1992 Saturn SC "hard wired smoke detector going" Questions

...hard wired smoke alarm has had a new 9 volt battery installed and even a second new one installed and is still chirping 4 times every 30 seconds. I shut off the switch at the fuse box for the smoke ...

...hard row to hoe. for sure. compression at 150psi, or more on all cylinders.? at wide open throttle. ( a $20 tools, dirt cheap and 30min work) alldata.com has the full spec. on that . as does ...