reader wrote:

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I have a 10 year old Poulin Pro that has a Kohler engine. The
symptoms of my problem are simple. After the mower has sat overnight,
it is easy to start. Even if I run it only a short time, it is easy
to start. However, if I run it for an hour or two and shut it down, I
may not be able to start it back up. It appears that the problem
occurs only if the engine has been run an extensive amount of time and
then shut down. In that case, it won't start until I let it sit
overnight. What is going on? Any advice will be appreciated.





My guess is spark. When it is the most likely to not start, stop the
mower, remove the
spark plug, and then check for spark. Don't forget your asbestos gloves.

This seems to be a common question on this NG.

An internal combustion engine needs three things to run:
1) fuel (proper gas/air mixture)
2) spark (ignition at the correct time)
3) compression (the air/fuel mixture must be properly compressed)

So what I do is start with the easiest first. Pull the spark plug cap, crank
the engine and make sure you have spark. Then I put a compression gauge into
the spark plug hole and test the compression. You may need to refer to the
manual or check online to ensure your reading is within specs. The next
thing I check is the fuel system. A trick I use is to remove the air cleaner
and put my hand completely over the intake. Crank the motor and my hand
should be wet with gas. The motor should sputter and want to start (just
like when you choke the motor).

I suspect you have low compression (when the motor is hot) and after it
sits, things cool off, the compression is slightly higher, and it starts.
But this is only a hunch- T/S is required.

I hope this has helped.