5 HP CRAFTSMAN edger engine dies on full throttle

[Craftsman Garage]

ok, I cleaned the air filter, re-gapped the sparkplug which is SUPPOSED TO BE 0.030, BUT WAS AT 0.060, and shot a bit of seafoam deep creep into the needle hole, and this thing... ok, I start it right up and immediately notice the difference of tension in the throttle, and at full throttle, this beast sounds insane loud, is a champion at edging, and could be a 40MPH GO-KART engine. Wow, the things seafoam can do... by the way, the real "champion" is the champion sparkplug hahaha.

 

[bertsmobile1]

Not the seafom
It was regapping the plug
At double the gap the spark would be retarded so the engine will not rev and when it does it would have no power .
Also because electricity follows the path of least resistance a lot of the time it will run down the side of the electrode rather than jump the gap .

 

[sgkent]

at full load the cylinder pressure would have been greater and the spark weaker with the wider gap. A slightly richer or leaner mixture might not have ignited. A dirty air filter would have caused the mixture to be richer.

 

[Fish]

One thing to consider on these old engines, is that over years of sitting around, beads of water sit in the bottom of the gas and rust things. Other than the actual rust, right under the carb is a little cup that is supposed to hold a bit of gas, but after time that cup develops rust holes, and that cup won't hold gas.
Another thing to think about, is that the engine has points and condenser, which can give you a wide range of problems. The air filter has also likely broken up, the diaphram in the carb is likely crispy.
I am betting on the rust holes in the tank cup here.