i have a 93 pontiac bonneville 3.8 liter series 2 supercharged and the boost gauge sits at negative at all times and when i throttle it hard , the gauge barely moves but remains in the negative.i know its supposed to be at zero(vertical).so what could be the problem ? i have no vacuum leaks.

You do not have a Series 2, it is a Series one. As for the the boost gauge, it is supposed to sit in the negative and float around depending on how hard the throttle is pushed, at WOT, your needle should sweep over into the yellow on the gauge. As for the problem, I am betting on a bad BCA or BCS, but I think the BCS will trip a SES. Let the gearheads explain it.

Do a simple test. Pull the vacuum hose/elbow off the bottom of the BCA (round black cylinder). If your boost doesn't return like it should, I wouls strongly suspect the BCA if you really don't have any vacuum leaks.

Any update?

So with the key on and the engine off does the guage read negative or 0?