The launch, a test of NASA's plan to let private companies conduct space missions for the agency, is now set for 3:44 a.m. EDT Tuesday, the Los Angeles Times reported.
"During rigorous inspections of the engine, SpaceX engineers discovered a faulty check valve on the Merlin engine," said SpaceX spokeswoman Kirstin Brost Grantham in a statement. "The failed valve was replaced on Saturday and after thorough analysis the vehicle has been cleared for launch."
Just minutes before the scheduled launch at 4:55 a.m. EDT Saturday, a flight computer detected an anomaly in one of Falcon 9 rocket's nine engines and automatically shut down the launch sequence, SpaceX said.
The California company is launching its Dragon Space capsule on a mission planned to see it dock with the International Space Station, to become a way to haul cargo to the station following the retirement of NASA's space shuttle fleet.