Is my B&S coil bad?

[Oldwolf]

Couldn't get my Snapper started today. It's 12 years old but has been old faithful.

Anyway, usually it starts on the first pull, Today...nothing.

It looks like it has no spark.

I pulled the coil and took these Ohm readings.

Plug wire to armature: 5000 Ohm
Plug wire to ground tab: 5000 Ohm
Ground tab to armature: 0 Ohm

The ground tab is connected to a shutoff switch which appears to be working OK - 0 ohms when closed and a open circuit when the switch is open.

It seems to me that the ground tab to armature should not be a closed circuit (0 Ohms), but I am not sure about that. I can't find a schematic of the coils and how it is wound.

This is a picture of the coil and what I am calling the ground tab.

Do these readings indicate a bad coil to you?

Thanks for your help!

 

[Oldwolf]

PS-I use synthetic oil in it - 10W-30.

 

[Warstud]

Was your mower giving you any problems prior to it ...not running?

 

[mechjames]

Usually a simple test we do is, disconect the ground wire kill switch, and see if it runs. If it does, use an insulated screwdriver with gloves on and kill it either by touching the spark plug top to the head. Or if its insulated, choke the carb, or turn off the fuel shut off if it has one.

If it runs with the kill switch disconnected, theres something wrong with the kill switch or the wire to it is shorting out. If not, well check your gap between the magnets on the flywheel and the igntion coil. Try again. If not, coil is probably dead.

edit: AND BTW, i use synthetic 10w30 Amsoil 4 stroke formula in my small engines too!

 

[Oldwolf]

Warstud - no problems until today.

mechjames - I didn't get a spark with the kill switch terminal removed.

Any ideas on the ground tap to armature oh, reading?

Thanks.

 

[greenaccord02]

Put the part back on and and stick a pin in the spark plug wire insulation right next to the body of the unit. Turn it over slowly (but not too slowly) a couple times while holding the pin. If you get shocked, it's a bad wire.

 

[Oldwolf]

It seems to me that the ground tab to armature should not be a closed circuit (0 Ohms), but I am not sure about that. I can't find a schematic of the coils and how it is wound.

Can anyone tell me the answer to this?

The ground tab is essentially already grounded since the resistance is 0.

 

[labman]

I forget what the reading should be. fairly low I think, but 0 indicates a short. A new coil should get it going.

 

[tom slick]

What was the air gap before you pulled it off?

 

[Oldwolf]

A new armature fixed it.

FYI, 0 Ohms is normal for the shut down tab. I wish I had a schematic of the circuit. Anyone have one?

 

[tom slick]

Post the serial number and I'll see if it's in my book

 

[Oldwolf]

Diamond I/C
6HP
Model / Type / Code
12J802 – 2925-E1 98102958


Thanks!

 

[wander2039]

I have a B&S book but since it's a 98 model I'm fairly sure it's not in it. Don't have much time in the next couple day but if Tom doesn't find it I'll double check.

Edit: Have you checked B&S's website they have a bunch of stuff up there now.

 

[greenaccord02]

Part number 802574 is the coil per the IPL for that engine on B&S website.

Search the Part # on ebay and you'll find plenty of them for ~$20.

 

[tom slick]

I had 2 strikes against me trying to give you a wiring diagram. Fist my book isn't new enough and second it doesn't have B&S wiring diagrams. Sorry.

 

[Oldwolf]

Thanks for trying Tom!

 

[F111A]

I have 20 year old John Deere walk behind Silver model w/Kaw engine. Mind did the same thing this year, except it turned out to be the solid state "points/condenser" potted expensive postage stamp sized dingus-adapter. It was cheaper than the coil and the service manager said 95% of the time it's that piece.
I just hope the one for my tractor doesn't V-twin over $400. At least in 10 times bigger, but still. frustrating when you have a electronic back ground and you can't find enough info to rebuild these devices!!!

 

[Oldwolf]

The B&S don't have points anymore either. The electronics are potted into the coil assembly.