A cooperative research and development program was organized to determine the critical particle size of abrasive debris that will cause significant wear in rotary injection fuel pumps. Various double-cut test dusts ranging from 0-5 to 10-20 μm were evaluated to determine which caused the pumps to fail. With the exception of the 0-5-μm test dust, all other test dust ranges evaluated caused failure in the rotary injection pumps. After preliminary testing, it was agreed that the 4-8-μm test dust would be used for further testing. Analysis revealed that the critical particle size causing significant wear is 6-7 μm. This is a smaller abrasive particle size than reported in previously published literature.A rotary injection pump evaluation methodology was developed. During actual operation, the fuel injection process creates a shock wave that propagates back up the fuel line to the fuel filter. Using the injection pump as part of the fuel filter evaluation incorporates the vibration and shock wave seen in the field. Limited test data indicate the ability to repeat this methodology. A comparison between a current SAE procedure and the developed procedure reveals drastic differences in the fuel filter efficiency.