The rack is controlled by by the gov. spring, the fly weights and the hand throttle up by the operator. You could have an inj. pump that.s tight in the bore in the pump from rust or setting for a long spell.Pull the throttle on and then see if you can force the rack back by hand with the side cover off the inj. housing where the pumps are. Work the throttle off and on and see if the rack travels free by watching it through the side plate (cover) hole.On later engines but not yours there is a rack limiter that only lets the rack travel far enough to let the engine start till it gets oil pressure up and then gets out of the way so then you have full travel of it.