PA-32 pilot reported they realized the main cabin door latch was not secured during departure and when returning to the airport they switched fuel tanks to an empty tank causing the engine to lose power so they landed on the nearest suitable runway.

Narrative

During departure from ZZZ; it was discovered that main cabin door upper latch was not fully secured. A power reduction was made upwind to crosswind and radio calls were made to local traffic that we were returning to land in the pattern. During downwind time base; the engine surged and lost power. I immediately turned to the Runway XX numbers. I was unable to restart the engine; though it continued to surge and run in some capacity until touchdown on an abandoned runway. I broadcasted a mayday call in the blind and announced intentions to land on an abandoned runway surface since altitude did not allow a landing on the main surface. No lights were hit; no damage was found on the airplane; and no conflict to other traffic presented. On rollout; the engine quit running. I determined that the fuel selector had moved from one main tank that has 18 gallons of fuel to another main tank that was empty; either during take-off or during the door security. I switched tanks on the abandoned runway; started the engine and taxied to the main apron. I shut down and thoroughly inspected the aircraft. I adjusted the upper door latch on the main door with hand tools. A verbal report was given to the airport manager. No additional information was requested and I started my aircraft and continued on my journey.