Original owner finds a *sputter*

[Bbennett]

Took V11 sport out for a long drive yesterday (this bike is single owner and is used alot and runs quite well in the mountains) and the bike began to have particularly bad flat spot around 2800rpm which I attributed to the warm temps and city driving as I re-entered town.  Then it got really bad ......lots of coughing.  Fuel light flickered.  Backfire.  Time for a fill-up.  With new gas she was happy. 

So let me think about this.  The tank was not empty by a long shot and now I have a new theory that I have some very nasty old gas and crud in the bottom of each fuel tank "lobe."

[docc]

How many US gallons was the fill-up?

[footgoose]

6 hours ago, Bbennett said:

  The tank was not empty by a long shot and now I have a new theory that I have some very nasty old gas and crud in the bottom of each fuel tank "lobe."

agreed... first place to start.

[Scud]

I wonder if it could be caused by water in the gas tank. If you can get a small hose into each "lobe" you can siphon a bit out of each side. Then run the bike towards empty closer to home to see if the problem repeats.

[docc]

5 minutes ago, Scud said:

I wonder if it could be caused by water in the gas tank. If you can get a small hose into each "lobe" you can siphon a bit out of each side. Then run the bike towards empty closer to home to see if the problem repeats.

No way! How could that happen?

[docc]

@Bbennett deserves his own topic, IMO.

I hope you're cool with this, Bb! We all want to pile on and fix your Sport from the comfort of our comfy seats and glowing monitors.

And, as much, not let our V11 fall prey to "What-ever-it-was" . . .  

[po18guy]

1 hour ago, docc said:

No way! How could that happen?

Oh, B.C.'s weather is not that nice...

Wait! I thought Bbennett was in Vancouver...???

[MartyNZ]

Fuel pumped past the injectors returns to the tank through the pressure regulator. You can drain any water/old gas at the bottom of the tank by disconnecting the hose at the regulator, and collecting the fuel as you turn on and off the ign switch. About half a cup will come out each prime cycle. 

[Bbennett]

7 hours ago, docc said:

How many US gallons was the fill-up?

I believe I added about 4.1 US gallons

[Bbennett]

1 hour ago, po18guy said:

Oh, B.C.'s weather is not that nice...

Wait! I thought Bbennett was in Vancouver...???

Nah, I live right here in the Seattle neighborhood of Ballard.  I WISH I could ride to Vancouver (BC) right now though (border closed).

[po18guy]

3 minutes ago, Bbennett said:

Nah, I live right here in the Seattle neighborhood of Ballard.  I WISH I could ride to Vancouver (BC) right now though (border closed).

Well that makes two Ballabios in King County and another in Vancouver. Got confused as Phillarsen has a Ballabio up in B.C.

[Bbennett]

33 minutes ago, MartyNZ said:

Fuel pumped past the injectors returns to the tank through the pressure regulator. You can drain any water/old gas at the bottom of the tank by disconnecting the hose at the regulator, and collecting the fuel as you turn on and off the ign switch. About half a cup will come out each prime cycle. 

Like milking a cow! 

[docc]

1 hour ago, Bbennett said:

I believe I added about 4.1 US gallons

Yep, that is low fuel on an early Sport (chin-pad, external pump/filter) tank.  The right "lobe" holds up to 0.8 US gallons of "fuel." Or is it half (or more) of accumulated detritus, water, and "binary azeotropes?"

Draining the fuel from the regulator return hose will only drain the left side "lobe."  The right side lobe will have to be siphoned from the filler at the top, or the regulator removed, or the tank removed and turned on its head.

Fully draining your tank should be properly shielded from the public eye . . .

@czakky knows how I wait for these moments . . .

[Cabernet]

What year is the V11? I understand the last ones had tanks with integral pumps. I had similar symptoms with my Nevada ie. Was a split hose causing reduced pressure to the injectors. The escaping fuel leaking back into the tank. The fill up increased the pressure just enough to hide the symptoms for a while, but ran pretty lean bluing  the can and eventually failed completely.

[Cabernet]

Another theory. On an external pump tank. Does the regulator valve not have an exposed spring that corrodes? Would a failing spring not cause reduced pressure and would the head of fuel from a fill up not increase the pressure slightly masking the issue.