QuestionBen. Greetings from the UK. I hope you can help.
I have a Mountfield rotary mower with a Briggs & Stratton engine. Model:10D902, Type: 0129B1, Code: 05022851. It is about 4-5 years old. My problem is this. The engine starts very easily but then runs very roughly - 'hunting' would be an appropriate word. I checked the most obvious (to me) things. Plug was fouled with oily deposit. When cleaned and replaced it gets to be in the same state immediately which to me suggests oil in fuel. Fuel in tank clean. Checked air filter. Clean but cleaned and replaced anyway. Ran engine with air filter off and incoming fuel to carburettor was stained with black oil spits. The carburettor is non-adjustable. How on earth can oil get into the fuel between the tank and carburettor and what can I do about it?
Many thanks in anticipation.
AnswerFred
When was the last time you changed the oil?The reason this happens is to much oil in the engine causing the oil to be forced to come out from the breather system,which includes the air filter and the carburetor. Check the oil and take some out, re clean the plugs ,air filter. The huning and surging.
If your Engine operates erratically, surges, and runs unevenly.
Possible causes:
Fuel line or fuel tank cap vent is clogged.
There is water in the fuel.
Fuel pump is defective.
Governor is not set properly, sticking, or binding.
Carburetor needs adjustment or service.
Loose carburetor/intake pipe resulting in vacuum leak.
Carburetor is dirty.
Air leak in carburetor or intake manifold (e.g., bad O-ring, gasket, primer).
Carburetor needs service.
