What was found
PHX - SMOKE - AFTER ALL THE PASSENGERS HAD BEEN DEPLANED, SMOKE WAS REPORTED COMING FROM THE APU TAILPIPE. EMERGENCY EQUIPMENT WAS DISPATCHED. MAINTENANCE INSPECTED APU TAILPIPE AND FOUND NO DAMAGE. MAINTENANCE FOUND TANK VENT LINE DRAINS (AFT ONE) NOT ALIGNED WITH DRAIN RECEPTACLE. ADJUSTED TANK DRAINS SO ALL LINES ARE ALIGNED. DRAIN SYSTEM NOW DUMPING EXCESS FUEL INTO DRAIN TANK AS REQUIRED. OPS CHECK OF APU WAS GOOD.