I have a 2000 Merc 4 stroke 50 hp bigfoot.<br />Serial # 0T008360<br />Model # 1-F50452Wd<br /> 50ELPT-4S<br />I keep getting an alarm after a 5- 10 minute run after I throttle down in about 30 seconds to trolling speed just barely above idle.<br />I have a good water stream as in the past years<br />I just replaced the water pump impeller,Thermostat<br />a 60 Centigrade, and the oil pressure sending unit.<br />Still I keep getting this alarm. The Motor is a carb model, 4 total. Fuel filters both on my engine and an extra that I installed in the fuel line between the gas tank 6- gallon and the motor are new.<br />The engine runs fine at High rpms it's only at slow or trolling speed that I have a problem.<br />I even removed the thermostat and still the alarm sounds.<br />I'll Shut the engine off and restart,Accelerate and no problem exists until I go back down to trolling speed.<br />When I replaced the water pump impeller no scratches or nicks were in the cup and top/bottom plates.<br />Any input or similar experiences would be appreciated.<br />nogimmies
