I have further analyzed my engine's performance and have more
information. Actually, after running the engine for an extended
period of time, the following happens:

If I let it sit for about 5-10 minutes and try to start it with the
throttle about 1/2 way and choke out all the way, it will start.
However, it only runs a 2-3 seconds and stops. I have tried all
choke and throttle positions and this seems to be the only thing that
will start. However, as said above, it stops. I have tried leaving
the choke out and pushing it back in quickly.

I have checked the fuel lines and they seem to be ok. The fuel lines
run close to the engine. I did not know that aluminum foil would keep
heat away from the line. I thought it was a heat conducter.


On Fri, 5 May 2006 21:53:31 -0400, "Alan Sung" wrote:

wrote in message
. ..
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.

You have something called "vapor lock" which happens when the area in and
around the carburetor gets too hot. Basically instead of a liquid gasoline
in the fuel line or at the point in the carb where it must flow through the
needle valve, it has vaporized. Yes the gasoline has to vaporize prior to
combustion but this is after the needle valve prior to the intake valve.

First, try keeping the fuel lines away from the cylinder or wrap aluminum
foil around it in an attempt to shield it. Next, check that you have proper
fuel flow from the gas tank thru the lines. Sometimes it "drips" out of the
fuel tank into the fuel line rather than a solid flow which causes air
pockets where vaporization can occur. This can happen by having a piece of
grass or leaf falls into your tank while refueling and it lodges right where
the fuel line connects to the tank. A clogged fuel line or fuel filter could
also restrict flow. Have you ever changed the fuel filter in the 10 yrs? You
might also consider changing the fuel line to one of the clear ones rather
than the black rubber ones so you can see the fuel flow.

Letting it sit for a few hours until it cools gets rid of the vaporization
and it also allows a sufficient amount of fuel to work its way past any
clogs.

-al sung
Rapid Realm Technology, Inc.
Hopkinton, MA