Gear will stay meshed with other gear, locating pin stays in gear also. Just need to remove 3 bolts that hold gear to pump drive hub. Pump can be removed/replaced without regard to timing, just use scribe mark on pump flange to align with timing cover mark, can't go back wrong as locating pin in gear enters groove in hub. DO NOT remove allen screw in hub center as this must stay with pump. Had a pump awhile back that owner removed that way, he had to make another trip to bring me the hub so it could be assembled correctly. Also leave both stop and throttle levers on pump too, have made service calls to install them after someone couldn't get them on right.