Old Suffolk Punch mower keeps stalling?
 
                I have a (very) old Suffolk Punch, with the engine that uses a Zenith carburettor.  It was running very well.  Then, suddenly, it stalled on me and wouldn't restart.
I cleaned & regapped the spark plug, checked the carburettor float, etc.  It would start and run for a few seconds (but at low power, however much throttle I used), then stop.
Today, I fitted a new spark plug, new float & new float chamber gasket.  I checked the ignition points.
The beast started beautifully and ran at full power for a minute or so.  I stopped it, because I wanted to adjust the clutch take-up.  When I restarted it, it was running at low power for about 30 seconds, then stalled (ie, back to square one).  I suspect the carburettor may be flooding, but not sure.
Any ideas?
            
             John W
            
 July 2009