1
general::
Delay, as in The advertising campaign is hanging fire until they decide how much to spend on it. This expression originally referred to the 17th-century flintlock musket, where the priming powder ignited but often failed to explode the main charge, a result called hanging fire. [c. 1800]
American Heritage Idioms
2
general::
Phrase(s): hang fire
to delay or wait; to be delayed. • I think we should hang fire and wait for other information. • Our plans have to hang fire until we get planning permission.
McGrawhill's American Idioms And Phrasal Verbs