Hi, If the engine is turning then the electrical supply to the starter etc is good. The attached photo shows a close-up of the pump. On the forward side is the control to stop the engine. Ensure that it is fully turned anticlockwise. Look at the securing nut on the top of the arm. Is it tight? If it is loose it is possible that the arm is moving on the spindle. Although the stop control my be fully 'in' its possible that the pump is still in the 'stop' position. Ensure that the spindle is located correctly in the arm and nip the nut up.
Check the throttle arm likewise and nip up the nut if it is loose.
DavidP, South Wales