My Ferris FW35 walk-behind mower has engine issues

Hello Folks,

I’ve owned my Ferris FW35 for nearly a year now and had no issues until last week – the engine seems to keep fluctuating in power, sometimes running slow and other times almost stalling or knocking. What could be causing this?


Hi Mildred,

Did you switch to a new type of fuel recently, or change the air fuel mixture? If you did either, this could be the cause as it sounds like your fuel mixture is too rich. If this isn’t the cause I suggest inspecting your spark plug and checking whether the oil level is too low as you mentioned it started having problems only after a year – it may be time to change the spark plug or oil (perhaps even both).