BMW Springs a Fuel Leak: It’s Always Something…

Gasoline WarningAbout two weeks ago I start to detect the smell of gasoline fumes in the garage.  It seemed to be coming from one of the three motorcycles, noting both of the Harley-Davidson’s intermittently vent off gasoline fumes for no apparent reason. Sometimes I’d notice it after shutting down following a long ride, other times it showed up after a short ride.  Weird, but… well, they’re Harley’s not Hondas.  However, in this instance it wasn’t just gasoline vapors coming out of a vent tube, it was much stronger… indicative of a liquid fuel leak of some type.

After looking around and not finding any visible signs of leakage I wrote it off as “just one of those things”. That was, until the next day when I clearly could smell gasoline fumes as I climbed on the BMW for the ride home after work.  Again, no clear sign of leakage so rather than trying to troubleshoot it in the parking lot, I took a risk and just rode it home.

Patient ReadyOnce I was at home and in the garage with the bike in the wheel chock a closer inspection revealed a small fuel leak at a quick-disconnect coupling.  A quick-disconnect coupling I didn’t even realize was installed on the fuel system until just then.  I’d heard about these things and knew the older plastic male ends were notorious for fatigue failure, but never thought to check and see if a pair of these had been installed on our R1100S.

Anyway, after finding the small leak I probed around a bit and next thing I know I’ve got fuel pouring out of what turned out to be a fractured male fuel connector buried under the bike’s bodywork!  What a mess that was, as it took me a few minutes to get a clamp on the fuel line above the broken quick disconnect to stem the flow of fuel: I’m guessing at least a quart of fuel ended up all over the engine and floor of the garage.

Cowls OffWith the root cause of the fuel leak diagnosed and the leak stopped, I pulled the cowls off so I could unbolt and raise the tank to get a full assessment of what I had to work with to fix the problem: was it a simple connector swap or did other issues need to be addressed?

Broken ConnectorWith the tank raised, I could clearly see that the male end of the connector was broken off in the female, quick-disconnect housing, hence the free flow of fuel vs. the quick-disconnect doing its job and shutting off the fuel flow.  I also discovered the plastic fuel rail connected to the fuel hose feed from the tank had been crimped at some point, which was clearly not a good thing.  The other interesting discovery was the lack of a second quick-disconnect on the fuel return line, which was really weird: these are only really useful when they’re installed in pairs.  I’m thinking there was a relationship between the kinked fuel rail and the quick disconnect that had to date back to the original owner back in 2003-2008 when only 4k miles were put on the ODO.

Tank OffWith that quick assessment complete, I disconnected the return fuel line and pulled the tank off the bike so I could get a better look at the fuel lines and the damaged fuel rail.  It was clear that at 10-years old, the fuel lines needed to be replaced, as did the broken male quick-disconnect.  I’d also need a second quick disconnect for the return fuel line and would need to either replace the fuel distribution assembly or reinforce the kinked fuel rail; I opted for the latter and reinforced it with some clear tubing.

With my shopping list in hand, I visited my local BMW dealer – BMW Ducati Husqvarna Motorcycles of Atlanta – and had my friend in parts, Joey, order the bits and pieces I’d need to make the repair.  They had a few common parts on hand, but the repair would have to wait until I could pick up the countoured fuel lines when they re-opened on Tuesday, October 8th.

With all of the parts needed in hand, this past Tuesday night I went ahead and pulled off the air cleaner and serviced the K&N filter while the bike was apart and set about to replace the fuel feed and return lines with the new quick disconnects as the filter dried.  While the quick disconnects work well, they’re a PIA to fit in and under the tank, never mind to reach.  But, it’s still a heck of a lot easier than trying to pull the fuel lines off the fuel rails when the tank needs to be removed.  Speaking of PIA parts, as much as I like the compact design of the standard BMW fuel line crimp-clamps, they’re not exactly re-useable so I opted to go with traditional clamps. They look awful and create some potential chaffing issues with nearby wires and lines, but they’re a lot easier to remove and re-install than the one-time use crimp-clamp.

Female shut-off values Male connectors

About the only thing I should have done but didn’t was to replace the fuel filter while I had the tank off.  Oh well, I also didn’t get around to cleaning the motor while I was in there. So, I’ll probably order a filter and a new alternator belt and replace both of those in the next month or so, if only so I have a chance to use my freshly re-installed quick disconnects!

BTW, if you think your battery is hard to access, you should see where it’s installed on a BMW R-series bike and, the R1100S in particular:  talk about being buried!  You either have remote jumper leads or you take the bike apart to get a jump if the battery dies…

Battery 1 Battery 2
Anyway, the bike fired right up.  After a quick throttle sync and putting the bodywork back on, it was back in service pulling daily commute duty.  It’s a sad existence for a bike that should be tearing up the twisties in the mountains instead of making mudane trips through the Kennesaw National Battlefield Park twice a day.

Ready to go again...

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About TG

I've been around a bit and done a few things, have a couple kids and a few grandkids. I tend to be curmudgeonly, matter-of-fact and not predisposed to self-serving chit-chat. Thankfully, my wife's as nice as can be otherwise we'd have no friends. My interests are somewhat eclectic, but whose aren't?
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