On Sat, 25 Apr 2009 20:43:02 -0500, Don Young wrote:

"Michael Dobony" wrote in message
...
My daughter's 4 cycle string trimmer seems to be locked up. You can't
pull
the cord at all. With the spark plug out it pulls okay. My thought is
valves stuck closed. Any other ideas for excessive compression? BTW, its
a
Troy-Bilt.

Mike D.
One or both valves stuck closed will result in NO compression, not increased
compression. The common cause of your symptoms is hydraulic lock, oil and/or
liquid gasoline in the cylinder. It can also be caused by an incorrect (too
long) spark plug fouling the piston top. An excessive carbon build-up can
increase compression but cannot cause lockup which is relieved by removing
the spark plug. Try turning the engine over with a finger over the plug hole
to generate slight compression and this should give you a pretty good idea
what is wrong.

Your engine might be equipped with a starting compression release which is
malfunctioning.

Don Young

Yup, hydraulic lock. His neighbor told him that yesterday. He told me
about it late last night. He took the spark plug out and pulled like
crazy, put the spark plug back in and it is running again.