How can I diagnose a power loss problem with a lawn mower?

Question

My lawn mower runs, but seems to be weak and suffering from a loss of power. In general, it is acting as though it is not getting enough air. I replaced the air filter, but the problem remains the same.

Unfortunately, there are about 5 or 6 things that can cause a loss of power and I am not enthusiastic about just randomly trying to fix things that aren't broken in the hopes that the problem will be randomly solved.

Is there any way I can do a test that will positively tell me why I have a loss of power without having to try random maybe-this-will-work type fixes?

Note that I am experienced taking apart carburetors, so if your answer involves instrumenting the carburetor in some way, I can do that.

Note that the mower is a Honda GCV160 which has an "auto choke" system. I suspect that may be the problem.

Answer 1

I believe you do have a carburation problem. I have several Stihl 2 stroke tools and every time I have a "hard to start" or "loss of power", etc. it's been the carb. Fortunately they are only about $30 for a replacement. Every time the replacement carb fixed the problem. Not knowing the specific make/model of your lawnmower if a replacement is as simple as my 2 stroke Stihl units. In your case, if you are familiar with carbs, I'd try disassembling it, clean it and put it back together and try. There are often rubber parts that break, get torn, or get stiff and need to be replaced. If practical, I'd try a new carb, depending upon how old the mower is.