My 90 Synco Westy passed the hard parts of Atlanta Metro emissions
testing this weekend, but failed the open book portion -  pressure
testing of the 2 year old OEM locking gas cap.

The same thing has happened each of the past 3 years, but previously
the testing wonks had been cooperative in fiddling with with adapter
to get a pass or waive the cap test. Not so much this weekend.

I found a suitable replacement cap that was visually and pneumatically
acceptable for the test adapter.

The new cap passed the test without much problem.

I did have to bend the ears on it slightly to get a tighter seal on
the filler neck.

The Stant cap shall now hold a place of honor in my glovebox until my
test next year - the OEM locking cap is back in place.

The details -- Stant  #10843 - some 90's era BMW gas cap. Cost me $15
at Pep-Boys.

The general consensus seems to be that the Syncro gas cap is just a
bit too tall to allow a good seal with the designated (red) testing
adapter.

Hope this helps somebody else. YMMV.

Later,
Jon
90 Syncro Westy -- Milton
Alpharetta, GA