I ran out of propane and now the water heater pilot light will not stay lit
I have had similar problems in the past when running out, what I found is I had to hold the pilot for several minutes to get the lines full of propane again. I found it easiest to light the stove top or try until it would burn then I went to the furnace and water heater it still took a few minutes as the pilot is a very small draw but once the lines had properly purged I had no problems after that, it was like some air was in the lines would light burn funny and go out, once I got a solid flame the problem was solved.