If I remember correctly, to start up old fighters such as F-4s, you need an ASU but it looks new fighters do not need an ASU. Today, I was watching this video. It's a so cool video to know how new fighters start their engines. From 2:38, something starts and make a sound just like woooooooooooooooooo... you think a wolf is howling. From 3:06, the sound becomes stronger but, the question is what kind of starter is used by P&W F100 that makes such a sound?
Another figure of the intake and exhaust of the JFS from bottom of the fighter:
The below figure shows the danger area of the JFS:
And finally here is an image of this JFS:
Hope this helps.