An MD88 flight crew's failure to accomplish before takeoff checklists with care resulted in a takeoff with the cabin pressure controller in the manual vice automatic mode and contributed to their eventual failure to regain pressurization control. The flight returned to the departure airport.

Narrative

The initial part of our flight was very busy; with a lot of adverse weather around the airport and on our route of flight. After takeoff; there had been deviations for weather around the airport. Passing approximately 8-9000 feet; we received clearance to climb to 13000 feet. Shortly after passing 10;500 feet; we got indications that the cabin was not pressurizing. We requested and received a clearance to descend back to 9000 feet. A check of the flight deck showed that the cabin outflow valve was in the manual position. We repositioned the valve to AUTO (the correct position for flight); and observed that the outflow valve did not move toward the closed position. About this time; one of our flight attendants toward the back of the aircraft called us; and told us that her door was making a loud; rushing air sound; and that she could see light through the door seal. After several minutes; the cabin remain unpressurized; as confirmed on the cabin altitude gauge; and the cabin outflow valve wasn't moving toward closed. We accomplished the appropriate checklist procedure for cabin not pressurizing; and returned to our departure airport for landing. Emphasis on checklist discipline could have prevented the initial part of the situation; caused by taking off with the cabin outflow in manual. Once the outflow valve was in the proper position (AUTO); it appeared to us that there was an aircraft malfunction; because the cabin altitude gauge was matching aircraft altitude; the outflow was not moving toward closed; and one of the flt attendants was telling us about a leaking aircraft door.