Dumb I am. After all this, it was just a loose idle adjust screw that
threaded inward with lightening speed when the engine vibrated. I
thought these were supposed to be held in place by a spring, but the
spring was missing. I few smacks with a hammer and now the screw
binds. I knew the screw was loose but never thought it could advance
that fast!!
Apologies to all the folks who worked so hard on this!
Frank







On Tue, 2 Jun 2009 21:28:40 -0500, "Don Young"
wrote:


"frank1492" wrote in message
.. .
Thanks U. I am praying that is not the case *but* no, I cannot control
the engine speed with the throttle. I am not able to access the engine
again until early next week but I am positive I checked this. In
making certain the linkage to the throttle lever was adjusted
correctly I observed the small plate at the top of the throttle shaft
as it went through its full rotation. What I *cannot* say for certain
is that the shaft and plate were actually moving but I considered
that to be so unlikely I didn't look further.
Understand that the engine started and ran perfectly throughout
the mowing, and it was only when shutting down that this occurred.
So it was sudden.
Frank




On Tue, 2 Jun 2009 07:08:37 -0700, "Ulysses"
wrote:


"frank1492" wrote in message
...
Engine started fine, ran well, but at end of mowing job, engine would
not cut back to idle. All linkages seemed OK, governor spring OK also.
Nothing sticky. Stopped engine by disconnecting plug. On several
restarts, engine went to high speed, no throttle control at all. Was
concerned about runaway, so always disconnected plug promptly. Tried
adjusting low and high speed jets, had no effect. Did not examine
throttle plate. Choke plate operating normally.
I'd bet this isn't a common problem. Is there an easy way to test
the governor by moving the arm manually? As I say the spring seems
fine. Could there be a huge air leak somewhere? Never seen anything
like this before!
Please advise on where to begin. I do not have the engine here now
but would like to begin diagnosis as soon as I return to my camp.
Thanks very much for help!
Frank

Can you still control the engine speed by using the throttle on the carb
and
not the governor? To me it sounds like the governor gear inside the
engine
is worn out.


Your symptoms point to a throttle plate which has come loose from the
throttle shaft. The engine cannot run at high speed if the intake passage is
blocked closed by the throttle plate. So if rotating the throttle shaft does
nothing, there must not be a plate attached to it or the plate is deformed
so as not to close properly.

Just remove the carburetor and see what is going on with the throttle. Be
very careful not to mess up the springs or linkage.

Don Young