The lawn mower has started to misfire and throw out black smoke. I have cleaned the filter, new spark plug but there doesn't appear to have an adjustment screw to adjust the mix?
If it's a briggs engine with the carb on the tank, replace the diaphragm. Easy & cheap.
Phil Saunders, April 2009
The only usual adjustment is for the pilot mixture, which may be a tamperproof screw on the side of the carburettor. However it sounds to be a bit more than this. Is the choke sticking on? If the air filter is a paper one - dont clean, but replace it.
