I NEED SOME HELP GUYS!

[sam's 72]

My step son has a jeep, straight 6 in it, he just called me said that it will not start!
Give you a quick run down on it.
It has gas in the tank.
Before this happen he said that when he made a quick stop the jeep would die.
When he backs up fast and hits the brakes he said the engine revs up fast for a sec.
He changed out the fuel filter, and the fuel pump thinking this was the problem. Did not help at all, this is a 85 jeep. It has a carburated engine.
Then he told me he pulled the filter again, and there was a lot of pressure built up and when he broke the fitting loose it sprayed gas out.
So with this said, I think the problem with it dieing out when he hit the brakes is the float needing to be adjusted. Man he drives this everyday, so it has not ben sitting at all, what do you guys think could be the problem?
Sam