The incident happened at 7:27 a.m. just south of Exit 8 in East Windsor Township.
Authorities say the fire started in the engine of the box truck. The driver noticed smoke coming from under the hood, pulled over and tried to put the fire out with an extinguisher but was unsuccessful.
The truck was carrying oxygen and acetylene, as well as welding equipment. Due to the material in the tanks in the back of the truck, both north and southbound lanes were closed for a time.
Northbound lanes reopened at 7:47 a.m. and all southbound lanes reopened by 9:20.
No one was injured.