I bought my VX this summer and it has worked perfectly. Now that colder weather has moved in I find I have a problem. The VX starts and runs fine until the temperature drops below freezing. When I try to start it, the engine turns over fine but it will not fire. I have replaced the battery and run several bottles of Heet through it but it hasn't done any good. Is there some kind of a sensor that may have gone bad? Before I go to a dealer like a hog to slaughter & end up paying $500.00 for a mysterious part I wanted to ask you experts.