This study addresses the contamination sensitivity test of a typical fuel pump for automotive vehicle. The objective of the study is to find the contamination sensitivity coefficient of fuel pump on specific contaminant particle sizes so that optimal fuel filter could be selected. To achieve the objective, the degradation of discharge flow rate of fuel pump was measured under the experiments of various contaminants size ranges of ISO test dust up to 80${mu}{ extrm}{m}$. The fundamental theory of contamination sensitivity was introduced and the contamination sensitivity coefficients were estimated using the experimental data. Maximum contamination sensitivity coefficient of $5{ imes}10^{-6}$ L/minㆍEa was found on the contaminant size range of 40${mu}{ extrm}{m}$∼50${mu}{ extrm}{m}$. The magnified picture of the surface of vane disc revealed that the abrasive wear was the principal cause of discharge flow rate degradation. Hence, this study revealed that high efficiency filter on the contaminant particle size range of 30${mu}{ extrm}{m}$∼70${mu}{ extrm}{m}$ especially should be used to maintain the service lift of the fuel filter.