When we were Looping, the engine would occasionally just shut down with no warning. The engine display would say "Emergency Stop Activated - Reset Emergency Stop Button." I would shut everything off and restart the engine. After this happened a few times (and it was indeed scary), I found that it only happened at about 2200 RPM. We did not often travel at this rate, usually when absolutely needed like when going against currents...like going upstream in the Point Pleasant Canal, where it quit while going under the bridge by the Cop Shop, or in a strong crosswind in the Monument Channel in Georgian Bay in 100 feet of water and 100 yards from the shoreline rocks. To make a long story short, a very bright mechanic, while changing out the emergency stop switch that we thought was the culprit, noticed that one of the engine mount nuts was missing...he recovered it from the bilge and put it back on. The other three were still tight. He theorized that without that mount nut, the engine would vibrate at the right frequency to engage the stop switch, which is a mechanical button, hence the problem only at a certain RPM. We now have about 400 more hours and this problem has not recurred. Engine mount nuts are important.
