To misfire a gun means to fail to fire it properly. To 'misfire' in terms of a plan or project means to fail to produce the intended or desired result. A misfire (noun) is a failure to fire a missile or gun correctly.

1. The police officer aimed his gun at the armed robber and pulled the trigger, but nothing happened. The gun misfired.
2. We took a few financial risks which misfired over the years and put us in debt.

1. Claire has had a few misfires over the years, but generally speaking her plans are well-thought-out and successful.
2. I started my speech at the conference with a joke to lighten the mood, but it ended up misfiring badly. I think I offended quite a few people.