MTD 115/76 Tecumseh 12.5 HP OHV Carburettor Issue

[Rivets]

You just tested it the way 95% of the techs on this sire do it.

 

[hlw49]

You sdid. I couldn't get any sign of a spark, so replaced the coil & spark plug but still no joy. Even removing the kill switch wire doesn't make any difference. Terry. There is no other way to test the ign module. Once you disconnect the kill wire and spin the engine over and check it with a spark tester and get no fire you have a bad coil. They either work or they don't work.

 

[bertsmobile1]

Out of curiosity can the coil be put on the other way round ?
The hall effect chip is polarity sensitive so the voltage generated in the coil generated has to be negative 0 then positive if it is + 0 - then you will get no spark
The only other thing is a bad magnet in the flywheel . very rare for this to happen .

 

[JBASport]

Hi, thanks. I tried flipping the coil and still no spark. I think the magnet on the flwheel is ok as it grabs the coil when fitting & is difficult to prise apart to set the air gap. Thanks, Terry

 

[JBASport]

Hi, I have tried flipping it but still no spark. I think the flywheel magnet is ok, as when I fit the coil it grabs the magnet hard against the flywheel, making it difficult to separate. Thanks, Terry

Hi, thanks. I tried flipping the coil and still no spark. I think the magnet on the flwheel is ok as it grabs the coil when fitting & is difficult to prise apart to set the air gap. Thanks, Terry

I have bought 2 new coils (from different suppliers) and still cannot get a spark! Both were matched against the engine type/serial number. The magnets on the flwheel seem to be strong, as when I fit the new coils the magnetism grabs the coil against the magnets on the flyweel and makes it difficult to set the air gap. Not knowing how strong the magnets should be, is it possible to increase the strength of magnets by rubbing a stronger magnet against the ones on the flywheel? Other than that I am at a loss as to what to do next to get a spark! Thanks, Terry

 

[Mark H_NO]

The only way I know to test the coil is to test for spark. Use a spark tester, or remove the plug, connect the plug wire, and ground the plug. Don't hold the plug in your hand, or you can get shocked. Have someone else pull the cord, and watch for spark. There may be a test with a good voltmeter, but I don't know about it.

 

[JBASport]

Thanks Mark

The only way I know to test the coil is to test for spark. Use a spark tester, or remove the plug, connect the plug wire, and ground the plug. Don't hold the plug in your hand, or you can get shocked. Have someone else pull the cord, and watch for spark. There may be a test with a good voltmeter, but I don't know about it.

 

[Mark H_NO]

Fuel, compression, spark, and timing are what you need to run. If you're doing this to check spark, it may be a good idea to check the flywheel key. It can be sheared by suddenly stopping the blade(hitting a big root hard.) Take the nut and washer off the flywheel, it's pretty easy to see it's sheared. Here's an example.

 

[JBASport]

Fuel, compression, spark, and timing are what you need to run. If you're doing this to check spark, it may be a good idea to check the flywheel key. It can be sheared by suddenly stopping the blade(hitting a big root hard.) Take the nut and washer off the flywheel, it's pretty easy to see it's sheared. Here's an example.View attachment 69090

Thanks for that, will check that out & have also ordered an OEM coil just to be sure. Terry

 

[Mark H_NO]

Make sure you don't get lube on the flywheel or shaft if you pull it, that can cause the key to be sheared.