To prove deficient or insufficient

• run out
• give out

To be unsuccessful

• bomb
• flop
• fall down
• fall through
• choke

To receive less than a passing grade

• flunk

To not do (something necessary)

• omit
• neglect
• default

To lose strength or power

• ?
• weaken
• waste
• wane
• sink
• languish
• flag
• fade
• deteriorate
• degenerate
• decline

To cease functioning properly

• conk out
• give out
• break down

To make or become unusable or inoperative

• bust
• ruin
• break

To undergo sudden financial failure

• fold
• go under
• crash
• collapse
• bust
• break

To be unsuccessful

• go-over-like-a-lead-balloon
• die-on-the-vine
• go on the rocks
• fold-up
• wash out
• strike out
• flunk-out
• peter-out
• conk out
• not cut the mustard
• come-a-cropper
• not come off
• draw-a-blank
• lay-an-egg
• touch bottom
• not get to first base
• go-up-in-smoke
• end in smoke
• go down swinging
• go-down-the-tubes
• crap-out
• hit rock bottom
• go-belly-up
• fizzle-out
• blow the chance
• bite-the-dust
• miss-the-boat
• fall down on the job
• flunk
• bomb
• flop
• go-wrong
• fall from one's high estate
• lose control
• miss-the-mark
• not make it
• not make the grade
• break one's word
• come short of
• be all over with
• not have it in one
• give out
• lose-out
• not pass muster
• not measure up to expectation
• not measure up
• miss an opportunity
• hit a slump
• lose one's labor
• go under
• go down
• be inadequate
• be deficient
• be found wanting
• be found lacking
• get left
• fall down
• go astray
• go amiss
• fall through
• fall flat
• come-down
• lose status
• be demoted
• not pass
• backslide
• neglect
• abort
• lose-ground
• get-into-trouble
• come-to-grief
• misfire
• founder
• run-aground
• break
• break down
• blunder
• flounder
• falter
• come-to-nothing
• come to naught
• make-nothing-of
• lose
• slip
• miss
• fall-short
• miscarry

To disappoint

• displease
• leave
• desert
• let down

To grow less

• sink
• worsen
• lessen
• decline

To become insolvent

• bust
• go on the rocks
• lose-one-s-shirt
• go-down-the-tubes
• go-belly-up
• crash
• drown in red ink
• be unable to make ends meet
• throw-in-the-sponge
• go-to-the-wall
• fold
• go broke
• collapse
• be ruined
• repudiate
• dishonor
• default on payment
• go under
• go into receivership
• go out of business
• overdraw
• be in arrears
• default
• go-bankrupt

To dismiss for failure

• send-down
• flunk
• put on probation
• suspend
• dismiss
• send home