JD STX38 starting problem

335 Views 14 Replies 6 Participants Last post by JoeIsuzu, 18 d ago

JoeIsuzu

Discussion Starter · 24 d ago

New here! Im having problems with my JD stx38. Got it used last year for 40$ from a guy I served with, and ran pretty dang good, I knew the starter was probably going out as it was weak sometimes and would barely turn the engine over. Welp Ive gotten it back out to mow my back yard and darn thing wont start, almost turned over once then nothing.. no click nothing.
1. I put the battery on a tender and its good
2. replaced the solenoid (old one had a broken stud)
3. replaced the solenoid and jumped it with cables, starter spins and operates properly from what I can tell.
Installed it back on the rig and nothing..
4. replaced the starter relay, Now everything clicks on like it wants to start but no movement form the starter itself.

I can hear the solenoid click but the starter wont move. I did take it apart and clean all the old grass and crud out of it reassembled just fine. Checked all the grounds I could find and nothing seems out of the ordinary, seat switch works, the key switch seems fine. PTO switch clicks too when key is engaged.
So either the starter is bad or im missing something..
I was a C17 crew chief for 13 years and I keep a 1990 isuzu pickup on the road with nearly 400k on it, sometimes these damn little engines are just irritating.

Im going to try and jump the start while its installed on the rig to see if itll engage, If it still doesnt turn over im going to assume the starter is actually toast.

Reactions: 1

1 - 15 of 15 Posts

Brad

· #2 · 24 d ago

So, when you turn the key to "START" you get a click down by the solenoid, correct? If so, don't change any more parts, just read this article:

www.mylawnmowerforum.com

Starter Assist Relay

***Update! Sister Site MTF Member Stripmine drew up some illustrations to help with the CORRECT way to install a Starter Assist Relay. It's with his permission that I have inserted those drawings into this submission. It really shows "how to" and especially "how NOT to". My thanks to him...

www.mylawnmowerforum.com

www.mylawnmowerforum.com

Also, watch this you-tube video:

Should fix you right up. Let me know if you need any more info or have any questions.

JoeIsuzu

Discussion Starter · #3 · 23 d ago

Brad said:
So, when you turn the key to "START" you get a click down by the solenoid, correct? If so, don't change any more parts, just read this article:

Starter Assist Relay

***Update! Sister Site MTF Member Stripmine drew up some illustrations to help with the CORRECT way to install a Starter Assist Relay. It's with his permission that I have inserted those drawings into this submission. It really shows "how to" and especially "how NOT to". My thanks to him...

www.mylawnmowerforum.com

Also, watch this you-tube video:

Should fix you right up. Let me know if you need any more info or have any questions.

I am almost positive im not getting power to the purple wire leading from the relay to the solenoid. Ill check for voltage tomorrow. So the dude in the video did he just add a whole other relay?

laser3kw

· #4 · 22 d ago

You can test the starter while mounted on the egine. Take your jumper cable and attache one end to the battery positive and the touch the other end to the big lug on the starter. If the starter reacts normally, it is a good bet it is not shot. Then, try jumping 12v to the solenoid "S" terminal (small terminal). If that pulls the solenoid in and spins the starter / engine, take a look at the fuse. It is sometimes in the battery compartment and some times under the hood. If the fuse is still good, then there maybe a safety switch not making. Brake switch, blade engagement switch, seat switch.

Reactions: 1

JoeIsuzu

Discussion Starter · #5 · 22 d ago

laser3kw said:
You can test the starter while mounted on the egine. Take your jumper cable and attache one end to the battery positive and the touch the other end to the big lug on the starter. If the starter reacts normally, it is a good bet it is not shot. Then, try jumping 12v to the solenoid "S" terminal (small terminal). If that pulls the solenoid in and spins the starter / engine, take a look at the fuse. It is sometimes in the battery compartment and some times under the hood. If the fuse is still good, then there maybe a safety switch not making. Brake switch, blade engagement switch, seat switch.

The started tested fine in and off the rig, I’ll go through all the switches and see if one is just not getting contact anymore. I did find a fuse under the key switch box, had a old school glass fuse that was blown. I replaced the fuse and my issues continue.

Grunt

· #6 · 22 d ago

Welcome to MLF Joel. Thank you for your service. You could fit four of the little A-4's I worked on inside your C-17.
What motor is on your John Deere? If it is a Briggs & Stratton, the valves may need an adjustment. A typical sign of the valves out of adjustment is the engine will try to start until the cylinder reaches the compression stroke and stops. Turning the engine by hand past the compression stroke will allow the starter to turn the engine UNTIL it again reaches the compression stroke. There are many youtube videos to help you. Let us know what you find.
Here is one-
(143) ( HOW TO ADJUST VALVES) FIX HARD TO START Lawn Tractor with OHV Briggs Engine- MUST SEE- Part 1/2 - YouTube
(143) ( HOW TO ADJUST VALVES) FIX HARD TO START Lawn Tractor with OHV Briggs Engine- MUST SEE- Part 2/2 - YouTube

