider
Posted on Thursday, May 30, 2019 - 02:40 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I agree that it could be gummed up Jets, but I am having continual issues with my Blast and it turns out that bypassing and removing the charcoal filter and running the vent hose directly from tank to carb creates a vacuum for some reason. I diagnosed by pulling the vent hose from the tank cap when the starve situation arises. My current fix was inserting a t-intersection and a section of hose feeding into an inline fuel filter to allow the carb/tank to breathe without sucking in debris.
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Rastapopoulos
Posted on Thursday, May 30, 2019 - 03:20 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

DAve,
Yeah thatís the next step if I canít figure it out easily. I just donít want to stop riding it for a whole weekend to rebuild!
Cdn,
On close inspection, the PO had the tank cap vent line venting just into the atmosphere. Same with the head breathers. Could this be the cause of my issue? Is it supposed to connect to the carb to create vacuum? Apologies if thatís a daft question, like I said I only know SOHCS, and so far I havenít found buells diagrams particularly helpful.
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Rastapopoulos
Posted on Thursday, May 30, 2019 - 04:05 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

After browsing some forums I think I found the issue. The tank cap vent ďrollover valveĒ appears to be stuck, as I canít blow air through it. Also, this particular part was recalled for the model year so it follows that it might be faulty. Iíll order a new one and report back. Also, I contacted the mechanic that the PO took the bike to and he told me the carb was rebuilt last year.
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Dave
Posted on Thursday, May 30, 2019 - 06:50 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Interesting
I hoped it's as easy as the vent.
DAve
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Ocbueller
Posted on Thursday, May 30, 2019 - 07:20 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Shortening the petcock tube for the primary fuel line may cure your early reserve problem.
SteveH
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Daddio
Posted on Saturday, June 01, 2019 - 10:19 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Another thing for you to consider is, if it is a vacuum-operated petcock, the diaphragm may be on its way out, which causes intermittent fuel-starvation issues.
The petcocks USED to be rebuildable, but I found with my last carburetted Harley, the service parts are obsolete.
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Cdnrider
Posted on Sunday, June 02, 2019 - 12:10 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I had vacuum issues and creating a t-intersection with a vent to atmosphere with an in-line filter actually cured my use. The direct line from carb to tank was causing my issues. If itís a vent valve issue then popping your cap when choking arises would cure the problem.
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Cdnrider
Posted on Wednesday, June 05, 2019 - 01:58 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Correction - my vacuum issue is better but not solved. I still need to remove the overflow vent line from time to time. Any input would be appreciated to alleviate this issue!
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