These were posted on another site but they're a great resource. Mostly Indmar and PCM but just tons and tons of good info here from basic owners manuals to advanced diagnostics and exploded parts diagrams for most common ski boat engines.
Start here if you're looking for manuals/diagrams.https://www.m2omarine.com/know-more-about--resource-downloads
If you can't find your motor there, check this site for more current models like the PCM GDI 5.3 and 6.2Lhttp://www.nautiquespain.es/shop/content/7-servicio-tecnico-manuales
I recommend downloading anything you find interesting from these sites. Who knows how long they'll be around. Wealth of info here though.