Diagnosing Gasoline Contamination in Sawmill Engine Oil

What happens here

Upon restarting the sawmill, the engine immediately begins emitting dense white smoke again, indicating a severe issue. The operator checks the engine's oil dipstick and notices the oil level is excessively high, well above the 'full' mark. He also smells gasoline on the dipstick. This suggests that fuel is mixing with the engine oil, potentially due to a faulty fuel injector or a stuck float in a carbureted system (though this engine is fuel-injected). Recognizing the potential for severe engine damage, the operator decides to immediately drain the contaminated oil and replace it. He uses a 19mm wrench to open the drain plug, allowing the oil-gasoline mixture to flow into a gallon jug.

Goal: Identify the cause of excessive smoke and oil overfill.