Removal of zexel inj pump on 3ld1 engine

Hi As title, I have a ihi32j excavator with the isuzu3LD1 engine I have to remove the three zexel injector pumps. Do I have to do anything to remove them or just undo the four holding nuts and pull them out. I no on a Perkins the throttle must be in full,position. Not sure how these ones work p, they arson a rack system Ny help be much appreciated