backhalfeds10

i just bought my first zj on Friday and i am having some issues it is a 1998 Grand Cherokee Laredo 5.2 automatic with the 249J

Issue #1 There is a Evap pump i believe is what it is called in front of the washer tank right next to the air box that knocks after about 10 min of running it sounds like an engine knock but if you unplug it will stop. the check engine light was on when i bought it so i ran the codes and one of them was the evap system. so i look around and found the connection unhooked and now i know y they unhooked it because it is making sounds you can hear over the running engine. So does anyone know what would make it do that


Issue #2 The second code that i came across was an open circut on the number 8 injector the guy told me when i bought it that it was replace so there is a new #8 injector they had shaved the wires off around the plug i am guessing to test it and then electrical taped it. So i figured maybe it was shorting out so i cut the plug of and took it apart and re soldered some new wire on and soldered it back together. So i deleted the codes from the computer and started it and there was that dam check engine light again. so i checked the code and it was a open circut again. What the hell does that mean i checked the voltage on the injector next to it and it was fine then i checked the #8 injector and it went off the chart. If anyone can help me i would so appreciate it could it be a bad computer.