Have you followed my B-52 Driver engine start post HERE. If you follow that exactly, you might get them started.

I have found that, for some strange reason, I need to pull the throttles backwards (it's like pulling them into reverse, except that it is the fuel cutoff position) using F2, return them to the throttle stop position using F1, and then moving them just a small amount forward using F3. My engines DO NOT START unless I start them that way.

Hope this helps.

Mark