I recently bought a 2000 gmc z71, origionaly a 4.8 it now has a 5.3 catless exhaust, 35s and 4.56 gears. The previous owner put a new fuel pump(from auto Zone) in the truck right b4 i bought it, it is hard to start nearly all the time, you have to let the fuel system prime b4 it will start, and sometimes after it fires up it almost chokes like its flooded which leads me to be leave it is something other than the fuel pump, i put a new regulator on it and does the exact thing, any help greatly appriciated.