If you have enough water in the bilge for the crank pulley to sling it up on the motor then the first thing you need to fix is how that much water is getting in. Had my Sanger three years and never more than 1/2" of water in bottom from like 2 weeks of house boating. Sounds like your packing nuts need to be adjusted to slow water intake. I would look at the cable from motor throttle body for kinks or chafe points make sure cable slides easily in the housing. Next make sure throttle body operates smoothly and easily. Unless the motor shows signs internally of corrosion than I would say that something is overloading the servo causing it to overheat and fail. http://www.perfectpass.com/troubleshooting/Trouble.Mechanical.pdf
This test should confirm whether the PerfectPass throttle cable & linkage
connection is properly working.
With key OFF, push the manual throttle to 1/2 open position. Now take black
knob on servo and slowly turn the knob in a counterclockwise direction, and then
in a clockwise direction.
As you rotate the knob back & forth, you should see the throttle lever on engine
opening & closing very smoothly with each step of the motor. As you turn the
knob counterclockwise, which lets out cable, the throttle will close back towards
neutral. When you rotate it clockwise the throttle will open.
As you rotate the knob back and forth (slowly and quickly), the throttle should
open & close very smoothly and the brass L Adapter at linkage should be rotating
as well to follow cable. At no point should the throttle cable catch, hook or come
into interference with any part that could disrupt the cable movement.
If the cable is rubbing against a decorative engine cover, fuel rail, motor box etc,
adjust servomotor and cable to improve alignment. Many plastic decorative
engine shrouds can cause this problem. Remove temporarily and run boat if you
suspect this could be a problem.
Final Test: With key OFF, push manual throttle to full open position. Watch
PerfectPass throttle cable to ensure it can move freely without binding or