My 318 burns very rich, need your advice.

Have you pulled a plug to see what it looks like. If you have run it 2000 miles it cant be to rich it would have fouled the plugs long ago. And with the cheap gas we get now we dont get that light gray in the tips anymore. If your plugs are black then you have a problem. I had to take mine to a guy here in town that knows carbs. He had to drill small holes in my throtle blades to create a small leak so mine wouldn't run rich. I think what you see comming out the back is just water that is a byproduct of burning fuel. Tom