Keshia Knight Pulliam -- Ed Hartwell Hasn't Paid Me ... Lock Him Up!!

Keshia Knight Pulliam is accusing her estranged husband, Ed Hartwell, of not ponying up money he agreed to pay her ... now she's asking the court to find him and lock him up until she gets it.

Keshia claims she and the former NFLer signed an agreement shortly after he filed for divorce ... which required him to cut her a check. She says it never happened, despite repeated attempts to collect.

According to the docs ... the amount she's supposed to get is confidential, but she's so pissed she wants Ed behind bars.

This breakup's already had nasty paternity issues and claims of emotional abuse -- so time is obviously not healing any wounds.