A plug-in pump, which is controlled by a beveled edge, is inserted in a pump installation bore of the internal combustion engine with the aid of an adjusting arrangement and ensures a uniform feed quantity in all plug-in pumps of an engine without subsequent feed quantity adjustment. When the feed quantity adjusting element is fixed in the testing position, the plug-in pump, which is inserted in the test base, is rotated until the feed quantity corresponds to the desired feed quantity and a positioning peg of the adjusting arrangement, which is supported in the flange of the plug-in pump and received by a recess in the test base, is adjusted and fixed in this rotational position. When the control rod of the engine is blocked in the basic testing position, a positioning groove (33) of an adjusting plate (32) of the adjusting arrangement is put into a corresponding rotational position by means of a pump dummy.