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Buell Forum » Knowledge Vault (tech, parts, apparel, & accessories topics) » Troubleshooting (Poor Starting/Running/Handling/Ride Issues) » Would a voltage regulator cause rich condition « Previous Next »

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Shredder
Posted on Friday, April 17, 2020 - 08:26 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Hello!

Got a new to me 08 Uly XT with 6k on it. Been sitting a while; years.

Needed a new fuel pump. Replaced with full OEM and did the plugs as well.

Starts and runs good, take it out for 16 miles and I the bike started loosing it. Speedo cycled, lost my tach, bike started stumbling, then backfiring, then dead. Died as I was cruising at like 35mph. Couldn't start it, seemed battery was gone. Parked for a bit, jumped it, ran the rest of the 5 miles home.

Sounds like a bad voltage regulator based on what I've read. Ordered, not received or installed yet.

I started it up today to check the AFV in BuellTooth and read it was at a 77.2. And holy cow did it stink like gas (rich condition out of the exhaust, not like a leak). I rode it and let it idle. My clothes reak like gas!!!

Anyone think the voltage regulator could cause this issue or should I start trouble shooting the O2 sensor, idle speed controller, and/or fuel injectors?

Thanks!
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Shredder
Posted on Friday, April 17, 2020 - 08:29 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I should add that I don't believe it smelled like this when I rode it last time
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Tpehak
Posted on Friday, April 17, 2020 - 10:00 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I would check grounds, battery terminals and would test voltage regulator first prior ordering new unit. Do this now while you are waiting the new VR.

Weird things might happen when there is not enough voltage. You can not ride you motorcycle with bad VR anyway so once you will have troubleshooted the VR you have to set the AFV to 100 in the program you used to read AFV and start riding your motorcycle and see if the problem still exists.
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Shoggin
Posted on Friday, April 17, 2020 - 10:46 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Did you actually test for a bad VR, or just hoping?

That extremely low AFV is the ECM trying to remove as much fuel as possible. Since you say it still reeks like gas, it could be something like a stuck injector? All anyone can do is guess without further info.

You can take it to a V-twin shop, but since you already have a Buelltooth dongle and ECMDroid, you will be able to do a lot of testing, the service manual can help with the diagnostic path. Theres a free manual download at Buellmods.com or Buelltooth.com
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Tpehak
Posted on Friday, April 17, 2020 - 11:15 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

The problem with VR, with stator or with rectifier wiring can be intermittent and test might show good VR so install permanently voltage gauge on your motorcycle you can see during riding so you will exactly know if the rectifier has problem or not.



I am also not sure how you figured out you need to replace the fuel pump, but this mod will allow you constantly see the fuel pump condition and will save you a lot of time, money and frustration
https://www.buellxb.com/forum/showthread.php?55083-Buell-XB-fuel-pressure-gauge&p=608998&viewfull=1#post608998

(Message edited by TPEHAK on April 17, 2020)
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Akbuell
Posted on Saturday, April 18, 2020 - 12:09 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I would start with a systematic approach.

The instruments cycling indicates an electrical issue. First, confirm battery connections are clean and tight.

With a known good battery, start the engine, and with a multimeter attached, see if you get something in the 13.5-14.5 volts at 3k RPM. If so, the voltage regulator is most likely good. While holding the RPMs, see if voltage is constant, and wiggle the harness where it plugs into the ECU. You may have a seat rubbing the harness issue.

If no problems, try taking the air box cover and air filter out. Turn ignition and stop run witches on, but don't start the engine. Run the throttle from closed to open 4-5 times, holding one second at each stop. Turn switches off, then open the throttle and look inside the intake manifold with a strong light. If an injector is leaking, you will see raw fuel in there.

And check all grounds and connections to confirm good contact. Same with all the fuses and relays.

Hope this helps, Dave
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Shredder
Posted on Sunday, April 19, 2020 - 12:34 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Thank you all for the help and suggestions. Iíll start going over it today and report back.
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Tootal
Posted on Sunday, April 19, 2020 - 04:19 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

If your VR test bad be sure and test the stator. If the stator is bad it will fry a new VR. I think there are 3 test for the stator and it must pass all 3 or it's toast. Another quick test is to remove the primary cover with two screws. Give it a whiff. If the stator is toast it will smell nasty in there!!
It was mentioned to check your grounds. One bad spot is on the goose neck at the front of the bike. There are 3 wires that share a ground screw. Many times the wire breaks inside the insulation and it looks good but it's not.
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Gabby_duck
Posted on Tuesday, May 05, 2020 - 06:36 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Look at top of the ECM, known issue is seat pressure causing cracking along the seam line of the grey or black part of the ECM connector male side.(the upper side that contacts the seat. Take picture of the top of your ECM and post. Start bike and do wiggle test on the wiring harness near the ECM to try to recreate issue
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