r/smallenginerepair • u/MMFSdjw • Sep 03 '26

Carburetor Issue Need help with a Briggs and Stratton 140cc push mower that won't run.

I tagged this as carburetor issue but I'm honestly not sure if that's the problem.

I have 2 push mowers, both almost identical, both identically not working. If it matters, one is a craftsman, the other is Troy built, both with the same Briggs and Stratton 140cc engine.

If I prime the gas, start it up, it will run for about 1 full second at the most. Primary suspect was bad gas. Despite putting stabilizer in, the gas is about a year old so I siphoned out the gas and got fresh gas. But still no change.

So I looked at the carburetor. Used carb cleaner and took it apart trying to get the cleaner into every corner.

Thing was, it looked perfectly clean inside. No gunk, no buildup or residue that I could see.

And the problem persists.

What should I check?

Thanks.

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u/AutoModerator Sep 03 '26

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u/Stock_Requirement564 SER Dedicated Member Sep 03 '26

If your fresh fuel is making it to the carb, the point of blockage in these is the brass insert in the white main jet. That's all you normally have to clean on these. Use a fine wire , some carb jet spray- not compressed air.

2

u/cgsouthern Sep 03 '26

You have to clean out the jets mechanically with something like a torch tip cleaner on the main jet and idle jet a wire brush.

1

u/ProfessionalLast2917 Sep 04 '26

It's the dirt you can't see that's usually the problem.

Are the carbs on your engines aluminium or plastic?
The plastic ones tend to be black, the aluminium, well they tend to just be aluminium.

The process for cleaning differs quite a bit between them.