[dericdomino]

My 4 yr old self propelled push lawn mower is getting harder to start each week. The first 2 years it started in one pull. Now about 10 pulls. And, as it runs you can hear it rev up and down continually.
I change the oil every year usually twice per season. I use fresh gas in it every week.
Last month I took it to a shop they said it was all tuned up but it functioned exactly the same as before I took it to them. I think they just changed oil and gas only and called it a tuneup, which is what I do anyway.
What does it need? Please help me figure it out. Thanks.

[smearcase]

This video or others similar to it may help:
PushMowerRepair.com - Briggs 3.5HP Adjusting Governor to Change Rpm - YouTube

[parttime]

Hi deric, if it were mine I would pull the carb and clean the reservoir and inspect/replace the diaphragm. Is that something you would be comfortable doing? It so post back. Good luck

[smoothy]

Get a can of SeaFoam at your local autpparts store (the other stuff is worthless except the much more expensive BG44K from BG products)... pour it into a 5 gallon gas can you use to fill the mower and it should clear up the varnish buildup that is occurring. Alternately you can pour a few sloshes into the tank (exact amount isn't critical as it can be assumed its not a two stroke mower if its only 4 years old)

[crigby]

Hi,
I would have to agree with the second two suggestions: firstly, I think you have partially obstruted low-speed circuits; and additives can be beneficial in eliminating varnishing which can be common in today's fuels.
Over forty years ago I learned the functions of the various carb circuits. The low speed circuit functions at idle when the throttle is closed by bypassing the throttle valve at least partially. Operation is with the first 1/4 of throttle. Then is the intermediate circuit(s) which operate through the jet body that is in the venturi and works in the 1/4 to 3/4 throttle range. Finally, there is the main jet which supplies all other circuits and takes over in the 3/4 to full throttle range. All circuits are used at full throttle and a dirty low speed circuit will lead to difficult starting and "hunting" when running. The main jet rarely actually determines much in most lawn equipment since the engines are rarely set to run at rated RPM.
Peace,
Clarke

[dericdomino]

Thanks to all for the advice. Will try the things everyone has suggested.

[parttime]

Hi again deric, Let us know how it goes, may help someone else later.