Careful
 

Be careful when using Automotive starters and Generators. Marine versions are usually encapsulated in the brush/commutator so no spark is exposed. A little gas vapor one spark...BOOM!

Also many engine versions have a slave solenoid (not the main starter solenoid) which are common for going bad. Jump the slave solenoid (usually looks like the trim pump solenoids, but mounted on the engine). If she turns over replace the solenoid. If not best bet is the starter.