I have an old (1984) MTD with an 18hp b&s I/C. When changing the air cleaner I noticed it was wet. I ran the engine with the air cleaner off and watched gas spray up in the air from the carb at every rpm except W.O.T. What causes this? Thanks.
With out knowing your model number, I can only assume that it is an opposed twin cylinder. There is a couple of thing that could cause this. The carb is not gravity fed, is uses a fuel pump incorporated in to the carb, so if the inlet needle and/or the float is not working, it will flood when running. The most common problem that we see that causes this is that the valve clearance is not correct. The correct clearance for an opposed twin is: intake .004 – .006, exhaust .007 – .009, cold, with the opposing cylinders valve springs installed. The possibility of valve leakage could also be an issue. A check and repair of these items should solve your problem. Thanks, Joe