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Discussion Starter · #1 ·
My STX38, a stalwart soul, will just die and not restart after a half hour or less of mowing. The engine cranks but acts like it's flooded. I don't smell excess gas, though.

It is sudden. No outward signs like slowing down, heavy grass, etc. I'm just mowing without a care in the world and suddenly it dies. It's happened on uphills, hard turns, and straightaways.

I'll go back an hour or two later and it starts right up like nothing happened.

I have it maintained once a year (my mowing season is four months). Your thoughts are appreciated.

Perhaps related is that when I stop cranking the engine by turning the key to off it doesn't stop cranking. Even when I pull the key out. I have to shift into a gear to get it to stop. But just shift, not actually put it in gear. This just started, too.

:thanku:

Terry
terry1121
 

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:Welcome1:

sounds like maybe the ignition switch is bad. the sudden shut off could also be a plugged vent in teh gas cap, but i lean more towards the switch with teh other problem.

BTW, you say it continues cranking. do you mean the engine continues running or the starter keeps turning?
 

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Discussion Starter · #4 ·
Actually, if it doesn't keep turning the engine over is makes a nasty weird sound like it's trying to engage the starter but can't.

I'm more interested, at this point, about the engine stalling. I can replace the ignition switch, no problem.

I check the gas cap and it's fine. Thanks for your help!

Terry
 

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ok, if the starter keeps turnign either th esolenoid is bad or the ignition siwtch is bad and tellign it to turn. since you have 2 problesm that can BOTH be directly caused by the ignition switch, i would start troubleshooting there. do you have a VOM to check the terminals?
 

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The stalling problem sounds exactly like a bad coil. When the coil gets weak, it can't bridge the gap when the engine gets hot. It will get worse and worse until it won't even start a cold engine. JD sells the coil for about $70. R&R is fairly simple, done with normal homeowner tools plus a feeler gauge and took this fumble fingers mechanic about 1.5hrs if I remember correctly.
 

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i would tend to agree with that IF he did not also have the issue of the starter continuing to operate when he removes the key. this tells me tha this ignition switch has gone bad internally. it could be causing the machine to "think" he just switched the key off when cutting.
 

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Discussion Starter · #8 ·
Deerdude's thoughts sound logical. It won't restart until I leave it for a while (allowing time for the engine to cool down enough to restart).

Is there a way to test the coil? Also, do you think I need a repair manual to handle this?

I can easily replace the ignition switch. That's on my list anyway.

Thanks for your help guys!! :trink40:

Terry
 

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Deerdude's thoughts sound logical. It won't restart until I leave it for a while (allowing time for the engine to cool down enough to restart).

Is there a way to test the coil? Also, do you think I need a repair manual to handle this?

I can easily replace the ignition switch. That's on my list anyway.

Thanks for your help guys!! :trink40:

Terry
You don't need the manual, but you'll need to know the gap. I think the R&R and gap instructions come with the new coil, but my memory could be off.
If memory serves me, you remove the hood, remove the blower housing cage above the engine and that exposes the coil. Use a couple sockets to pull the old coil and coil wire, then install the new coil. I'd use three feeler gauges and four hands, as you have to get the gap right at both ends and at the center on the new coil. Then put it back together and you're good to go.

I *think* I remember running on issues after shutting the ignition switch with the old coil. But it may be unrelated. Sucks getting old. I suffer from CRS disease (Can 't Remember S---). :00000061:

PS -- JD calls the coil something else, but the parts counter dude should know what you're talking about.
 

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From the JD shop manual for the STX30, 38, 46

Engine runs on after shutdown:
- Inspect ignition switch and ground.
- Inspect engine ground cable
- Adjust idle speed to specs. Move throttle to idle before shutdown.
- Inspect piston, valves, cylinder head & exhaust for high carbon build-up.


Engine won’t shut off:
- Inspect ignition switch and ground.
- Inspect engine ground cable


Engine stops when hot:
- Vapor lock. Check temperature of fuel system. Clear vent in top of fuel cap.


