2008 XB12SCG heat soak issue

[paulie wally]

Hi, first post. I am new to Buells. I have a 2008 XB12SCG with 24,000 miles. I've had it about a week and ridden it a couple hundred miles or so.

I love it and it runs good. I think I have an issue with heat soak, though. If I get it up to temp. and stop for a few minutes, it runs poorly when I start it up again. It runs rough and has trouble idling. It will also pop or backfire lightly, and power is down, but still rideable. One time, the check engine light even came on. If I wait an hour or two, letting it fully cool off, it's like nothing happened. It runs great again until I let it heat soak again. Only once have I had it start acting like this when I was still riding it. Otherwise, it only happens after I shut it off and restart it shortly afterwards. I filled it up with gas yesterday and it was fine, but that's only a couple of minutes. Anything longer and it has the issue. The fan does come on when I shut it down. It's been in the 70-85 degree range here so nothing extreme as far as outside temp.

The bike is completely stock as far as I can tell other than a K&N air filter. I haven't done much yet as I'm not sure where to start. I cleaned the IAT sensor with no effect.

I did download the Buell User Manual and the Electrical trouble shooting manual. I have started looking at them.

Any idea what direction I should go?

Thanks for any help,

Paulie

 

[Cooter]

Hello Paulie and welcome to the forum! Even without the CEL on, you can check historical and current codes without a computer (procedure in the manual), but i'm not sure it will tell you much.
You can also order a Bluetooth module (I like the one I got from Rev-Mo) that works with the program ECMDroid (free from Google Play) that will help considerably with diagnosis. This advise comes with the STRONG advise to NOT change or replace the tune. It isn't bad.

For now, how about the basics... Are the plugs clean? If it had sat for awhile, it is more than likely that repeated start attempts or a weak battery have fouled the plugs. They will act exactly like that in a semi-fouled state and it doesn't take much on a Buell. Iridium plugs work very well.

 

[paulie wally]

Thanks, Cooter! Are there any specific iridium plugs you like?

 

[Barrett]

NGK DCPR9EIX correct for all XB models. A tiny dollop of anti-seize on plug threads recommended.

If your engine has compression-fuel-spark-timing....it has no choice but to run. You are missing either fuel or spark or both.

The CEL in conjunction with engine shutting down AND back-firing/popping up thru the throttle body are your clues.
The ECM is seeing one or more of the following conditions that is activating the CEL:
1-Fuel pump loss of ground---Fuel pump resistance values outside normal parameters
2-Internal problem with ECM itself
3-Interrupted current flow or very low voltage signals from battery to electrical system
4-Back-firing up thru the TB is always fuel pump/lean condition indication

Recommendations:
Access your ECM then search active/historical fault codes. You will likely see NUMBERS 16-33-52-53-54-55

Replace IGNITION RELAY

Thoroughly clean and then tighten all 4 ends of your battery cables and check cable conditions closely

Unplug and remove ECM and check very closely for any signs of cracks and blistering/bubbling on the back-side of same

Remove OEM left-side air scoop...unplug and inspect and clean both VOLTAGE REGULATOR HARNESS PLUGS

Familiarize yourself with simple process of removing air-box cover and inner air-box lid. Then procure a small container of sorts that will hold 2 ounces or so of fuel. Carry it with you....go for ride until shut-down occurs...then quickly remove cover and lid and dribble small amount of fuel down into TB and attempt to immediately start with 1/3rd throttle. Engine starts???
Faulty fuel pump. Engine won't start??? Faulty ignition circuitry.

All your symptoms and clues point towards a failing fuel pump assembly.

 

[paulie wally]

Thanks, Barret!
That gives me some things to work on. It may take me a little while, but I will post back with what I find out.