Just spent the last couple of days trying to get my 1999 996 fired up. Since i did not hear my fuel pump kick on I figured check the two fuses located under the tail.  After confirming they were good I was thinking pump or wiring.  Well after pulling the tank multiple times checking connections I decided to check the relays also under the tail.  Swapped them with some generic 5 prong ones and bam! she fired right up! One would think if the fuses were good going to the relay they would be good too. Turns out that the Bosch relays are prone to going out.  Oh yea and they will still click when you turn on the ignition leading you to believe they are good. So just incase any others experience this problem you can fix it in minutes.