Town Line Auto's suggestion is highly possible - sugared fuel. I drained the fuel and did not see anything unusual except the color which was a little darker than normal (leaded gasoline always had some red/brownish color). I took a sample of the fuel to be air-dried. It left a sticky film in the container. Sugared or not, I am afraid of old gasoline now. Better yet, most of my cars run on diesels and all fuel caps are locked.