A system for combusting volatile vapors includes a carburetor having intake valves for receiving base fuel from a fuel source, ambient combustion air, and volatile vapors from a vapor source. A plurality of sensors measure and generate sensor data based on a respective plurality of physical properties associated with the carburetor and associate combustion engine operation. One or more programmable controllers receive the sensor data and control the intake valves to regulate respective ratios of the fuel, air, volatile vapors drawn through the carburetor based on the received sensor data. To increase the burn of volatile vapors, an engine loading system automatically operated by the controller(s) applies an automatically adjustable braking load on the engine. The load level applied is based on the sensor data and commensurate with maintaining stable engine running conditions. The loading system decreases time necessary to remediate a site.