Have Boat Questions? Ask a Boat Repair Expert.
Hi Joel, my name is Jason.
The slow turning cover can be a bad battery, low voltage to the starter, or a bad starter. Do you have a voltmeter and do you know how to take voltage measurements?
At one point they made a wiring harness but it won't be available if the boat is an 86. Somebody good with electrical would have to go through it. The engine should be spinning over quickly with 9.5V if its not, the starter motor is going to be bad.