Just a shot in the dark on the vac pump. There is a replacement part from a truck that GMC makes that will work....I'll look up the part number and post it for you when I get a chance...you have to change the plug on the pump as it is not the same as the set up in a ZR-1 wiring harness, but the pump is the same pump with a different P/N because it is from a GMC truck....oh, forgot this: a VW V6 Golf(?) or GTI(?)V6 uses the same pump also. It's a german brand pump, Bosch maybe???
Anyway, your pump may have stopped due to mositure corroding the pump motor. You can take the pump apart and disassemble the motor to clean it up and reassemble and it just might work....I did it to mine & so far it's been good. It's a really simple electric motor and simple wiring that will require some soldering skill to take it apart & reassemble. A little contact cleaner aerosol and some WD40 and some 1500 grit wet paper or crocus cloth and I used di-electric grease as a lube & moisture barrier is all you should need. My motor seized up & toasted the plug, which stopped the pump from working...and it didn't blow the fuse...I even got away with cleaning up the plug contacts and didn't have to splice in any new wire. Just a thought , if the fuse for the pump is good, unplug the power connection at the pump and look to see if it is semi-melted. If it is, chances are that the motor froze up from moisture intrusion.
Tom