Testing Ignition Coil

[dennis]

I suspect the coil on my Briggs and Stratton engine may be defective. I would like to know how to check the primary and secondary circuits, and the specs. B&S Model 126T02, Type 0675-B2, Code 08081958. Any help would be appreciated. Thanks.

[StarTech]

Basically you can't test the electronics of the coil but there is an article in the Downloads > Briggs and Stratton Service Info > Advance Product Service Info > Briggs Magnetron Coils - New Versions.pdf that cover some the basic internal info.

[RoyM]

X2 Are you checking it with a spark tester (best method) or a known good plug that is properly gapped? Is the air gap set at .010"?

[KE4AVB]

Even with a spark tester it only shows it is triggering and firing. Now especially with verticals on walk behinds a partially sheared flywheel key can throw off the ignition timing to cause strange problems. Also with electronics in the coil the timing can shift out out the normal timing advance range as the coil is heated or when there is a failure in the electronics. Also the flywheel must be properly torque and the area under the shroud must be free of debris especially mouse beds.

Now that you think you might have a coil failure what are your symptoms?

Even if you replace the coil and this one especially you will need a new air vane if one is use as coil configuration has changed per the ipl.

I have seen some pretty out of ordinary coil's electronics failures from simple failures to one that sets the air filter on fire or trying to set your pants leg on fire. I have seen them to random misfire. The only thing you can do if you suspect a coil failure is to install either install a known good used coil or a new one and test.

[Skywatcher]

Hi Dennis

Looking at the IPL of your engine, it appears to have the metal shielded spark plug cap (B&S part # 793351) on the end of the plug lead. These caps seem to fail quite often, so I keep 3 in stock. The cap will pull off the end of the lead, you may need to spritz a little silicone spray lube between the rubber cuff and the lead in order to get it off. Once you have this cap off, repeat the spark test directly on the end of the lead. If you have spark, replace the cap. You can test the resistance of the primary and secondary windings, but there's no way of checking the trigger coil or the switching transister. Primary winding resistance is usually 0.5 to 3.0 ohms and secondary winding is usually in the 3,000 to 7,000 ohms range. If you need a new coil, B&S part # is 590454. Hope this points you in the right direction,

Sky

[dennis]

Thanks for all the responses.

The problem I have is that the engine started and ran...I let it warm up well because it has the thermsostat/air vane-operated choke. Then I stopped it and let it set for a minute. Started it, and it ran for about 30 seconds and quit. Then could not start it. Checked the spark with a spark-tester, and with another spark plug. No spark. Am planning on checking primary and secondary wires for shorting, and flywheel brake switch. Will also check flywheel key. Will also check the metal shielded spark plug cap.

[38racing]

on this model can't you just disconnect the kill wire from coil to verify the coil itself?

[KE4AVB]

Yes that isolates the kill circuits from the coil.

Dennis sounds like me he is wanting to know the exact cause instead of just swapping parts and hoping he get it right.

I currently have an out the ordinary ignition problem with a Kohler v-twin on Hustler ZTR myself that I trying to figure out if I have a dual coil failure on or not. Since it off topic of this thread so I not adding to the confusion; I just started working on it and I am coming up with ideas to try out after the rain ends.

[dennis]

Well folks, finally found out what the "no spark"," intermittent spark" problem was. The little nylon?-based kill switch that is mounted on the flywheel brake bracket was warn and somewhat floppy. It would make or break contact when it felt like it. I put a new one in, nice and tight, and that fixed it. Thanks for all the good information.

[KE4AVB]

Tnx for the update and glad you found your problem as I did with the KT745.

I actually got my first dual coils failure. Kohler tech support confirmed my diagnosis. None of the local dealers that I have contacted will honor Kohler warranty of them; unless, I haul in the Hustler 60" ZTR to their shop which is completely unnecessary just to warranty replace the parts.