I agree with Dan, your explanation is missing a few details which would help solve the issue....In any case, here's a little story I'd like to share.....
A couple of weeks ago I went to turn on my '79 911SC, and it wouldn't start. The starter would crank, but that's it...the car wouldn't start up. I immediately thought it was fuel, since the starter was cranking, but I wasn't going anywhere.
I decided to check for fuel by disconnecting where the fuel exits the fuel filter. Once I cranked the car, fuel immediately gushed out. I figured the test I had just performed cancelled the possibility of a problem with the fuel pump and filter. At this point I started to doubt fuel as my problem.
I therefore checked for spark. I did what Superman explained and noticed that I did have a blue spark jumping from plug to ground.
At this point, since both fuel and spark had passsed the test, I was confused and handed the car over to the shop for a more detailed investigation.
The next day, I found out that my problem was a combination of Coil, and a so called ??? Unit (square metal box located between the rear fuses and fuel filter....some of you techies may know the name
) I had both the coil and the Unit replaced, and am now running stronger than ever!!!
Anyway, I know the 911 in question is a few years newer than mine, so not sure if my $0.02 will help, but thought I'd share just in case.
jam