QuestionI have got into the carburetor and sprayed carburetor cleaner into it from all angles. I have not gotten into the area under the hood. I have changed the spark plug. The 4.0 Briggs and Stratton engine runs rough with smoke coming through the muffler - it will run a few seconds and then die. I am wondering what it will take to fix it or if I would be better off spending about 150 tax included to get a new one at Sears with a 4.5 B and S engine - it actually might run 135 or 140 tax included. It would be a mulcher with a rear bag. It does need the combustion areas serviced as they have a lot of hours on them. Thanks!
AnswerHi Don,
You could try adjusting the carb. The high speed mixture screw is initially set at 1&1/2 turns out. Then adjust it to give good acceleration and top speed while keeping the screw as far out as possible. The low speed mixture screw is set at 3/4 turn out, then adjust to give a smooth idle. If no change, then the carb most likely has dirt, debris or gummed fuel inside.
First, check the gas cap to make sure it is venting and not causing a vacuum in the tank. If that's okay, you will need to remove the carb, disassemble it, clean all the small internal openings and blow it out with compressed air. Probe each and every hole with a small wire. A carb rebuild kit wouldn't hurt either.
Let me know how you make out.
Michael
PS If the mower is old, it might not be worth it to repair and you might be better off, replacing with new.
