what does it mean "when james laughed,he sounded like a car trying to start"

This is a relatively simple simile in which the character's laugh is compared to a car which is trying to start. The very trying hints at the idea that in the same way that the car does not get started the laugh does not quite get started. In some ways, the idea might be concluded that James either does not know how to laugh or that he does not ever quite "get the job done." This quote would have to be put in the entire context of James' character to be fully meaningful.