Power Macintosh G3 systems running Mac OS 8.5.1 have Apple System Profiler version 2.1.2 installed. This version of Apple System Profiler does not list FireWire under Devices and Volumes. Versions 2.2 and higher of Apple System Profiler do list FireWire and its driver version number.
See the following Tech Info Library article for additional tips on troubleshooting FireWire devices:
Article 24831: "
FireWire: Testing Ports"