When the engine stops, you need to immediately check to see if it has any spark. It MAY be that the solid state ignition is going bad. Does choking have any affect on the engine when it starts to die? Is the vent hole in the gas cap open?

Walt Conner

If you are daring, I would also hook up a small tank directly to the carb to eliminate fuel supply problems.

I had one recently that had a pinched fuel line and progressive got worse over a 3 year period where it would run for 30 minutes and then eventually 3 minutes. The pinch was caused by 2 tie straps on the line and the pinch was not visible.

The owner had it to the dealer twice $$$$ and they rebuilt the carb, etc. and never checked the fuel line.

Yes I have blown out the gas cap,and have opened the cap when it starts to run bad and this does not help. When it starts running bad,I can make it run better for a while by choking it. How do I check for spark when engine dies?

Pull out the plug and ground the threaded end with the coil wire hooked up and crank/pull.

If you have to choke it, you are too lean somewhere in the fuel system.

Try the auxiliary tank trick.

Why would it become lean after 20 mins.? Thanks

Good question. But that's exactly what happened over a three year period to this other mower.

I'd check out the points and electrical and go from their B&S are very simple engines.