While out fishing's I looked at my gauges and the temperature gauge had jumped to 200. The oil pressure was reading about 10 lbs and the voltmeter was below 12 volts. Then the temperature would jump to 220 degrees and the oil and volt would drop at the same time. This was happening about every minute or so with all the gauges acting as described above. I checked the engine in several places with an infrared thermometer and the highest reading was around 170 degrees. When I first bought the boat the owner had told me that he could not get the engine temperature above 150 degrees on the gauge. This seemed true until it started reading 170 degrees last summer. Now I need to know it I should replace the temperature sensor or the thermo monitor or both or the temperature gauge or ? I turned the key on today and all gauges read zero. Any help is greatly appreciated.