I have a 2019 sun tracker sport fish xp3 with a 2018 mercury 150. While out on the water the alarm sounded on the engine. Stopped engine trimmed up to make sure nothing was stuck to the water inlet. Nothing was. Started engine again and started back down the lake alarm sounded again and engine was pulsing. Engine is a 4 stroke and at this time isn’t quiet any longer. Oil level is not low. I don’t know what it could be. Engine hrs are 43. Any ideas would be appreciated thanks