2008 soft tail. Miss fires - no power - black smoke after fill up. Will clear up after holding throttle wide open for a while. Traveling with a group back to Milwaukee in the Nashville area now. Anyone seen this before? Looking for suggestions.

 

Are you over-filling? I've had that happen as well. It's almost like vapor-lock. Usually unscrewing the gas cap off and back on fixes the issue. That and ripping the throttle as you mentioned.

 

Happened right after fill-up...bad gas?

 

1st thing to check. I've been reading more and more problems with water in the gas.

 

Had the same thing last month in New Mexico on a Heritage. Right after fillup, would barely run, stalled on the on ramp for a momentary coughing, spitting, hiccup fit, then it ran fine. Seems like bad ga would have lasted longer. Would the ECM be making an adjustment to the altitude or octane level? This happened twice, both times in NM, both times at lower octane, both times at higher altitude. Both times were only for a minute or so, then fine.

 

It's not water in the gas if the problem goes away after blipping the throttle.

I've heard a number of people have this happen....it's usually the tank was overfilled.

 

Happens even if its not filled up all the way. Starting to think it might be sludge in the tank that gets sloshed to the pick up screen when fuel is added. Turn on the pump....and it gets sucked up???? A little vibration and some falls away???

 

Something that happened with my Ducati / Magneti Marelli FI system - It did something similar after I had richened up the idle CO. It had problems starting when it was already warm. I was told that the MM system went through a cold engine enrichment cycle whenever the bike was started whether it was cold or hot. When I upped the idle setting it made the bike super rich when it was warm and restarted. Not sure if Harleys with a MM system might do the same thing.

 

""""I've heard a number of people have this happen....it's usually the tank was overfilled.[/QUOTE]"""

How can you overfill a tank? I have spilled over several times(dumb)
Maybe the "vent in the cap gets stuck/debris in it. because of sloshing)
that would cause a vacuum, and it might stall when the air didn't get in the tank .
but it wouldn't be immediately after refill. ???

 

"""

How can you overfill a tank? I have spilled over several times(dumb)
Maybe the "vent in the cap gets stuck/debris in it. because of sloshing)
that would cause a vacuum, and it might stall when the air didn't get in the tank .
but it wouldn't be immediately after refill. ???[/quote]

From what I was told, you have the right idea with the vacuum description. I do know removing the cap and reinstalling the cap does clear the issue. I've had it happen a few times with my bike...and I know it's not bad gas/water etc.