Re: Sport Jet 120 Starter Motor
Agreed, most often corroded connections are the main issue. Some additional testing:
Make sure that the battery is fully charged. Get a voltmeter check across the battery terminals. Should be a 12+ volts from your battery. 12.6-12.8V at rest is considered a full charge, will be more if recently connected to a charger.
While cranking (I pull the safety lanyard to make sure it won't start...DON'T START OUT OF WATER!) measure the voltage across the battery terminals. It should be somewhere around 12 volts or just below. If it is much lower than that, say 10 volts, then the battery is bad and should be replaced. If it is around 12 volts then leave the negative voltmeter lead on the battery and probe the starter. The voltage there should be 12 volts or so, not much lower. If it still hasn't started and the battery runs down again then feel the cables to the starter - are they hot? If so then the starter motor may be shot and is drawing too much current. If you can get a clamp-on ammeter then use it to measure the current draw of the starter motor. According to the manual, starter draw is 110-200 amps under load.
Hope this helps!
Brian
www.calledinsick.com