Think-aloud pair problem solving (TAPPS) was used to formatively assess agriculture students' problem solving during compact power equipment troubleshooting training. A total of 56 students were taught engine operational theory and a troubleshooting procedure followed by training in TAPPS. Prior to troubleshooting a pre-test engine operation theory knowledge test was given to students. Students were then asked to troubleshoot a single cylinder overhead valve Briggs and Stratton engine which had a system fault involving insufficient valve clearance, spark plug gap clearance, or insufficient fuel delivery to the carburetor. Each student was randomly assigned to individually troubleshoot one of the three faults using either TAPPS or by working alone. To standardize the question prompts used during TAPPS, the listener role was performed by an undergraduate researcher. Only 66.1% of students were successful at identifying and repairing the fault. The chi-square test of association showed no significant difference (χ2 (1) = .08, p = .78, phi = .038) in success rate between students who worked alone and those who used TAPPS. A review of video recordings of TAPPS sessions revealed unsuccessful students stated feeling unfamiliar with valve clearance adjustment procedures, forgetting possible faults, lack of understanding compression gauge operation, and connecting engine theory of operation with troubleshooting. TAPPS served as a way for the instructor to identify student misunderstandings to inform individual instructional interventions to improve students troubleshooting skills. Suggestions for instruction included memory association exercises to help students linking engine components with possible faults.