Small Engines (Lawn Mowers, etc.): Lawn Boy throttle surges, fuel tank cap, vacuum leak

Question
Hi Ben,
I have Lawn Boy 6.5 HP MODEL #10324, SERIAL #210004053 and recently replaced the ignition module that was bad.  Must of created another problem,because the only way to keep the mower from surging is near full choke.  It won't run smoothly no matter how I throttle it at normal speeds.  I did adjust the throttle after my repair, but can't seem to find the sweet spot for proper adjustment.
Thanks,
Dennis

Answer
Dennis

If the Engine operates erratically, surges, and runs unevenly.
Possible causes:

  1. Fuel line or fuel tank cap vent is clogged.
  2. There is water in the fuel.
  3. Fuel pump is defective.
  4. Governor is not set properly, sticking, or binding.
  5. Carburetor needs adjustment or service.
  6. Loose carburetor/intake pipe resulting in vacuum leak.