Random starting problems

[binaryc]

I've got a '99 Boxster, and every once in a while I have a problem getting it to start. The starter motor spins strong, but it just won't light. I've ruled out the battery by connecting another battery from a different car. I'm not getting a CEL or any fault codes.

The only way I've gotten it to start is to just keep trying. I normally crank for a few seconds, then let it sit for a while for the starter motor to cool, then try again. Eventually it'll start. Once it starts, it runs smooth. I'd guess it has the problem once every five starts or so. The only consistent theme is that it happens at the most inconvenient times.

I have a feeling it's not a spark problem, or I'd have running problems as well (and probably get a code). My guess is may be a fuel pump problem, but I would imagine I would also get running problems (and a code), wouldn't I?