CH23S and vapor lock

Tom S. in Tn.

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CH23S-76524 on a 3235 MTD Cub Cadet that starts and runs perfectly cool, but will stop running after 15 to 20 minutes of run time and will barely restart or run with 1/2 choke. New problem that recently started.
Once cool, restarts and runs perfect again.
History: 315 hour engine that has had both head gaskets and ignition coils replaced as well as the valve cover fuel pump.
Cut the pin off the carb solenoid thinking it may be an intermittent problem. Carburetor cleaned twice with new kit once. Tank removed and cleaned with new in line filter.
With engine hot and running and air filter base removed, it appears to boil gasoline in carburetor and bubble out carb vents.
Problem with fuel perhaps?? Help!
 

Rivets

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Have you removed the shroud and checked to see if the fins are clean and the baffles in place. Also a lean fuel setting will cause the engine to run hotter.
 

Tom S. in Tn.

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The engine is mounted backwards with PTO facing front and has to be removed to pull the drive shaft and fan shroud on this 3000 series MTD Cadet. No simple job.
But yes it was cleaned when we put head gaskets and coils on. (one reason those were both done since the engine was off)
There is no main mixture control. Only idle mixture and speed. Trust me, the carb and main jet are clean.
The one uncontrollable variable is the fuel. This mower is old enough to have been built before the day of EtOh and oxygenated fuels. I was hoping to find someone who has been confronted with this also.

Searching around on this forum, I found another commentary where a responder wrote about the several different fittings and new length of fuel line supplied by Kohler with each new fuel pump, and how important it is to 'properly' route the fuel line to the carburetor. Since a fuel pump failure was the beginning of this odessy, I am in the process of rerouting the fuel line and will report back.
Even though I can not see why the pump would not push fuel that short distance, I can see where the neoprene fuel line is touching cylinder baffling.

Thanx; Tom S.
 

Rivets

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I've been around long enough to know how the engine is mounted and that is why I suggested cleaning. No one wants to take the time to do it properly and then make sure the baffles are installed right. You are looking for help with a valor lock or an overheating problem. As I have seen this before, I gave you possible causes, but you seem to know more than me, so I'll leave this thread and let some one smarter than me help you.
 
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