Briggs & Stratton ignition

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Old 02-24-19, 11:05 AM
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Briggs & Stratton ignition

It's a Vanguard V twin, model 294447, on a generator. No spark. There is a terminal in each coil that goes back to the switch and from the switch to ground to shut the engine off. Am I correct in thinking that there should be no continuity between this terminal and ground? If I do have continuity between this terminal and the ground, I assume the coil is bad. Is this correct? Thank you.
 
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Old 02-24-19, 01:39 PM
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Best thing to do is disconnect the kill wire (that goes back to the switch) at the coils and see if you get spark. If so the coils are good and the problem is in the kill wiring. That could be grounding at the switch, on the run of the wires between the switch and coils or at a diode in the wiring harness. Usually when the latter is the problem you have a poorly running engine with an erratic spark.
 
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Old 02-24-19, 02:24 PM
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I did check the wire back to the switch, several times, with a meter, and both the switch and the wire are good and doing just what they should. But that check has now led to an interesting finding. Two identical coils obviously, and the grounding terminals connected together, I have two almost opposite results. On coil #1, with the grounding lug connected, and the switch in the start position, I have good spark. When I release the switch, allowing it to return to the run position, I still have spark as long as the engine continues to turn on its' own momentum. So good so far. But if I press the start button, get the engine turning, and move it immediately to the off position, I continue to have spark for as long as the engine continues to turn on its' own momentum. To me, this seems to point to the coil being bad. Then, on coil #2, I have spark as long as nothing is connected to the terminal, but when I harness it with coil #1 I have no spark. So, thinking as I type, maybe I should start by replacing just coil #1 and see if that removes the problem I'm currently having with coil #2.
 
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Old 02-24-19, 03:01 PM
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That probably has to do with the diode in the kill circuit. With both kill wires disconnected, does the engine run normally, although you have no way to kill the ignition? If it does, don't change coils, look at the kill harness.
 
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Old 02-24-19, 03:08 PM
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Yes, I did try that, and it runs fine with both kill wires disconnected, although, as you said, can't kill it so I shut it off via the fuel valve. Had not thought about a diode, and thought that I had looked things over real good, but that makes real good sense so will investigate further. Thank you very much.
 
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Old 02-24-19, 03:12 PM
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No problem. Sounds like a diode. Shows up here a lot. You may have to replace the kill harness as an assembly. Some of the diodes are integrated and not replaceable by themselves.
 
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Old 02-24-19, 11:28 PM
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I agree, your coils are fine, it's the diode(s) in the kill wires.
 
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Old 02-25-19, 09:04 AM
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Yup, thank you very much guys. I really appreciate it. I am absolutely certain that you are right. Should have thought of that myself as Iíve worked on a number of small engines, but personally have only ran into this particular issue once or twice that I recall, so it was way way back in my memory bank.
 
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