Likely can't: boats don't have manuals like cars generally speaking. Probably get a shop manual for the outboard, and then ask questions on the forum for the rest of it.
Starcraft, Sylvan, Smokercraft family have changed hands several times in the past 40 years. Doubt you will find a manual.
And doubt it would contain anything useful if you did find one.
No wiring or plumbing diagrams.