Why does a Briggs and Stratton 4.5 HP lawn mower engine surge?
I had this problem all last season and thought it was water in the fuel/carb. This year I took it to task. I first insured the vent hole(s) in the gas cap were open. I then ran the mower dry. I got some carb/choke cleaner spray and sprayed it down the throat with a generous amount of solvent. Don’t get too carried away here though. I let it soak for about 15 min. I then blew it out with some computer compressed air, refueled, primed and, after a few pulls…success! I also cleaned the air cleaner with soap and water, dried and oiled according to manufacturer’s directions. The mower now runs just fine. Saved myself a $200 dollar bill for sure. Be sure to wear safety glasses when spraying and blowing out the carb.
