Electrical – Diagnosing faulty ignition coil on lawn tractor

electricalenginelawn-mowerrepair

Model: 13AM662F765 Engine Model: 283H07-0197-E1

I have an MTD lawn tractor, circa 2004, that hasn't been running quite right. The mower runs for about 10 minutes and suddenly stall. I would turn the key once and the engine would backfire. Turn the key again and it would start running again. After the initial stall, the mower only runs for a minute or two before stalling again. After running through some basic troubleshooting — replacing spark plug, replacing fuel, checked fuel filter, checked air filter and few other things. I've finally arrived at the ignition coil and I believe it needs replaced. The spark at the plug appeared weak, so I tested the coil for continuity and didn't get a reading. I'm assuming that faulty wiring in the coil isn't producing the necessary spark.

It's several days later and I've since received a replacement coil. The new coil is much smaller, so I'm not sure this is the correct part. Tested the resistance on the new coil (10-12Ω). I decided to retest the old coil and this time got a reading of 4-6Ω. Why is there a difference in the resistance? Does it mean the old coil is faulty and the reason for the weak spark?

coils

Replacement part: https://www.homedepot.com/p/Briggs-Stratton-Magneto-Armature-591459/205448695

Best Answer

It sounds like the coil goes open circuit when it gets hot. That's why you didn't get a reading when you tested it post-failure, but now you do.

I would say go ahead and install the coil. 15 years is plenty of time for the manufacturer to change the design of the coil, while still being compatible.