R1250GSA post gas fill-up issue

[Lone_RT_rider]

After I fill up the GSA in the morning. I ride to work and park the bike in the lot outside with temps in the 80's and 90's and mostly sunny days.  I come back out after work and there's a small puddle of gas that has come out the overflow tube.  I have to imagine some valve in the evap system isn't working properly or something.  It continues to do this until I get a couple of miles and the tank drains down enough to have some expansion area in the tank.  

 

Does anyone have any thoughts on where in the fuel system to check or replace something that might not be allowing pressure to go where it needs to?

 

Shawn

[TSConver]

Are you just filling it until the pump clicks off or are you topping it off?  It is likely the actual liquid expanding and as a result it is running out.

[Lone_RT_rider]

3 minutes ago, TSConver said:

Are you just filling it until the pump clicks off or are you topping it off?  It is likely the actual liquid expanding and as a result it is running out.

 

I'm filling it up within a half inch of the top of the tank.  I do this with every bike I own (also R1250RT and R1100RT) and never have this issue.  This is not coming out of the tank to the overflow area and heading to the ground through the overflow tube.  It's coming out of one of the other tubes in that area.  

[Lone_RT_rider]

I'm wondering if the something in this system has gone bad.  

[lkraus]

You need to RTFM.

 

 

Fuel coming from an underground tank is cool.  It expands in your fuel tank and is being forced out through the charcoal canister, which is now full of gas and can no longer absorb vapors as intended.

 

Stop filling above the bottom of the filler tube and the "leak" will stop.  Only fill past the bottom of the filler tube if you will be riding far enough to lower the fuel to a normal level before parking the bike.

[Lone_RT_rider]

Thanks Larry, the graphic that shows the max level has clued me in to what might be going on.  I noticed a small hole near the top of the fill neck that I don't have on my other bikes. I did drill one in the neck of the R1200RT I used to have, but I don't remember having this issue.  If that hole is doing what I think it's doing, it's allowing the tank to completely fill around the neck and therefore removing most of the air/expansion area that helps to keep the fuel out of the canister. My other two bikes don't have this, and even when you fill them to the top of the neck, most of the expansion area in the tank still exists. Whereas there is little if any left in my GSA.  If I only fill it on the side-stand and let the pump click off and don't put anymore gas in, it should help alleviate the issue. 

 

[dirtrider]

Afternoon  Lone_RT_rider

 

Heed the above advise, if you overfill it like that then park the motorcycle you will soon find your emission evap canister totally plugged with goo & the fuel tank sides sucking in when you ride it for while. 

 

Not a problem over-filling it (a large number of us BMW riders do) just DON'T over-fill then park it. If you over-fill then ride it (right then) far enough to use up 1/2 - 3/4 gallons of fuel before you park it & let it sit. 

 

There is no valving that closes off after engine shutdown, just the opposite, everything opens to vent the fuel tank to atmosphere through the evap canister then out through the vent hose. 

[Lone_RT_rider]

Yep DR, that's the plan.  Unless I'm traveling tank to tank and getting right back on the road I'll be filling it on the side-stand and only to the bottom (not the top) of the neck for now on.  Both times that it happened were a fill and sit situation.  Ride almost all the way to work, get gas and park it at work in the hot sun.  It's happened only twice to me, so the canister should be ok for now, but I won't be doing it again. 

 

Besides, it's a GSA.... at 7.9 gallon capacity (presumably to the bottom of the fill neck) it's already the exxon valdese of BMW's. 

 

Oh, and good afternoon to you as well sir. :)