Re: 85 H.P. Johnson Starting Problems
it has to turn +-300 rpms to start, so it is possible. take starter to a starter/alternator shop, and have it tested.
90% of starter problems are bad connections. remove and clean both ends of the battery cables, so that they are shiney, also the cable from the solenoid to starter. check for nicks in the cables. and make sure the connectors are on the wire good. the cable tend to corrode from the inside out, if nicked, corroded wires, and connections, heat up and cause resistance to the follow of electricity, thus the starter doesn't get enough. you can also take jumper cable pos battery post to large post on starter. with a good connection, the engine should spin. then if the starter is good clean everything and retest. then trouble shoot solenoid. starters can be rebuit at a starter/alternator shop, much cheaper than a new one.
also have the battery load tested at the auto parts store, free, i've had new batteries go bad
here are 6 pages of test, find your motor
http://www.boatpartstore.com/page28.asp