Could be low enough on coolant that the temp sensor in the thermostat neck is not down in the coolant being it's mounted at the highest point of the system. With the engine cool, I would take the cap off the neck( under right side cover in front of the tank) and add coolant. There is an air bleed valve on the thermostat housing by the temp sensor. Takes a 10mm boxed end wrench. Get ALL the air out. You can pour in coolant all day long but if you don't open the valve you will have trapped air in the system. Fill the coolant full, run the engine up to normal temps, let it cool down and repeat filling steps. Best to loosen the tank and you can just tilt it to the left side just enough to get to the valve. This engine do not like the least bit of air in it's system. It's only 1 1/2 quarts coolant system plus whats in the reservoir. Takes very little in lacking coolant to heat up these engines. Be sure to use a non silicate antifreeze in these engines.
Last edited by Chuck A.; 06-28-2013 at 12:08 PM.