Take boat to lake start up head across lake at 25mph or whatever that is in knots. get going pretty steady motor just dies. Won't restart has done this twice has something to do with ignition. Let it set a day or so starts does it again.I know this not much info but would appreciate any suggetions, mechanic says he can't figure it out. Seems like some part is getting hot and then shutting down. Has new points cap and rotor, but no spark after it shuts down.