This study investigates the influence of key process parameters on the tensile strength of ABS-carbon fiber composite parts fabricated using the Fused Deposition Modeling (FDM) process. Four parameters were considered, namely layer thickness, layer orientation, extrusion temperature, and printing speed. The Taguchi design of experiments was applied to efficiently reduce the number of tests while systematically evaluating the effect of each parameter. Tensile specimens were produced according to the ASTM D638 Type I standard and tested using a universal testing machine. The results showed that layer orientation and layer thickness have the most significant influence on tensile strength, while extrusion temperature and printing speed also have a notable but less dominant effect. Aligning the printed filaments with the load direction and reducing the layer thickness enhance interlayer bonding and lead to a significant improvement in mechanical performance. These findings provide valuable insights into the relationships between process parameters, internal structure, and mechanical properties, and form a solid basis for optimizing the FDM process to improve the quality of printed parts.