310-8 - No spark/intermittent spark sanity check

[echris 1,425]

Hey fellas, my '89 310-8 cut out while mowing today. It was barely warmed up, but lost spark. While troubleshooting, I found very intermittent spark. I cleaned all the contacts of every connector, verified all safety's were operating but no luck. 
I then disconnected the 5 pin connector going to the engine and jumped the starter, it cranked but still no spark. I swapped plugs and verified the coil gap as well.

I believe we've got a dead ignition coil. And even though it reads about 9,700 ohms, I think the electronic ignition portion is dead.

I don't see what else it could possibly be. 

Also, anyone have a lead on a good coil for this machine. It seems like Kohler doesn't make them anymore. 
EDIT: I found the part number 4758403S but they're pricey! I'd like to confirm before ordering.

I'll file this under, "No good deed goes unpunished." I gave her a full service yesterday and she died on my today. 

EDIT2: Sorry, I should have posted this under WH Electrical.

Edited October 3, 2021 by echris

[johnnymag3 2,520]

Hey.....did you do something when you serviced it to make this happen???? Have you checked the key switch????

 

john

[echris 1,425]

Thanks for your reply Johnny, but unless I'm mistaken, on the 300+ series with a Magnum, disconnecting the 5 wire harness from the engine removes the chassis from the equation. So jumping the starter with 12 volts should give spark.
Am I wrong about this? 

Plz send halp! 

EDIT: I wasted about an hour troubleshooting in the backyard today because I thought it was something I did while servicing it yesterday.

Edited October 4, 2021 by echris

[johnnymag3 2,520]

Jumping the Solenoid should turn the Starter / engine.....not too sure about the power to the Spark plug.....Someone will be along with more input. Did you look at the Wiring diagram? There is one here on Red Square..Good Luck....

 

 

I have a complete 310-8 that I will be parting out soon, its complete, runs perfect.....37 inch deck, wheel weights,,,,and I will be selling the magnum engine also. Let me know if you need anything for your Tractor...

John

[echris 1,425]

Unless I'm mistaken, the Magnums do not need battery or the tractor chassis at all to start (as long as the 5 pin chassis to engine is disconnected). If you have fuel and 12v on the starter, it should handle the rest itself.
The magnets on the flywheel create voltage to the spark plug via the ignition coil. So technically, all you need is a rotating flywheel, a working coil and flywheel magnets.
I think!?!

[johnnymag3 2,520]

If that is the case....you should have spark ???   Hard to tell from here not being right next to the Tractor.....Diagnosing things...

 

John

[echris 1,425]

1 minute ago, johnnymag3 said:

If that is the case....you should have spark ???   Hard to tell from here not being right next to the Tractor.....Diagnosing things...

 

John

You're only like 20 minutes away. S'all I'm sayin' 

[johnnymag3 2,520]

Is the Chinese Buffet open in the Plaza @ Myers Corners Road?

 

 I may have to come visit you....

 

[echris 1,425]

I, umm, don't think there is such a place. Like near Myers Corners and All Angels?

 

Edited October 4, 2021 by echris

[ebinmaine 67,673]

@953 nut or @pfrederi any thoughts on this issue?

 

[kpinnc 12,111]

Check the plug on the backside of the oil pan facing the center console. Should look like a 3/4 plug with two wires going in it. My 310-8 had a low oil float switch that went bad, and that was it. All it does is ground the magneto just like the interlocks do.

 

Speaking of which- check the PTO interlock switches. One is tied to the clutch for starting, the other in series with the seat switch. 

[echris 1,425]

2 minutes ago, kpinnc said:

Check the plug on the backside of the oil pan facing the center console. Should look like a 3/4 plug with two wires going in it. My 310-8 had a low oil float switch that went bad, and that was it. All it does is ground the magneto just like the interlocks do.

 

Speaking of which- check the PTO interlock switches. One is tied to the clutch for starting, the other in series with the seat switch. 

Hey KP, thanks for your reply. I'm pretty sure I eliminated all those possibilities by disconnecting the 5-pin harness from the chassis to the engine and just jumping the start with a 12v supply. I'd be happy to learn that I'm wrong though. 

[kpinnc 12,111]

I'm sure you'll figure it out!

 

Magnums are easy. You just gotta find whatever is grounding them out. As was said earlier, if they spin over and have fuel, they run.

 

...unless it's the mag or plug wire.

Edited October 4, 2021 by kpinnc

[Bill D 1,926]

Pull the flywheel cover off and remove the white kill wire from the magneto, then crank the engine over and see if you have spark.  Also check to see if the plug wire got pinched or cut where it runs thru the engine tins.  If the plug wire is damaged it can be replaced without replacing the whole magneto, I know, I've done it and so have others.  Let me know how you make out. 

[Gregor 4,846]

If I am reading these diagrams correctly. the low oil switch can prevent voltage from going to the starter, but does not effect the ignition.

These diagrams also show a "test" switch.??????

