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Discussion Starter · #1 ·
I have a John Deere Stx38 (160001 - 210000) that will not start. It was running fine and got bogged down with grass and stalled. It now will not start. It turns over and there is spark at the plug. I have done the troubleshooting steps and all the wiring seems fine and safety switches are working. When doing the cranking circuit test (from technical manual) I do not get battery voltage at S2 when in the run position I get just under 6 volts. I get the same voltage on the purple wire of the starter solenoid. I get battery voltage at S1. The manual says to replace the key switch. I just want a verification before replacing the switch. I would have expected a bad switch to have 0 volts.

Thanks in advance.
 

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You say it "turns over"... if you deem it to be about the same cranking speed as before...Then do Not replace any components..[switch]....If it cranks real slow...then yes...
You may have spark and fuel...but sometimes when the engine does an abrupt stop..]bogged down] it can cause the flywheel key to sheer...You may want to unbolt the big bolt [or nut] atop flywheel and look closely at the keyway slots...they may be offset..and need new key...Like they say,"timing is everything'..
 

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Discussion Starter · #3 ·
Thank You Suspicionofignorance for the information. I will check that out but it will probably be a couple of days or possibly until Saturday before I can look into it. I appreciate the quick response.
 

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Discussion Starter · #6 ·
So I ended up taking a look and the alignment looks fine. I can see the key in the key way and it does not look sheared. Without pulling the flywheel off I cannot be certain but I will need a flywheel puller to do that. I left it disassembled in case you recommend pulling the flywheel.
 

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No...you should Not need to remove the flywheel for key inspection...Sounds like it is OK...and your problem is elsewhere...Is that a Kohler or Briggs engine ? Can you hear a faint click sound at the carb bowl solenoid with key on/ key off...Can't really imagine how you woulda lost it anyhow..from a stall out...
 

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Discussion Starter · #8 ·
Suspicionofignorance it is a Kohler Command 12.5. I am hearing a click at the carb bowl solenoid.
 

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To inspect the key you usually need to remove the nut/washer but then you can see if the key-way in the flywheel matches up with the key-way in the crankshaft. They should match perfectly.



Not like this:

 
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Discussion Starter · #10 ·
I did the ignition module test.

Spark plug wire to core - 9,100 ohms
Primary lead to core - 5 ohms both directions.

This tells me that is bad and needs replaced. Can someone confirm my thinking. The technical manual says one direction should be between 5 and 1000. The other direction should be at least 30k
 
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