[saughblade]

For what it's worth, I've run about 40 tanks of gas (7,000 miles) through my '06 GS since picking it up last fall. Low tank, on a cold (sub-freezing), very windy day was 39mpg. High tank, riding the NC mountains around 40-60mph in mid-June, a hair over 50mpg. Most tanks between 44-48mpg. Cold weather and strong winds (regardless of direction) tend to drop the mpg a bit. Stop-and-go is hard on gas as well--on my summer vacation to NC, one tank included a half-hour moving at a walking pace through Pigeon Droppings--I mean, Pigeon Forge--TN. 42mpg. Tanks immediately before and after that one were 47-point-something.

There is also some good info on real-world GS gas mileage at fuelly.com

 

[saughblade]

Your fuel gage should be accurate once you understand how it works.

The problem is not what the gauge does, but what you expect it to do. Report for re-education at once! Achtung! :wink2:

The float is in the left lobe of your tank. The fuel return from the pressure regulator goes to the right lobe of your tank. It drives a siphon (called the sucking jet pump, I believe) whose job is to constantly move fuel from the right lobe to the left lobe. This negates the need from a crossover line at the bottom of the tank.

A $108.28 (US price) "sucking jet pump" (and yes, that is what it's officially called) in place of a dollar's worth of rubber hose... if you ever wondered how Germans differ from pretty much everybody else, this defines it!

(I suppose I should add here that I'm about half German, so this makes perfect sense to me...)

 

[saughblade]

Two Other Possibilities (one fairly dumb)

BTW, this is after a new fuel pump sending unit recall fix.

Just a dumb question... is there any chance the trip meters got reset by the fuel pump fix? I know from experience with my '06 that if the battery gets disconnected everything in the display (trip meters, clock) will be reset. This could explain that 35mpg... especially if it returned to something more "normal" (42-50) afterward.

Another interesting possibility is found on the MOA board (scroll to post #13):

My mlileage is right in line here with all the others. But, the low 30s happened to me too(once) the first year I had the bike and confused me. My only variable was a new battery change from BMW(just before) and that apparently effected the throttle memory, which they all have now(throttle memories)! To correct it, disconnect the battery and leave it for 10 minutes or longer, reconnect it and turn the key ON, motor off(not running) and twist the throttle "three times" to FULL open and let go each twist of the throttle. This is right out of the BMW shop manuals how to reset the TB settings to the throttle. Mine got better afterwards and the mileage improved within one tank of gas.

Again, if the battery was disconnected as part of the fuel pump recall. I have seen other references to the "twist it three times" ritual, though I have no idea if it's a real thing. Nor do I know if the "throttle memory" thing goes all the way back to the '05s; the MOA post concerned an '08. Still, if you're continuing to get crappy mileage you might want to give it a try... and if you do, by all means let us know if it worked!