 

[953 nut 55,325]

Most 310 models don't have a low oil switch.

11 hours ago, echris said:

Unless I'm mistaken, the Magnums do not need battery or the tractor chassis at all to start (as long as the 5 pin chassis to engine is disconnected). If you have fuel and 12v on the starter, it should handle the rest itself.
The magnets on the flywheel create voltage to the spark plug via the ignition coil. So technically, all you need is a rotating flywheel, a working coil and flywheel magnets.
I think!?!

That is correct. however there is a piece of wire from the magneto coil to the 5 pin connector that could have a potential for shorting out the mag.

4 hours ago, Bill D said:

Pull the flywheel cover off and remove the white kill wire from the magneto, then crank the engine over and see if you have spark.  Also check to see if the plug wire got pinched or cut where it runs thru the engine tins.  If the plug wire is damaged it can be replaced without replacing the whole magneto, I know, I've done it and so have others.  Let me know how you make out. 

              do what @Bill D suggested.

[kpinnc 12,111]

4 hours ago, Gregor said:

These diagrams also show a "test" switch.??????

 

The mid to late 80s machines had a row of LEDs on the dash for different notifications. The test switch just turned them all on at once so the owner knew they all worked.

[gwest_ca-(File Mod) 11,050]

If I remember correctly the 10hp models only have a low oil light in the starter circuit.

[echris 1,425]

Thanks guys.

Yes, the '89 310 has a low oil sensor with a single test lamp/switch on the dash.

I've removed everything from the equation including the white kill wire, just in case it was shorted somewhere during the path. I did a continuity test on the kill wire and it wasn't grounded.

I'm going to double check the plug wire. I did remove the clamp when I removed the muffler the other day. Good thinking!

I don't think there's anything else it could be, I doubt the stator goes bad very often on these, so it's likely the coil. Correct?

[Snoopy11 5,714]

1 hour ago, echris said:

Thanks guys.

Yes, the '89 310 has a low oil sensor with a single test lamp/switch on the dash.

I've removed everything from the equation including the white kill wire, just in case it was shorted somewhere during the path. I did a continuity test on the kill wire and it wasn't grounded.

I'm going to double check the plug wire. I did remove the clamp when I removed the muffler the other day. Good thinking!

I don't think there's anything else it could be, I doubt the stator goes bad very often on these, so it's likely the coil. Correct?

This may be a more... obvious question... but did you recheck the spark plug gap... and actual spark plug? Maybe you have a bad plug. I had a similar issue on an engine, actually turned out to be the spark plug of all things. Evidently, I just bought a bad one. 

 

i.e... you just don't want the spark plug to be the boogger that is grounding you out...

 

Wasn't it @squonk that says "let an electrician check your shorts..."???

 

Don

Edited October 4, 2021 by Snoopy11

[echris 1,425]

Yeah, I checked and replaced the plug.  That was one of the first things I did. Remember, check the gas before replacing the engine! ha!

[Snoopy11 5,714]

1 hour ago, echris said:

Yeah, I checked and replaced the plug.  That was one of the first things I did. Remember, check the gas before replacing the engine! ha!

Is there a tremendous amount of rust on the flywheel... or magneto coil?

 

If so... you might want to check out the following:

 

 

 

Don

Edited October 4, 2021 by Snoopy11

[Bill D 1,926]

3 hours ago, echris said:

Thanks guys.

Yes, the '89 310 has a low oil sensor with a single test lamp/switch on the dash.

I've removed everything from the equation including the white kill wire, just in case it was shorted somewhere during the path. I did a continuity test on the kill wire and it wasn't grounded.

I'm going to double check the plug wire. I did remove the clamp when I removed the muffler the other day. Good thinking!

I don't think there's anything else it could be, I doubt the stator goes bad very often on these, so it's likely the coil. Correct?

Don't forget that the plug wire coming off the coil is 30 years old.  It could be leaking, especially where it's clamped to the engine or runs thru the tin work.  The stator is for battery charging and headlights and has nothing to do with spark.

[Gregor 4,846]

21 hours ago, echris said:

I then disconnected the 5 pin connector going to the engine and jumped the starter, it cranked but still no spark. I swapped plugs and verified the coil gap as well.

You disconnected the wires coming from the motor, and jumped the starter, and where does the blue wire from the magneto go now?  I believe the white wire comes from the stator. As said above, the stator has nothing to do with ignition. If there is a short to gnd in the blue wire, I think you have a problem.

 

Edited October 4, 2021 by Gregor

[Gregor 4,846]

22 hours ago, echris said:

I found the part number 4758403S but they're pricey! I'd like to confirm before ordering.

That looks to be correct. They are on ebay for less than $20. Buying coils on ebay is kind-of a crap shoot. Might get a good one, might not.

 

From Kohler manual

9700 ohms seems to be within spec

 

The kill wire, (whatever color it is) could be grounded under the flywheel, or some where else on the motor, before it ever reaches that 5 pin plug.

 

 

Edited October 4, 2021 by Gregor