I inherited a 22 inch push mower with a B&S 3.75HP engine. When I first tried it there was no spark. After removing the stop engine ground lead, still no spark. Assummed a bad ignition module. $40 later, installed new ignition module (OEM brand new out of the box) still no spark. How critical is magnet strength (they seem plenty strong) ? What about air gap (used cardboard from box, approx .01) ? How likely is it that ignition module was bad out of the box?

Stumped in PA.

did you try a different sparkplug

well, new coils can be bad, they are mass produced, check the gap with a dollar bill, it must have resistence when pulling it out, but still enough to get it out, then check it for catching, the magnets should be able to pull a screwdriver for instance, in from a inch or so away. does this use a point and condensor system, or is it not that old? well to make sure, if its newer, the only wire to it is the kill wire, other then that, you'd still get spark out of a sheared key, but it wouldn't run if the key was sheared, how are you checking the spark???

make sure your not mounting the coil upside down. that will produce no spark as well.

oh yes, forgot about that one, should say this side out on the coil. which sometimes some can overlook.