This is going to sound strange but i was going to follow your idea to check the voltages on the key switch in start...in process of taking key switch out of dash, two wires popped off the back and I could not see which was for which post. I guessed. First way, my symptoms remained as above. I decided I had nothing to lose by swapping the two wires, one was red with white and the other was two reds paired together. After I swapped them, the bloody boat fired...i installed the fake a lake, and 5 seconds later I was idling for the first time. Eureka!! I wasn't really getting water out the exhaust, so thinking maybe my water pump is stuck...thinking I might toss it in the lake this week to see if the additional pressure lets the pump turn as it should.