5 hp B&S rototiller won't start
 

I know the gas is good because I used it the day before it stopped running. I tried squirting engine started down the carb and into the cylinder head. Normally in the past it would try to start. I checked the spark plug for a spark and noticed that it was giving a weak spark. I cleaned the magneto and the place it contact on the flywheel and then reset the gap using a business card. I then check the plug for a spark. The spark was still weak. I'm beginning to wonder if the magneto is bad, or if there is another contact like a ground that needs to be cleaned. A new magneto costs about $50 and so I'm not looking forward to replace it. Any ideas?

Hi,

Although somewhat rare, I've had experiences in the past where a spark plug would fire weakly when removed and grounded to the engine block. When the spark plug was re-installed, the plug would not fire under compression.

If you haven't already done so, replace the spark plug...

Mark P.
Central State Mower, LLC

Can you post the numbers off the cowling?

If it was built before about '82 it may have points. They can get dirty and a bad condenser can cause a weak spark.