Have you changed the air filter?
Mike

Hi Mike,

I did clean the (foam) air filter because it was dirty and drained with oil. Without result. Even with de air filer out the machine runs unstable.

Thanks and regards,
Ed

Try running it w/o the air filter. If the problem persists then you have a rich mixture caused by the choke,if it has one, or the carb has a fuel mixture problem. How does it run at low idle?
Mike

Hi Mike,

I'll try this weekend and keep you posted.

Thanks,
Ed

If you can post the Briggs Model, Type and Code, that would help. Interesting that it runs well when almost out of gas.

I tried running without the airfilter. No positive results. The machine still runs slow and unstable.

Its a B&S XC35 (classic)

Thanks in advance,
Ed

***"Its a B&S XC35 (classic)"***
Well, that is just precious.
But that stuff is just marketing hype.
Look the engine over closely and you will find the "real deal" in identification numbers, most likely will be numbers pin prick etched onto a riveted metal ID plate.
The numbers will be called MODEL NUMBER, TYPE NUMBER, and CODE.
Those are the only numbers that mean anything to a mechanic or parts person.

I think I found the numbers:

9D902 2096 B1 05102751

See attached photo.
Thanks and regards,
Ed

Having looked at the Briggs parts manual (IPL) for this engine, I suspect that the carb mounting diaphragm/gasket (where the carb mounts to the fuel tank) may have a defect in it which is feeding extra fuel through the main jet by engine vacuum instead of simply pumping the fuel in pulses.
The fact that the engine seems to "run better" just before running the tank empty supports the notion that the carb is feeding extra fuel to the engine.
If a new carb mounting diaphragm does not solve the problem, replace the carburetor assembly.

Hi,

Thanks for the quick response. I'll try to find the parts you mentioned here in the Netherlands.

P.S. do you have a link to the parts manual you refer to ?

Try this. Then select Illustrated Parts List (IPL).
http://www.briggsandstratton.com/us/en/support/manuals/results?NTT=09D902-2096-B1

Hi 'Mownie'

I found the diaphragm and gasket and replaced them this evening , together with the spark.
The machine runs great !

Thanks and regards,
Ed

Glad to hear a good report.

Hi

I have an Briggs & Stratton xc35. It starts and runs well but when I stop it after abotu 40 mins running it will not start again. If I leave it for 20-30 minutes to cool down it starts fine. Any ideas what the problem might be?

AW

one thing to check - see if your fuel tank cap vent is blocked.

Perhaps time for a valve adjustment.

Checked the fuel tank cap seems OK.

Can you explain more about the valve adjustment please?