The engine is an Intek 17 hp in Troybilt tractor, about 10 years old. It blew out a lot of white smoke so I shut it down. I dug into it today. Symptoms include: fuel drained out of the cylinder when the plug was pulled, oil was very thin-full of fuel. Every since I got it it would backfire on shut off. I've also had a problem starting this thing for years, it would begin to crank then stop. Thought this was a low battery. But, a month ago I dug into this and pulled the plug and about 8 oz of fuel drained out. I checked the carb. The shutoff solenoid seems work work fine. But, still fuel is running into the cylinder and into the crankcase while it is off. Looking at other posts here, they suggest a needle value problem. Is that right? If the fuel shut off is working how can fuel keep flowing into the cylinder after it is off.