About a third of Atlanta school buses have defective engines, leaving students stranded or packed onto overcrowded buses, Superintendent Meria Carstarphen said.

“Most of our fleet is down, all the time,” she said.

The district is investigating how Atlanta Public Schools ended up with so many bad buses.

“I think we as usual got a really bad deal…or somebody had a contract,” Carstarphen said. “Something is really wrong there.”

Carstarphen spoke about the issue at an Atlanta Journal-Constitution editorial board meeting Thursday.

“There’s a third there and they all have the same engine and they’re junk,” she said. Most of the engines are in buses that serve the North Atlanta area, she said

Mechanics have rebuilt about 60 percent of the engines Carstarphen called defective. And the district plans to hire more skilled mechanics to work on the buses.

“We need like the Porsche people,” Carstarphen said.

The district spent $2 million at the end of last year to buy new buses —with different engines —and plans to spend another $16.3 million on transportation in proceeds from its next Special Purpose Local Option Sales Tax.