I started the boat, ran for 2 hours and when I got back to dock it would not start. This has happened twice now. It will not start now either at the house. After a while, maybe when I get home it will start. I can start it 5 times. But, when I go to the river and run for awhile it will happen again. The battery shows 12 volts, it read 13 volts while it was running. Please help.