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Scott Salmons

Weak Spark

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Scott Salmons
I was out mowing and vacuuming this afternoon and I was admiring how well the B-112 was running, about that time it was like I shut the key off. The first thing I checked was spark. I can hold the wire while cranking a get a slight jolt but not enough tho light the plug. I tried a couple of different plugs I change condensor and even put in a different set of points. I never ran into this before, it was either spark or no spark. Any suggestions? Thanks

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harrya
Please,expain to me how two wires atached to the out side of the points cover box shorts out the points.I"m just trying to get my mind around this? And understand the system. Considering converting to an atumotive system. Any help would be great.!!

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UCD
One black wire comes from coil and connects to the points inside of points box. Second black wire comes from coil and is connected to a terminal block mounted to the top screw of the points cover. A third white wire is connected to the black wire on this terminal block and goes to the key switch. When the switch is on this wire is open. When the switch is off it puts a ground on this wire shorting the points and coil to ground shutting of the engine. The switch is grounded internally

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UCD
There is only one wire going into the points box to the points. The other wire is to a terminal block on out side of cover. One wire (Black) from the coil to the points inside the points box to fire the points. One wire (Black) from coil to terminal block on out side of points box cover. one wire (White) from Ignition switch to terminal block on out side of points box cover.

The ignition Switch is convenient place to start and stop engine. You have to have a second wire from the switch. the connection point on the out side of the points box is an easier access point for testing purposes. Instead of removing battery and or gas tank to get to Ignition switch or removing engine cover to get to coil you break connection at terminal block and test both ways. Less chance for a second wire to ground out going under the points cover. The ignition switch is grounded when the switch is in the off position this puts a ground on the white wire in turn putting a short to ground on the coil killing the engine. The other method of shutting engine off is to ground the Spark plug with a grounding strap that you push against the spark plug.

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harrya
I called JACKS SMALL ENGINE TO ORDER PARTS TO CONVERT TO 12 V EGNITION. Gal did"nt have clue what i was talking about. I gave her part # I got off KEN WILLIAMS POST. Any help would be great,or does anyone know who to ask for at JSE.

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Al
Hi, I agree with the above, remove the kill wire from the key switch, if still no spark, run something like a business card or a burnishing tool between the points. Still no spark. Good chance you partially sheared a flywheel key. If you are pulling the dech and a vac, any surge or shock like hitting a stick might be enough to partialy shear it and then you can or will have weak or no spark, depending on how bad. Keep in mind that on newer tractors with electronic ignition, with a sheared key, they will still have hot spark, it will not be at the correct time. Ex. It might actually be firing at the bottom of the stroke and will not run. With points the inductance of the magnetic field of the flywheel must be in sync with the points breaking. If this doesn't happen then NO SPARK. My thoughts. Al Eden

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johnmonkey
Speaking of weak spark, is there a reason that a Briggs model 19d will not accept a mega-fire ignition module? I have a model 19d and did convert it to a battery ignition with an automotive type coil with the internal type resister. The spark is again weak, I think due to a worn points plunger. I am ready to convert to a megafire ignition if it will work. JH

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