on the right side of the motor (when looking towards the back of the boat) there is a sensor that threads into the block. i always pull it to drain the block. It is rather large and takes a pretty good size wrench. That sensor needs to be plugged in and the connection between the sensor and the block has to be solid. you cannot use teflon tape. I dont know what that sensor is (i think possibly a knock sensor) but if its not plugged in that motor won't run. it is possible that it is loose or corroded or a wiring issue. i would try that.