Mercruiser 3.0 Dead When Hot

[Roadblock007]

1991 Bayliner Capri with 3.0L Mercruiser and Alpha 1 Gen 2 outdrive.

Had the boat out last year and this year and all of a sudden on the lake this past summer it wouldn't start when hot. Won't even turnover. It's like I disconnected the battery, but all of the accessories work just fine. At first I thought it was the 50 Amp breaker because the first time it happened I pushed it, it seemed to go in a bit, then it started. With it not even turning over I wouldn't suspect the coil. My money is still with the breaker. Looks original. Any thoughts?

 

[alldodge]

My first thought is the slave relay.
Should get 12V when key turns to start on the lower small yellow/red wire. If you jump across the top 2 terminals, this will engage the starter

 

[Scott Danforth]

in addition to the slave/pilot relay. the wire that feeds it will be yellow with a red stripe. the yellow/red stripe wire will have 12 volts when the key is in the start position.

check all your connections. could also be a bad battery or ground connection that opens when warm.

all your cable connections from the battery to the starter and back should be clean, shiny and tight

another thing to check would be to make sure your neutral safety switch is operational and that your key switch is actually producing 12 volts in the start position on the S terminal

 

[Roadblock007]

Thanks guys. I know I asked this months ago but it was while the boat was winterized. I will get on it soon. The weather is warming up!