He has now scored five goals in his last six appearances which makes him one of the most prolific strikers at the present time.
His partnership with the rapidly improving Clinton Morrison has also contributed to this sudden surge of goalscoring.
As a result Birmingham were able to chalk up their first win in four cup games against Leeds with Morrison having a hat-trick of assists.
As a result, the long running Robbie Savage saga was put on the back-burner and was not allowed to overshadow Birmingham's performance which was a credit to some positive play from the likes of Darren Anderton, Morrison, Heskey and local favourite Darren Carter.
Leeds were rocked by Heskey's first goal and the booing of the recently recalled Michael Duberry by his own supporters hardly set the tone for a possible upset.
Duberry, in fact, only lasted 24 minutes before exiting the game with a hamstring injury. Not before being at fault for the second goal however.
Before the game Leeds' coach was followed to the ground by a fire engine, but it was Birmingham who put out their fire with some clinical finishing.
Birmingham boss, Steve Bruce, who has mixed experiences of the FA Cup, was quietly pleased with the outcome and particularly the two-goal performance from 21 year-old Carter.
Leeds, twice beaten by Birmingham last season, are a pale shadow of their Premiership days and their rapid fall from grace is a stark warning of how quickly a club can fall when financial problems occur as a result of bad management.
Just how far Leeds have gone back was highlighted by Birmingham's ability to carve out such a commanding lead early in the game which was virtually over after the opening 25 minutes.
The power of Heskey was a key and the in-form striker was in top form to open Birmingham's account in the eleventh minute when he finished off a fine move with a classic shot which went in off the post.
Anderton was the playmaker with a fast, hard low pass to Morrison who slipped the ball into the path of Heskey to finish in style.
It was another occasion when everything went against Leeds as they painfully discovered to their cost when Nathan Blake was stretchered off with a leg injury.
Matters could only get worse and for Leeds' noisy fans they had to suffer a second goal in the 22nd minute when Anderton again began the move with a pass to Morrison who, on this occasion, slipped the ball to Carter to notch a simple goal from just outside the six-yard box.
There was no way back for Leeds as they were generally off the pace, but they still had opportunities but there was no real conviction about their play.
Early in the second half Frazer Richardson had a good opportunity, while Aaron Lennon failed dismally to make a clean contact with a left-wing cross with only Maik Taylor to beat.
They were put out of their misery when another accurate pass from Morrison to Carter in the 65th minute produced the third goal.
Although replaced after 61 minutes by recent signing Robbie Blake, Heskey put in a performance that gave a reminder of his undeniable ability.
Leeds haven't beaten a higher-ranked team in the Cup for 18-years and, though only a fight for financial stability and survival in the Championship beckons, they should take comfort from a brave performance.