I have a Mercury 40hp bigfoot outboard 4 stroke on my pontoon boat. I recently replaced the waterpump, impeller and thermostat. Afterward, the motor produced a steady stream of water and I thought I was done. Yesterday on the water at about 4000 rpm the water pressure gauge read zero and the alarm came on. I am still get a steady stream of cool water from the engine. Is there a sensor that may need replacing that triggers the alarm or water pressure gauge? Any help would be greatly appreciated!
