This is the necropolis hotel section of the map of the wasteland presented by:
The sewers can be acsesd by the manholes. From here you will need to go north, by sewers. ALWAYS check every inch of the sewer for bodies that contain items and hidden items on the floor. Also there will be rats so you will want to kill them for some extra Exp. You will come across a gang of ghouls in the sewer. They unlick the other ghouls will not attack you, they will mearly say: "Don't shoot". Talk to the leader of these ghouls and convince him that you will not take the chip, but fix the the old pump so you can take the chip. The parts for the pump are found in the most northern main sewer ( all of the maps link from top to bottem, left to right ) , to get to it you must come out of the sewers at the water shed and infront of harry the super-mutant there is a nother sewer-hole. The pump is in the water shed. If you don't have a good repair skill you can take the junk to the underground ghoul leader and he will give you some books that should fix that up good.