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my 5 HP CRAFTSMAN edger engine dies on full throttle for some reason, this has been a problem ever since I got the engine 1 year ago. maybe it has something to do with the leak in the muffler? I have tried adjusting it and it still has the same problem, but ONLY on full throttle. I have no idea what may be causing this issue. Thanks for any help provided.

Lanerdude9

Give us all number off the engine so we have an idea of what you are talking about. We hate guessing.

ok, haha

i couldnt seem to find one but this is the exact same engine:

ok, so after 30 minutes of long, hard searching the engine, I finally found the dust and dirt-caked engine serial code and model number for the edger! engine serial code: 100202 0015-01 6811127 craftsman edger model number: 536-83610

change the air filter maybe

On that carb there should be a fuel mixture screw on the right side of the carb, under the air filter. Try adjusting this screw 1/4 turn out, counterclockwise, and see if it makes a difference. Sounds like it’s not getting enough fuel at high speed.

Being a 1968 model it very possible that the fuel pickups are clogging with rust from the tank. Also the valve train is probably heavily worn.

I agree, but this is the first thing I’ll bet each of us would try. As we all know with an engine 53 years old not one of us is going to spend a lot of time tearing into the engine. At least I wouldn’t, even though I love bringing back the old mules. Would only tear into it if it were my unit and I didn’t worry about the labor costs. Good winter project for me.

I've seen dirty or wet air filters cause that too.

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.

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 .

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.

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.