My oil furnace is running and blowing warm air but while the blower is running the burner seems to be cycli g on and off. Its never done this before and not sure shere to startcould it be a clogged nozzle water in the oil or something else thanks for any help. Well since posting my question several days ago with no help in sight I changed the filters and nozzle. It is doing it less frequently but still doing it.