Northampton, lying just outside the play-off spots, came to Hull with only one aim - to win - and the Tigers never really recovered from the Cobblers' explosive start.
They took the lead in the third minute after a mistake by Joseph let in Richards, who ran clear of the defence and hit an unstoppable 20 yard shot into the top right hand corner of the net.
But his over-exuberant celebrations, which led to some Cobblers fans spilling out onto the edge of the pitch, earned him a yellow card.
But just five minutes later, City were level when Elliott picked up the ball outside the area, spotted the keeper off his line, and scored with a clever chip.
After 17 minutes, a long range shot from Burgess was well saved by Harper.
But a bit of luck helped Northampton regain the lead after 22 minutes when Sabin inadvertently scored from eight yards after the ball had ricocheted off his legs.
After 32 minutes the Cobblers extended their lead after Sabin's pace undid the Tigers defence and he shot into an empty net from about 18 yards out on the right.
The Tigers came out looking a little more composed after the restart with Delaney shooting over from a good position 18 yards out with Harper nowhere.
Northampton took off Sabin in the 63rd minute, and reshaped defensively in a bid to close City down completely and protect their lead.
But with half an hour to go the game exploded into life when City were awarded a free kick 25 yards out in a central position. Dawson stepped up to curl a brilliant effort into the top left hand corner.
Taylor missed a golden chance to extend the lead from just eight yards out as City began to really press, and Green saw a shot hit the left-hand post but it was not to be for City.