Well... if it's a dead axle... then its probably exactly like mine was, when I got it, minus the decal on the deck and the scrub brakes... mines/was a 'Red Fox'... its altered some...
It's a good starter kart forsure!... word of caution... watch your right turns(too fast and you could end up w/ some pavement tats.
... and as for u hitting a bump n it dieing on you(seeing that noone else has spoke up ...yet)... it does seem odd that it only dies on lower fuel n not a full tank. I was gonna suggest pulling the kill switch wire n drive it w/out it connected, n see if it still cuts off. Not sure how the wire goes on yours... but mine ran under the seat, n got pinched afew times, n caused the same problem... but it did it erratically... couldnt hurt to try. If it's not that... then im pretty sure someone will chime in w/ other possibilities.
So what are the details about your kart?... history, ratio(gearing)/motor, plans for it(if any)?