Terry, I had a guy show up at the shop with a GS on a pickup truck.. it sat all winter, not properly prepped... said it wouldn't start. It had the adventure tank, which I'm sure you know is a big deal to the GS crowd... I pulled the tank.
In the past, I've revived a few fuel injected bikes that were stored improperly long term, and found a crystaline 'marble' or chunk in the pump, fuel line, or right at the injector. This is SUGAR, which grain alcohol contains in large quantities. (actually, i can't believe this discussion hasn't touched on that). Ironic that sugar in a gas tank was something people used to vindictively do as a prank, and now we put it in willingly. I am not 100% sure why that effects fuel injected bikes more, but I theorize that the uni-directional couplers prevent backflow, and the small section of fuel line that remains pressurized starts to separate out the sugar and deposit it at the injector. I've seen it a few times. The worst case was a Ducati SuperSport. It had a chunk right at the injector, in the fuel line. When I sliced the line open with a razor blade, I got what looked like a yellow advil liqui-gel.
Anyway, I expected to find exactly that in the fuel system of this GS. I pulled the pump/pickup/sender unit. The pump motor had indeed burned out. The armature was blackened, the bearings were seized hard and egged out. There was that yellow-y sugar crud all over the impeller, BUT a reddish-brown slop was all inside the tank. I could see that it had peeled off the innards.. so there was bare steel in places, and that goop in others. It was a goddamned greek tragedy inside that thing. I called the dealership, who confirmed that the tanks were indeed lined from the factory for awhile. I'm unsure if it was only the short-lived adventure tank or not, but since that thing was really hard to replace, I spent a couple days cleaning it out, using a few different methods.
I'll never do that again.. you just can't bill for all those hours, but I'm glad we saved the tank, and the paint job, and that he was on the road again.
Hope you never come across it.
