Guy Whittingham praised his side’s resilience, yet Pompey still slumped to the foot of League One.
The Blues fell behind to Rory Loy’s 51st-minute strike, while Jon-Paul McGovern struck the post with a free-kick in the first half for Carlisle.
Pompey, though, fought back to level in the 78th minute through substitute Liam Walker’s penalty.
However, Hartlepool’s last-gasp victory over Leyton Orient means Whittingham’s men are this weekend bottom of the table.
The caretaker boss said: ‘A few weeks ago we would have lost this game after coming from behind.
‘But the guys stuck at it, they kept on going and in the end Liam scored with a very coolly-taken penalty.
‘It’s a second successive draw, which we will take, and we’ll just carry on trying to be hard to beat and getting points.’