See less See more

JoeIsuzu

Discussion Starter · #7 · 22 d ago

Grunt said:
Welcome to MLF Joel. Thank you for your service. You could fit four of the little A-4's I worked on inside your C-17.
What motor is on your John Deere? If it is a Briggs & Stratton, the valves may need an adjustment. A typical sign of the valves out of adjustment is the engine will try to start until the cylinder reaches the compression stroke and stops. Turning the engine by hand past the compression stroke will allow the starter to turn the engine UNTIL it again reaches the compression stroke. There are many youtube videos to help you. Let us know what you find.
Here is one-
(143) ( HOW TO ADJUST VALVES) FIX HARD TO START Lawn Tractor with OHV Briggs Engine- MUST SEE- Part 1/2 - YouTube
(143) ( HOW TO ADJUST VALVES) FIX HARD TO START Lawn Tractor with OHV Briggs Engine- MUST SEE- Part 2/2 - YouTube

It’s the kholer command 12.5. As it currently sits it won’t even turn over. I just checked the seat switch and it still works. Someone had commented or I read there is a brake switch as well, I’ll be looking for that next.

JoeIsuzu

Discussion Starter · #8 · 22 d ago

where does this need to be plugged into? It was just dangling down near the tire, may just be a dead connector for an accessory I don’t have.

Green Motor vehicle Gas Auto part Machine

See less See more

Dutchy491

· #9 · 22 d ago

How old is the battery? Have you load tested the battery? Will it crank better if you boost it from your truck? Truck not running when you do this!! Good luck 🤞

JoeIsuzu

Discussion Starter · #10 · 22 d ago

Dutchy491 said:
How old is the battery? Have you load tested the battery? Will it crank better if you boost it from your truck? Truck not running when you do this!! Good luck 🤞

Battery is from june of last year, and I keep it on a battery tender in the winter. I dont think the truck will help much at this point. its either some stupid safety switch or I need to wire up another relay.

Dutchy491

· #11 · 21 d ago

My simple suggestions above are free to try, …unlike some of your other attempts 🤷

Freddie521

· #12 · 21 d ago

I'm confused at this time, does the solenoid click when the key is turned? If so, it's not a safety switch. If it does, remove the plug and see if it will turn the engine. If it turns try the valve adjustment as suggested.
If no click from the solenoid, then touch 12v to the small terminal on the solenoid. If it now clicks, then you have a blown fuse, bad key switch, dirty or bad safety or a bad connection.

JoeIsuzu

Discussion Starter · #13 · 21 d ago

Freddie521 said:
I'm confused at this time, does the solenoid click when the key is turned? If so, it's not a safety switch. If it does, remove the plug and see if it will turn the engine. If it turns try the valve adjustment as suggested.
If no click from the solenoid, then touch 12v to the small terminal on the solenoid. If it now clicks, then you have a blown fuse, bad key switch, dirty or bad safety or a bad connection.

I miss spoke earlier, after looking at it further the click I hear is the starter relay clicking as I turn the key from run to start. I Checked continuity on the key switch and its good, seat switch too. I found a fuse where the key switch and PTO engagement switch are. It was blown but after replacing it Im still having the same issue. Is there another inline fuse im missing?

Like the guy in the Youtube video posted above I turn the key to run and check for power at the purple wire, the brake and seat are depressed, still no power at the purple wire; although the starter relay does click. I did use some jumper cables and was able to get the solenoid to function and engage the starter.

I havent been able to find the other safety switches yet im sure someone can chime in with their location?
It looks like someone had wired another relay in next to the battery at some point, it says Hella on it and I dont think John deere would have used a Hella relay? The picture below I still have no idea where that plug is supposed to go if it goes anywhere, and Ive included a picture of the other relay in the battery compartment. If any other STX38 owners have this maybe you can chime in as to its function.
Thank you all for your help so far.

Green Motor vehicle Gas Electronic device Machine

Electrical wiring Cable Gas Automotive fuel system Auto part

See less See more

2

Freddie521

· #14 · 20 d ago

If there is no other wires going up to the seat, this must be for it. For 12v to be at the solenoid start connection, the key must be turned, the blades (PYO) must be off, the brake must be on, the trans in neutral and someone in the seat. There may be other safety switches if there are more attachments. Using you machine model number, you should be able to find a wiring diagram and maybe a harness picture. These are sometimes found in the parts manuals. I would find each, do a visual check first, then unplug them, clean the connections and verify the wire condition. With disconnected, verify the switch operation per the wiring diagram. Reconnect and go to the next.

You could unplug the key switch and put 12v to the purple S connection and see if the solenoid responds. If not reconnect, turn the key and see if 12v shows on the purple. You may have a disconnect between the key sw and the solenoid such as that added relay.

See less See more

JoeIsuzu

Discussion Starter · #15 · 18 d ago

Problem solved. The dangling pigtail was to the transmission must have been pulled off by the deck lifter also I cleaned every terminal, ground, connector that I could find. Not really sure what was the final fix but it fires right up and runs good. Just need to replace the belt that powers the blades and itll be in good working order. Thank you for all your help.

1 - 15 of 15 Posts