So I have a mower that runs well. No issues there. It was barely running, but after a cleaned carb and an oil change it fires up on first pull. It's a Briggs & Stratton. I don't have the mower model number on me, but that isn't relevant to my question (I don't think).
I was adjusting the brake lever cable so that the kill switch had a gap (ungrounding it) when the brake lever was pulled. I was testing the magneto ground wire (magneto to kill switch wire) with my multimeter to check for continuity. When I pulled the ground wire from the magneto and used one probe on the magneto end of the wire, and one probe on the other end. I had continuity. Good. And if I moved the second probe across the gap to the contact point for the kill switch, I had no continuity. All good.
Now, if I connected the wire back onto the magneto, still with the brake handle pulled back, and redo the continuity test, except this time using the contact points of the kill switch, there is now continuity (see pics if that doesn't make sense). But there is a gap between the contact points, which means, given my previous tests, the circuit is grounded somewhere between the magneto and the spark plug. When I check for continuity between exposed metal on the mower somewhere and the 'ungrounded' kill switch, I also have continuity. But if that is the case, why does it start? If it is grounded in some other way when the brake lever/handle is pulled back, that should prevent a spark, since there is a more direct route to ground than across the spark plug gap, no?
All tests were obviously done when the mower was not running.
Am I misunderstanding something here, or do I have an issue that somehow does not prevent the mower from starting up?
Again, the mower runs. But I don't understand why, and I would very much like to know. Thanks.
I was adjusting the brake lever cable so that the kill switch had a gap (ungrounding it) when the brake lever was pulled. I was testing the magneto ground wire (magneto to kill switch wire) with my multimeter to check for continuity. When I pulled the ground wire from the magneto and used one probe on the magneto end of the wire, and one probe on the other end. I had continuity. Good. And if I moved the second probe across the gap to the contact point for the kill switch, I had no continuity. All good.
Now, if I connected the wire back onto the magneto, still with the brake handle pulled back, and redo the continuity test, except this time using the contact points of the kill switch, there is now continuity (see pics if that doesn't make sense). But there is a gap between the contact points, which means, given my previous tests, the circuit is grounded somewhere between the magneto and the spark plug. When I check for continuity between exposed metal on the mower somewhere and the 'ungrounded' kill switch, I also have continuity. But if that is the case, why does it start? If it is grounded in some other way when the brake lever/handle is pulled back, that should prevent a spark, since there is a more direct route to ground than across the spark plug gap, no?
All tests were obviously done when the mower was not running.
Am I misunderstanding something here, or do I have an issue that somehow does not prevent the mower from starting up?
Again, the mower runs. But I don't understand why, and I would very much like to know. Thanks.