Many students enrolled in university physics have little interest in the subject matter, a trend more pronounced in females. This study assesses students' conceptual understanding and interest during the electrochemistry unit of a physics course for nonphysics majors that was revised in light of consistently low ratings from its students. The intervention, designed to improve the tutorials in a large lecture-based physics course, improved interest in the topic for which the new tutorials were implemented. However, no effect was seen for conceptual understanding, and the gender gaps persisted. (Contains 2 tables.)