In response to Delph Wilson’s comments in the June, 1977 issue concerning gasoline leakage from a BMW fuel filler, I too had a similar problem. The gas cap didn’t form a tight seal due to a 1/8 inch gap between it and the filler neck.

Fritz Peterson of BMWNA provided the following list of checks to be made to resolve this problem. These are:

BMW Fuel Filler Gas Leak Checklist

1. Assure that the gas cap has been sufficiently tightened. Turn cap until ratchet mechanism has clicked at least two times.
2. Check rubber seal on filler cup to insure its integrity.
3. Check filler neck to assure that no damage has been done by a gas filler nozzle. Damage to the neck will prevent a good seal.
4. Inspect cap for proper manufacture and replace if necessary.

In my case, the cap was defective and replacing it cured the problem. Incidentally, the gas cap is one of the items covered by the five-year/50,000 mile emissions control system warranty.

Author: Robert L. Kreger