I believe that it is the thermostat that tells it to turn off when it reaches the right temp. So in the case of your coffee percolator I believe that it doesn't reach the right temp to brew the coffee. Check it with a cooking thermometer(digital works best)and run the pot through a cycle but don't add any coffee. Once done, stir the water in the pot just enough to get an accurate temp reading. The temperature of the water should be at least 185 degrees. Hope this help with the java....;-)