STX 38 won't start

[jnovak01]

Does anyone know why a stx 38 would not start?
It CRANKS, is getting good gas.
It is NOT getting any spark. Thinking it was the coil I bought a new one and installed it with a fresh spark plug. Still it will crank but will not even hint at starting. If I take the spark plug out and connect it to the wire from the coil it is obvious there is NO spark.

Can anyone help?

Thanks!

Joe

[Mower_Man42]

Check all safety switches, check to see that PTO switch is off, is seat switch working. Brake pedel is set in park. Blown fuse?

[Mark / Ohio]

Also make sure your getting the 12V through the key switch to the coil or perhaps another relay when in the on and start position.

[Greg]

Does the tractor have points/condensor? Normal?

Not all that familiar with that model, but....

[jnovak01]

I am getting 12 v on the block that sits 120 degrees prior to the coil pick up on the cover for the engine. there are 3 wires there grouped with a quick connector, one black and two white. I am getting 1 volt AC on the two white ones and 12 v on the on black one. I don't know if this is normal as I do not have a wiring schematic for this machine and am not too familiar with operation of magnetos.

How do I check the seat safety switch?
Should it be closed when you sit on the seat?
If so would not a jumper on the two leads of the quick connector bypass the switch?

Joe

[Greg]

Normally they will be closed(short) when you sit. Jumpers will work on it. But...I would think the engine would not crank with a bad switch. Usually they have to be working to allow 12V, through the ignition switch, to the solenoid to turn the engine over. I just replaced the solenoid on my Craftsman and I could hear/feel the relays close when the seat was pushed down, brake/clutch pedal pushed and manual PTO operated. Yours should basically be the same.

Uncle Greg

[Mower_Man42]

If you have a female plug that goes to the seat switch, pull that plug. Get a zip tie and lenght ways put the zip tie around the plug between the two slots there is a little plastic pin, this has to be pushed and held in. After pulling the zip tie tight the tractor should start without anyone sitting on the seat. This is for testing preposes ONLY just to check the seat switch. if the tractor starts then replace the seat switch that installed in the seat pan, should twist out 1/4 or 1/2 turn.

If the switch is bad the motor will turn over but not fire. I had this happen to my Scott S1742 two switches failed. The service manager showed me a box full of bad switches, I had to wait 2 weeks for the second one because they were out of stock. I could still use the tractor with the zip tie, I used the tractor to mow customers lawns. But I think it`s something else because it should start with the parking brake on, If the seat switch was bad it would stall the second you released the parking brake.

If the wiring schematic is the same as a JD 165 with the 12.5 hp Kawa. I have the owners and parts manual, but my scanner is broken, won`t copy anything. My owners manual says to check all electrial connection the trans shift lever may not be in nuetral, or that swich is bad, or out of adjustment.. Neutral start switch faulty or out of adjustment. Manual says see john deere dealer, not much help there.

[jnovak01]

I will try the zip tie approach. I noticed that there is a small spring connecting the two terminals inside the female connector for the seat switch. This must be a fail safe device in that if the connector is pulled it will not allow the seat switch to be bypassed. One would HAVE to want to defeat the switch by sticking something in the terminal.

Does this tractor have a fuse somewhere? I cannot for the life of me find any fuses?

Thanks for the tip!

Joe

[jnovak01]

There is no pin protruding out so the zip tie would not work. I will have to pull the switch to make sure it is operational.

This sounds like it could be the culprit.

thanks I will try this tonight.

Joe

[Mower_Man42]

There is a 20 amp fuse for the electric clutch, that shown on the parts manual for the JD 165. Your STX38 I don`t know, do you have a electric clutch you should have one also, not sure if that would keep it from starting. Try hot wiring the tractor, maybe the ignition switch is bad.

The zip tie is for the plug with the two wires going to the seat switch. this is what goes into the seat switch. That should have a small plastic pin between the two connections

[jnovak01]

I will try the seat switch tonight.
The PTO clutch I can hear engage when the key is in the on position and I pull the knob for the PTO so I know that is working.

How would you hot wire the tractor?

Thanks

[jnovak01]

I tried the seat switch. It is okay.
I am thinking that it must be the ignition switch, but cannot determine how to test to confirm.

How would you hot wire the tractor?

Joe

[Mark / Ohio]

Originally Posted by jnovak01

I tried the seat switch. It is okay.
I am thinking that it must be the ignition switch, but cannot determine how to test to confirm.

How would you hot wire the tractor?

Joe

Are there 3 terminals on the ignition key switch? If so I would guess one terminal 12V source (constant voltage all positions), one terminal 12V only in start, one terminal 12V in start & run. In other words all three terminals should have 12V in the start position.

I looked on JD's parts site but so far I've only found a picture of the wiring harness but no schematic. Need to buy the service manual to get that I expect.

I think that other block on the engine cover is a voltage regulator to control battery charging. The terminals with 1V probably go to the generating coil on the flywheel?

[Mower_Man42]

On testing and hot wiring the tractor try the link click on electrial and battery service chapter 6. Don`t let the name of the manual scare you, all tractors work the same so most of this will apply. This is a very easy manual to understand with the way it is written, the techs that service AYP built equipment use this manual. It will show you how to hook up a remote starter

Link http://www.mytractorforum.com/images..._%20BOOK_1.pdf

[jnovak01]

Thanks, This is uncannilly like the STX. I performed all the checks and it indicates that I have a bad coil because there is no spark, but I just bought a new coil. It can't be bad but there is infinite resistance between the hi tension lead and the lamination stack. I can get another coil and check that prior to purchasing I guess.

Thanks