Engine cranks but will not start or starts hard:
- Spark plug fouled or incorrect gap. Incorrect spark plug.
- Defective ignition components.
- Starter worn. Cranking rpm too slow, cables corroded, battery weak. Engine overloaded.
- Fuel tank outlet restricted, shut-off valve not fully open, fuel filter or line restricted. Fuel stale, contains water, or wrong type.
- Air filter element plugged or oil soaked.
- Choke, throttle, or governor linkage worn or out of adjusted. Carburetor set too rich.
- Engine oil viscosity or level incorrect. Engine oil filter restricted. Oil pump worn or passages obstructed.
- Engine gaskets or seals leaking.
- Crankcase breather restricted, reed valve damaged, clearance incorrect, or drain hole plugged.
- Valve guides or seals worn or leaking. Valve stems worn.
- Worn, stuck, or broken piston rings. Cylinder bore worn. Check compression and vacuum.
- Connecting rod or crankshaft bearings worn. Internal wear limits
out of specification.
- Carburetor worn, contaminated with debris or varnish. Passages plugged.
Wrong jets or adjusted too lean.
- Carburetor, intake manifold, or cylinder head gaskets leaking.
- Low compression: worn piston, rings, cylinder, valves. Warped head.
- Valve clearance incorrect. Burned or warped valves and seats. Defective springs.


Engine stalls frequently:
Same list as "engine cranks but will not start..."
except does not include "Engine oil viscosity or level incorrect."

For whatever that's worth....

I still say it's the coil.
 

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Hey Terry,

I would fix the "cranking with the key off" problem before working on anything else. Might fix both symptoms...plus you don't need the starter getting damaged from being in the wrong place at the wrong time! :sad_02:

Gerald
 

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Ignition Module = Coil

From the manual:

[See Pic 1]

REMOVE AND INSTALL STATOR AND IGNITION MODULE
1. Turn flywheel magnet (B) away from ignition module (A).
2. Disconnect wire (D) from terminal.
3. Remove cap screws (C) and ignition module.
4. Remove flywheel (see Remove and Install Flywheel in Engine Repair group).
5. Remove two white stator wires from connector (F).
6. Remove clamps (G).
7. Remove cap screws and stator (E).
8. Inspect for damage.
9. Thread stator wires through hole in crankcase and install in connector. Fasten clamps.
10. Install stator. Tighten cap screws to specification.
11. Install flywheel and tighten cap screw to specification (see Remove and Install Flywheel in Engine Repair section).
12. Rotate magnet away from module mount. Install module loosely.

[See Pic 2]

13. Align flywheel magnet (B) with mounting posts for ignition module.
14. Place 0.25 mm (0.01 in.) feeler gauge blade (K) or shim stock across magnet face.

IMPORTANT: BE SURE flywheel magnet (B) is centered on ignition module (A) so all three polls of the ignition module are properly gapped from the flywheel magnet.

15. Position ignition module (A) so all three polls mate with feeler gauge blade (K) and its two mounting holes align with mounting posts.

16. Install and tighten cap screws to specification.
17. Remove feeler gauge and connect wire (D) to terminal.

Specifications:
Ignition Module Air Gap . . . . . . . . 0.25mm (0.01 in.)
Ignition Module Cap Screws
. . . . . . . . . . . . . . . . . . . . . 4.0—6.2 N•m (35–55 lb-in.)
Stator Cap Screws . . . . . . . . . . . . . . 4 N•m (35 lb-in.)
Flywheel Cap Screw . . . . . . . . . . . . 68 N•m (50 lb-ft)
 

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· Chetallica
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5 Posts
I think I found my answer on this thread.

My STX38 is just dieng (spl?) also. Getting worse, and now I cannot keep it running for more than a few minutes. Thought it was one of the safety switches. but pulled all those, ran them through with a meter and looks like they are all ok. Did the same with the ignition switch also (bypassed with jumpers, ran continuity tests)..looks good. Was hoping it was not a broken wire, but looks good there too.

I'm leaning towards the module/coil since the other posts here seemed to have the same problem and that seemes like the fix.

Lets' give it a shot!

Otherwise, my STX has been agreat machine, the Kohler is the best small motor built imo...runs awesome.
 

· Chetallica
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Follow up....installed the new coil/module on Monday (was $58.00 and was an oem Kohler part) and the old girl fired right up. I let her run for about 20 mins with the blades rolling and no probs. I am doing a full cut today, so I will get my real test in for sure. I'm feeling really confident that the problem is fixed.

Thanks to Deeredude for posting the instructions from the manul, that was a huge help indeed!
 
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