The facts: Brand new Kia Rio, everything seems fine. But very hard to start, sometimes doesn't start at all. After a lot of cranking, I start to worry, turn it off, wait a moment, try again. Then it starts. This leads to an hypothesis, which pans out: if it hasn't been run for a few hours, if I just try to start it, it won't start. If I crank it once, no matter how briefly, quickly turn it off, and then start it again, it starts right away.
Also, if I've been driving it awhile, and then turn it off, after a few minutes of rest, it will start quickly. It would *seem* as if it is having a hard time starting *cold* except for the mystery that it will start instantly if you do the trick: switch it on, then off, then on again, quickly--no matter how cold it is.
Initially thought it was fuel line, tried a gas additive, no change. Then thought it was the battery, but Sears checked it out--the battery passes all tests with flying colors.
I'm looking for an hypothesis, because the word from the dealer shop is "we won't fix it because we are unable to replicate the problem." He also said "sometimes it just needs a tap to the gas pedal." But it made absolutely no difference--I could crank as long as I like, give it as much or as little gas as I like, and it wouldn't turn over unless and until I shut it off for a second and then try again. And the second try always works--with no pressure on the gas pedal at all.