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Ju_le_new
Posted on Sunday, June 18, 2017 - 06:41 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Hi everybody, I have been a long time reader but this is the first time posting here. I have a problem with my buell and would love some input.

2005 xb12scg
Hawk exhaust, K&N, back to stock tuning (to see if my tuning was the problem).

A few weeks ago, I went on a ride and the bike started stuttering if I gave too much gas, to the point that I had a hard time accelerating. I suspected that my plugs were done.

I put some new HD plugs in there and then the bike would idle well but stutter and almost die as soon as I take off in first gear. Did some more investigating and at this point the bike won't even hold idle for longer than 10 seconds. I can rev it up, but it will eventually miss, stutter, backfire and die. It also smells gas.

I can keep the bike at 2,000 rpm for about 5 seconds and then it feels like it misses gas and just shuts off almost instantly. I can hear the sparks trying to ignite but it dies.

What I have tested so far :

- Repulled plug and verified gap
- Tested resistance in plug wires and installed securely with dieletic grease
- Tested coil resistance : everything ok
- Searched for any bad ground or short : everything ok
- Tested battery voltage with bike off, at idle and at 3k rpm. It goes from about 12.5v when off to 13.5 when on to about 14 - 14.5 at 3k rpm : looks good to me
- 77 connector is in good condition
- Stator testing (resistance and DC output) is ok
- Battery was tested and is 100%
- Tried another VR on the bike - nothing changed
- Shot WD-40 on the intake seals to see any change in the RPM : no change at all
- No code in the ECM
- Did multiple TPS resets

So after all of this, I suspect that either (1) my intake seals are bad but it did not trigger with the WD-40 test, or (2) Fuel pump is not holding pressure and the bike is missing gas. The fuel pump primes and sounds good to me though.

Here are my questions for you guys :
- Do you have any other idea of the source of the problem
- Any way to test if the problem if the fuel pump?

Any input is greatly appreciated!
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Teeps
Posted on Monday, June 19, 2017 - 10:53 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Check the cam position sensor under the round inspection cover. (my ulysses parts cat calls it a sensor assembly)

Is it melted?
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1_mike
Posted on Monday, June 19, 2017 - 11:02 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Sounds like mine (05, 12XB) did when the "Throttle Position Sensor" went out.

A simple swap, all was/is well.

Mike
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Ducbsa
Posted on Tuesday, June 20, 2017 - 05:30 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I had to replace my TPS a few years ago. Mine had the cable anchor as part of the plastic housing, but the used one I found to purchase didn't have that. I bent up an aluminum strip I had to make it work, so if you need a replacement, keep this mod in mind.


TPS a
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Ducbsa
Posted on Tuesday, June 20, 2017 - 05:34 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Here is the finished product:


TPS b
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Greg_e
Posted on Tuesday, June 20, 2017 - 02:05 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

That's a TPS? Mine is bolted to the side of the throttle body (03 9R and something newer 12). Isn't what you are showing the exhaust valve actuator?
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Ducbsa
Posted on Tuesday, June 20, 2017 - 02:22 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Jeez, sorry, that's the damn muffler valve actuator! Sorry for the confusion!


Edit: I had to replace the real TPS at the same time and they melted together in my so-called memory.

(Message edited by ducbsa on June 20, 2017)
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Audiowize
Posted on Wednesday, June 21, 2017 - 11:22 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Fire up your bike and let it stutter. Do both pipes get hot? When I had similar problems with my XB9 I noted that one pipe wasn't warming up and I had to track down some chafed wires to get it to fire.

I still had stumbling problems and had to replace my TPS. When you do the reset, carefully and slowly move the throttle and ensure that you get consistent voltage readings as you move the throttle. If it blips up or down (suddenly to 5V or close to 0V) during part of the rotation, toss that TPS and put a new one in.

The recommendation to inspect the timing sensor is a good one. I also found some chaffing on my timing sensor wiring under the front pulley cover that was giving me problems.

The fuel pump is also certainly an issue. Does it prime properly? Does your low fuel light work as expected? Any blowing fuses?

The fact that you can rev the bike up and make it happier suggests ignition or electrical.
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