No real manual to speak of, there are engine manufacturer manuals out there though. Best bets are to drain the gas because it is most certainly bad. Check hoses for condition especially the fuel lines. New filters all around, new oil, new raw water pump impeller for sure even before you try and fire it up because that is shot I bet and will shed vanes to get lodged somewhere downstream and that will lead to an overheat situation. I am sure there are more but that should keep you busy for a day or so.
'86 Comp TS6M - Reborn 2016
Riding a HO Sports CX Ski