need ideas for a 12v, vacuum engine kill valve
 

i put a mb 617 in my 98 tj and ive been using this vacuum change over valve that works fine, but it has a constant vent when the switch is closed, engine running. the problem is im wanting to run an electric vacuum pump from and Audi but the damn thing runs all the time due to the constant vent. basically the switch has 12v/gnd, 2 ports and a vent. while the switch is closed, the ports are blocked and port 1 just sucks thru the vent. key off and the ports are unblocked and vacuum is pulled on the injection pump. in about 5 minutes, the vacuum bleeds off and i can start the engine again. i can hook the ports up opposite, but it takes forever to bleed off. just wondering is there is anything else i can use