Joined: Jun 2007
Location: Killington, Vermont
Just trying to be helpful ...
Flys Lo et al, hi!
Your dilemma is exactly what mine was a two years or ago. My 1100GS would run fine until mile 122. Well it might have been a few miles either way, but that was the number that stuck in my mind. From a full tank to about that mileage the bike would run great. Then all of a sudden it would stutter, hiccup is more like it, just stop running for a few seconds. When rolling back on the throttle it would go again.
The first time it happened was on a three hour ride, a bit time critical to make it to an appointment. For the last 50 miles, it would hiccup every couple of minutes. After the appointment, the bike came apart, tank off, seat off, panniers off, just about everything, looking for wiring issues, and leaks. With all the parts and my gear strewn around the parking lot it looked like I was having a yard sale! After fiddling with everything, it all went back together, and I filled up with gas. On the ride home, at mile 122 it hiccuped! Filled the tank and all was good again.
At home everything came apart again. This time, the fuel filter was changed. The old one looked great, but a new one went on. Rode around, the bike ran fine ... until about 80 miles on a tank and going up the steep passes of the mountains here in Vermont, and it hiccuped again.
Oh, when the tank came off at home, many of the various things suggested above were done also, including putting compressed air in the vent line. There's a lesson to be learned from that. Inside the tank, near the filler is a container that one of the vent lines goes into. It's got a pin hole vent in it. At 160psi, that little 2 inch by 3 inch by 1 inch hollow unit make the loudest bang I'd heard all day, and split in half.
That came out of the tank by taking the filler off. When seeing it was split along the seam, longitudinally, my first thought was superglue or epoxy. Being in gasoline all the time, that probably wasn't a perfect idea. So in addition to epoxy, using a fingernail file, I put notches on the outside edges. Then from the days of rally cars, there was some fancy wire and spinning pliers around, that we used for wiring nuts and bolts. a wrap of that wire, tightened down with the spinney pliers, made that little hollow thing I'd blown in half, pretty secure.
Okay, back to climbing the mountain passes and the bike hiccuping. All the way up to the top, it would hic every couple of miles. On the downhill side it ran fine. After being fueled up, all was good.
Oh and trust me, I read every thread on ADV that had anything to do with fuel pumps and gas tanks. Finally, I ordered one of the Bosch 6222 pumps (off the top of my head, that might not be the correct number) that went in a 1992 Chevy Something or Other, for $50. When it arrived, carefully the soldering was done, and everything put back together.
That was two years ago, and something like 40,000 miles, not another hiccup since.
Here's what I think. One thing that I did was put a fuel pressure gauge inline. When the key came on, the fuel pressure would go up to 42pounds, maybe it was 43, but something like that. And a couple of moments later it would go back to zero. In my mind, it seemed to me that once the pressure was up, it should stay up, but it didn't. And honestly, I haven't been able to find anything that says it should stay up at 42. Shouldn't there be a check valve in the pump? Any thoughts from those in the know would be appreciated.
My belief is the pump was staying cool as long as it was in gas. When the tank got below the 122 mile level the pump was exposed to the air, and would overheat. My guess is the pump in the bike was the original one, with 80,000 something miles on it. So it served it's time.
My plan (which hasn't been done yet) was to dissect that pump to see if any brushes inside were worn way out, or there was something wrong with the windings, or a bearing was gone, or just see what was in there. Maybe it was something to do with the impeller slipping on the shaft, who knows. But from your description, it sounds just like what happened to me.
How's that for a rambling thread jacking (good story def?)? Am I making sense?