New Thread- Funky Fuel Cap Fixed

[montmil]

At the end of this post are links to three different threads with a common thread... Some of the freakin' funky BMW fuel filler caps do not vent to atmosphere and, in short order, can cause the engine to stumble and die. Often, in the most inopportune location.

First off, here's a tip of the R65.Org hat to Bill, aka, R80Rider, out in San Diego. And a raccoon hat tip to Snowbum's site with his info on the notoriously flawed BMW fuel caps.

So, here's the real deal and how I finally fixed my cap venting problem. As always, YMMV.

Remove the fuel cap and place it in an inverted position on some toweling to keep it steady. Note the four holes in the bottom surface of the fuel cap. Hole is misleading as closer inspection reveals the four holes are sealed off by a black plastic interior component. They do look like holes but, in actuality, there are not four holes in the bottom surface of the cap.

Select a drill bit that closely matches the size of the existing non-holes. Equidistant between two of the non-holes and a similar distance from the perimeter of the cap, drill through the metal surface and continue through the black plastic interior. Expect to drill not much further than 1/8" to 3/16". With the drill bit still in the cap, blow away any drilling debris that might accidently fall into the fuel tank.

Replace the modified fuel filler cap. You have now created a functioning vented fuel filler cap.

I just returned from a lengthy test ride and had no, nada, zero venting issues. I kept an eye on my translucent in-line fuel filter -it has an i.d. of approx 1" x 1.25" long- and the fuel never wavered from its maximum capacity. Previously, my fuel filter would be all but empty when the stutter n' stop would occur.

Should you suspect a similar problem with your fuel filler cap, this is an easy experiment and/or fix. You can always solder the hole shut if you wish.


http://suraklyn.com/yabb/YaBB.pl?num=1214254109

http://suraklyn.com/yabb/YaBB.pl?num=1208621378

http://suraklyn.com/yabb/YaBB.pl?num=1215528453

[Yikes]

Like you Mont, I had a cap that had been filled with epoxy and was a solid plug.  Afrer removing a little plate that had been epoxied to the top to cover the hole where the lock hads been removed, I drilled the epoxy out of the center with a bit a little smaller than 1/2 in and then usd a 3/32 bit the drill out the upper holes in the cap.  Those upper holes had to be drilled in at an angle since the bit kept encountering the hardened steel pieces of whatever was left of the lock mechanism in there.  I then followed Snowbum's advice drilling up from the bottom of the cap, but contrary to his instructions, I drilled into the center to find the center hole I drilled.  I then re-glued the plate on and now have a vented cap.  No more stalling or riding with the fuel cap half unscrewed.  There is no lock on the cap, but that's OK if I can aviod buying a replacement.  There are more than plenty of other parts on my "need to buy" list.