Stuart Taylor's side were left frustrated and ended the game with 10 men as UCD took their chances to record an important win at Thomond Park
Limerick took just three minutes to take the lead, with Craig Curran scoring from the spot after being taken down in the box by Gareth Matthews. Curran got up to squeeze the ball past Ger Barron, who dived the right way, but could not reach the goalbound effort.
At the other end, Dean Clarke got into a good position to curl the ball in, but was denied at the last moment by Patrick Nzuzi's goalline clearance. However, Clarke didn't have to wait too long to get his name on the scoresheet as he equalised from close range on 25 minutes by turning in Sean Russell's off-target effort.
The Students took the lead just before half-time after David O'Connor prodded the ball into the net against the run of play. Limerick were on top for large parts of the second-half, but could not turn possession into chances, with the standout moment an offside call on Danny Galbraith after Michael Leahy passed it back to Barron.
In a rare UCD attack, Leahy was denied by Ryan after a clever free-kick from Craig Walsh. Limerick continued to press, but a quick counter saw the Students grab another as substitute Cillian Morrison blasted in from range.
The Shannonsiders were reduced to 10 men in stoppage time as Shaun Kelly was sent off, while the Students' victory helps them keep their hopes of safety alive.