I dunno about this.
First question I have, is do you have film in the camera and is the ISO/ASA set to the right speed?
I have a roll of T-Max 100 in mine right now and tried your test with my 35-70 zoom stopped down to 22 and in Auto mode. I got an immediate firing - as you would expect when "wasting" the first two shots after loading the camera with film.
My batteries are fresh and I then checked with the cap off to ensure that I was getting speed fluctuation based on pointing at a light bulb or not.
Note: with the cap on I get a speed reading of "80" which is is not 8 seconds but 1/80.
I'll follow this thread and see what turns out.
Note: This F3 I'm using is one of three I have and was recently purchased so I'd have to check the other 2 to be sure. But they are about 2000 miles from where I am now!