8237 SER 9424117 Ignition CD coil questions?

[2cyclegreenmachines]

Just finished rebuilding this engine. Everything reassembled and I have no spark when I tried to start it. This is a 1979 non-compliant mower with the ground to run switch on the top of the shroud. Old ignition coil has the number 681410 molded into the white plastic next to the spark plug lead. Is there a way to bench test this module? I had no spark and the small ground lead terminal has conductivity to cylinder fin ground with the switch in on or off position. I have found two other coil numbers that show to be compatible on the parts supplier sites, 681578 and 100-2949. I have a 100-2948 and a 100-2949 module both have black plastic. The new modules I think are both for newer compliant mowers, ground terminal to shut off. The 2949 has the mounting holes and mag pick up blocks in the correct place, the 2948 has both different mounting hole and mag pick up block positions.

 

[StarTech]

Small engine CDI ignition are basically plug and play. Not possible to test other than actual use. YOu remove the kill lead and see if it fires when the engine is cranked no fire bad coil. It is rare the flywheel magnets becomes demagnetized.

 

[Hammermechanicman]

Some lawn boy coils are ground to run and some ground to kill. The older coils were very bad about killing the coil if engine was cranked with the plug wire disconnected. I have replaced a ground to run coil with a ground to kill type. Been 20+ years ago so i don't remember part numbers. They looked the same just a different color.

 

[StarTech]

Tnx for that info. I was unaware of a ground to run type and never came across such setup. I rarely come across old LB mowers as most are done been recycled here.