Is my B&S coil dead?

bradcdavis00 · 09-13-2009, 06:19 PM

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!

bradcdavis00 · 09-14-2009, 07:24 AM

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.

**octaneman** · 09-14-2009, 07:45 AM

Hi bradcdavis00

The meter readings you got on the coil are normal, coils are between 2.5 and 5k ohms. If the meter would have registered infinity then it would be bad. Re-install the coil and adjust the air gap. Do not connect the tab wire, then re-check for spark, if spark is present, then the switch is faulty. Be careful when you do this, the engine may start and you will not be able to shut the engine off. Check the flywheel key to see if it's sheared.

bradcdavis00 · 09-14-2009, 07:55 AM

Hi octaneman-

The ground tab to armature (I.E. ground) should be 0 ohms? That seems to me to be an already grounded condition and I though perhaps it was shorted which explained the no start condition.

Thanks for your reply. I will put it back together tonight with the tab wire not connected and see what happens.

My grass is getting taller by the minute.

-Brad

bradcdavis00 · 09-15-2009, 07:20 AM

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?

k2skier · 09-16-2009, 09:45 AM

All winding circuits go to ground, there is no meter check for the coil, only test is to remove the shorting wire to the coil and test for spark, as per factory B&S manual.

bradcdavis00 · 09-16-2009, 10:07 AM

B&S Coil Testing

09-13-2009, 06:19 PM	#1 (permalink)
bradcdavis00 Registered User Join Date: Sep 2009 Posts: 5 OS: xp	Is my B&S coil dead? 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!

09-14-2009, 07:24 AM	#2 (permalink)
bradcdavis00 Registered User Join Date: Sep 2009 Posts: 5 OS: xp	Re: Is my B&S coil dead? 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.

09-14-2009, 07:45 AM	#3 (permalink)
octaneman Mentor Home Support, Gearhead Automotive Center Join Date: May 2009 Posts: 541 OS: WINXP	Re: Is my B&S coil dead? Hi bradcdavis00 The meter readings you got on the coil are normal, coils are between 2.5 and 5k ohms. If the meter would have registered infinity then it would be bad. Re-install the coil and adjust the air gap. Do not connect the tab wire, then re-check for spark, if spark is present, then the switch is faulty. Be careful when you do this, the engine may start and you will not be able to shut the engine off. Check the flywheel key to see if it's sheared. Last edited by octaneman; 09-14-2009 at 07:46 AM.

09-14-2009, 07:55 AM	#4 (permalink)
bradcdavis00 Registered User Join Date: Sep 2009 Posts: 5 OS: xp	Re: Is my B&S coil dead? Hi octaneman- The ground tab to armature (I.E. ground) should be 0 ohms? That seems to me to be an already grounded condition and I though perhaps it was shorted which explained the no start condition. Thanks for your reply. I will put it back together tonight with the tab wire not connected and see what happens. My grass is getting taller by the minute. -Brad

09-15-2009, 07:20 AM	#5 (permalink)
bradcdavis00 Registered User Join Date: Sep 2009 Posts: 5 OS: xp	Re: Is my B&S coil dead? 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?

09-16-2009, 09:45 AM	#6 (permalink)
k2skier Registered User Join Date: Sep 2008 Location: Oregon Posts: 313 OS: XP Home-SP3 My System	Re: Is my B&S coil dead? All winding circuits go to ground, there is no meter check for the coil, only test is to remove the shorting wire to the coil and test for spark, as per factory B&S manual.

09-16-2009, 10:07 AM	#7 (permalink)
bradcdavis00 Registered User Join Date: Sep 2009 Posts: 5 OS: xp	Re: Is my B&S coil dead? B&S Coil Testing