A fresh setback for Boeing's space program.
The aerospace giant had to scrap a launch of its CST-100 Starliner to the International Space Station this week due to a system glitch after already delaying the launch last week.
Boeing said its engineers have ruled out a number of potential causes for a system glitch, discovered while making checks after electrical storms in the region.
Engineers are focusing on the propulsion system.
Boeing said additional time is needed to complete the assessment and ruled out Wednesday as a make-up day.
The delay of the uncrewed test flight throws into question the timing of Boeing's follow-on mission with a crew onboard, which Boeing has said would take place no earlier than December.
The Starliner space capsule has been problematic for Boeing. A series of software glitches during the December 2019 debut launch resulted in its failure to dock at the orbital laboratory outpost.
Since then, Boeing has spent time correcting issues flagged during NASA reviews.
Meanwhile, Elon Musk's SpaceX has sent three manned Crew Dragon missions to the space station since 2020, with a fourth mission scheduled for the end of October.