# STX38 no spark



## Rob- (Jun 28, 2012)

Have an STX38 / Hydrostat / Kohler 12 Was running fine. On last start attempt, engine produced one very small backfire on initial crank. Would not start. Changed plug. No spark on new plug. Checked ignition module. Approx 12,000 ohms. In tolerance according to Kohler Engine manual. Disconnect kill wire. - No start. Have not checked seat/ brake / PTO safety circuits however, with key in on position and seat occupied, PTO clutch engages. Have not checked brake switch however, engine will not crank unless brake is depressed. Do not think there is a neutral safety on a hydrostat ( depressing brake forces direction lever to neutral ) I do not have an STX 38 manual. Have looked at a wiring diagram on-line and read some other STX no-start threads and do not know how to proceed from here. 

Would really appreciate some help. 

Thanks,

Rob


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## Rob- (Jun 28, 2012)

Someone told me that disconnecting the Kill Wire from the magneto eliminates all the safety switches and if the magneto still does not produce a spark to start the engine, then the magneto is bad regardless of the fact that it tested in tolerance with an ohmmeter. Can anyone confirm that before I order a new magneto ? - Thanks - Rob


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## tonyennis (Jun 10, 2012)

Rob - I have the wreck of an STX-38 (yellow deck.) It's been sitting a while but probably has some good parts. I'm pretty sure the 'transmission' is out of it; the last time I used it it just stopped moving. I seem to recall a pulley above the back axle just flopping around. 

If you're anywhere near Louisville, KY, you're welcome to it.


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## Rob- (Jun 28, 2012)

Tony - Thanks much for the offer. I'm a bit north of Louisville. ( Connecticut ) but, thanks for the offer : - ) I don't mind just ordering a new magneto. - I am just trying to be sure that is the problem. The Kohler Engine manual states that the resistance across the coil should be between about 7,000 and 12,000 Ohms and, it is within that but produces no spark even when disconnected from the " kill wire " . A tractor repair guy told me that disconnecting the kill wire eliminates everything else,and since the magneto " generates " it's own voltage, it should produce a spark - - if it is good when the kill wire is disconnected. He also told me that even though the Ohmeter test was positive, the magneto still could be bad. - I was just looking to see if someone could confirm that. - Any thoughts ?


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## dangeroustoys56 (Jul 26, 2010)

I had a curious issue a while back with one of my old tractors - wouldnt start ( always started)- cranked over- did not fire.

So did the regular routine of troubleshooting - had spark and gas , so i cleaned the carb- nothing. Checked the spark (nice bright blue) - still nothing. Changed the plug- nothing - unhooked the motor wiring from the tractor - nothing. Gapped/cleaned the mag ends/flywheel - nothing.

So frustrated , i pulled the mag off, swapped one on out of my parts bin - tractor fired right up. Still starts right up - must be mag wasnt putting out enough juice to start it ( spark, but weak spark).

Weirder things have happened....


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## Rob- (Jun 28, 2012)

Thanks for the thoughts ( danergoustoys56) . I installed a new magneto and it fired right up. - Rob


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