Briggs & Stratton Carburettor Diaphragm/Gasket Kit. 795083

My cheapo Mountfield lawn mower was starting to run very rough.
It started o.k., but then the engine "hunted" - would not idle properly, with clouds of black smoke periodically and trying to stall when cutting.
Seemed like the governor was at fault!
I pulled the spark plug - it was covered in black soot - running too rich?
The air filter was clean and clear, I ran some carb. cleaner through the throat of the carb whilst running up the engine by pulling the governor spring gently.
Still no improvement.
The governor springs were all clean and moved freely - as did the governor arm by the fan (under the engine shroud).

I was sceptical that a replacemnt diaphragm would cure this - but for the price, it was worth a go.

It is best to remove the fuel tank from the mower first, with the carb. still attached. Just two bolts to undo, a rubber union hose to gently pull off and then tilt the tank to wiggle off the "Z" bend wire arm thingy from the governor - all of the springs etc. do not need to be touched - they stay on the engine.
With the tank/carb. on the bench its easier to work on it.

Empty the tank of any residual fuel carefully (safety) and might as well check its insides for debris/corrosion.

Undo five set screws to remove the carb. body and withdraw it upwards - watch out for a long plastic pipe/filter and a short coil spring sitting on the old diaphragm!
Might as well check the filter/clean it whilst its out of the tank.

The old diaphragm looked intact - but somewhat stretched and floppy.

Peel it off with the old gasket and fit the new diaphragm first - to the tank face, followed by the new paper gasket, then the carb. body - get it in the right order!
Re-assembly is the reverse as before - but do up the set screws evenly to avoid harming the gasket/diaphragm.

After re-assembly and some fresh petrol, the engine started immediately and settled down to its old sound and performance - job done.

I suppose the old diaphragm was worn/stretched a bit and was allowing too much fuel to be pumped up to the carb?
Anyway - for the price of this little kit, a very simple, easy and cost effective repair.
Well worth doing.

Had many problems with my mower, poor starting, 'hunting', black smoke, sooted up plug, press bulb not working correctly.
I did an internet search about these problems and everyone said 'change your diaphragm and gasket'

After checking where to get the parts Amazon came up trumps. The supplier was quick, reasonably priced and efficient.

Stripped the carb (instruction from the internet) cleaned everything out, replaced the Diaphragm/gasket and everything now works perfectly. Starts first pull and sounds like a mower should.

My 3 year old lawn mower started coughing, spluttering and stalling before finally refusing to start. A bit of research with Google suggested it might be the diaphragm so bought this set to try.
Very easy to replace and the mower now runs perfectly ok.
Much cheaper than a new mower.