Small Engines (Lawn Mowers, etc.): John Deere X320 wont start, kawasaki engine, dead mice

Question
I have a JD X320 mower (Kawasaki engine).  When trying to start it, starter turns, but engine won't fire.  Put in new plugs, new gas, changed oil, still won't fire.  Checked for spark --> no spark.  Removed grounding wire from coils and it started right up.  I ran it for about 10 minutes to warm the engine, then shut it off.  Now it will start only when I spray starting fluid on the air filter, and strangely, it now behaves the same whether I connect the grounding wire to the coil or not.  (Some more information: when I opened the engine compartment I found a nest of dead mice up against the engine block, but I didn't find any chewed/bare wires).
Do I have a faulty electrical system, or is something grounding it out?  And why does it now fire when the grounding wire is replaced?
Thanks,
Rick
Pittsfield, MA

Answer
I suspect a fault in the electrical system.  Look at the bottom of the carburetor and let me know if there are one or two wires connected to the bottom of the carburetor.

I suspect you have a bad ground connection.  Did you dis-connect the battery cables and clean the terminal posts and and cable ends with a wirebrush.  This can help solve many problems.

Eric