Thanks big time for the help guys.

I'm pretty sure that both car's systems are fine.

I haven't filled the 89's system in the over 9 years that I've owned it. It's just simply time.

The 92 has apparently also been unused for some time as well. I just found out that the "brand new" looking tires on this car are actually 14 years old!

Despite all this, both systems still have a little pressure left in them!

Do you guys agree that I have found the low pressure port?

__________________
89 300E "Benzer1" 15.924 Uncorrected
93 400E "Benzer3" 14.200 U.C.
95 E420 "Benzer4"
92 300E "Benzer5" 16.299 U.C. Future turbo CNG
87 300D "Benzer7"
87 300D "Benzer8"
87 300D "Benzer9"
87 300D/70 AMC Javelin "Sidewinder-Benzer"
87 300TD "Benzer11"
06 E320 CDI "Benzer12"
05 E320 CDI "Benzer12A"
71 AMC Javelin AMX 401 "Sidewinder"
74 AMC Hornet 401 "C.K.10" 13.63 U.C.
74 Bricklin SV1 "Presto" AMC 360 pwrd.