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sammiefish

coil and no spark?

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sammiefish
I have a AC 312 that ive been having trouble with the key switch... after much trouble wiring... I dont have spark...(I used to!!!) While I know anything is possible... Is it likely (or for certain) if I leaked 12V to the + side of the coil (the wire that grounds to turn the tractor off) should I have blown the coil or condenser? grrr.... also, is there a resistor in the key 5 blade key switch where the coil grounds to turn the motor off? if not where is the resistor located?

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midnightpumpkin
I should ask first if we are talking a Briggs engine or a Kohler. On a Briggs, if you accidentaly connected +12V to the wire that grounds the points to kill the engine, you probably fried the coil in the magneto. Can't comment on a Kohler. If this is the case, the simplest fix is to set it up with an external coil and ballast resistor. The how to is documented here on this site. Do a search on external coil. John U

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D-17_Dave
312 uses a Kohler engine which uses a 12 vdc voltage induced coil. Putting 12vdc to the + side of the coil is the same as turning the key switch to the on position.

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D-17_Dave
quote:
Originally posted by midnightpumpkin
Am I correct in thinking that the ballast resistor is built into the Kohler coil?? John U
As a rule of thumb, most late model coils have a resistor built in. About the only automotive style coil that I know of that doesn't have it built in is a coil for a 70's and earlier model Dodge/Chrysler coil. As they had the resistor mounted to the fire wall. Now some external coils made for ag/industrial applications varied. While some type of voltage control for points longevity is needed, a coil with an external resistor adds an extra component but used properly with a starting bypass loop from the solenoid will give the coil a boost in the start mode and provide a real good spark for easier starting. This is what I'd probably use if I had a choice.

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sammiefish
sorry, I have a Kohler... the + side of the coil connects to the condenser and to the key switch (to kill the engine)... my concern is that I connected the lead to the wrong blade connector on the key switch possibly feeding it with 12V. the - connector on the coil goes to the points. So, could I have blown the coil or the condenser by doing this? It seems that is where voltage should go... but I suddenly dont have spark so...??? now that i look more closely... it looks like someone may have wired the condenser to the + side of the coil... tapping off the black wire going to the key switch... wow... strange...


I do have another coil (and a stator), but it is from a Wheel Horse and on the outside of the coil it is written that an external resistor must be used. Can anyone tell me what size or type of resistor I am looking for here? Or maybe I am looking for another coil??

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Dark


Voltages just after the points open may reach 250 volts because of the amount of energy stored in the primary windings and the subsequent magnetic field. A condenser which is defective or improperly grounded will not absorb the shock from the fast-moving stream of electricity when the points open and the current can force its way across the point gap, causing pitting and burning. All electrical circuits require voltage to operate the components connected to that circuit. So if there is no voltage, there is no function. The first order of business when troubleshooting electrical problems, therefore, is to check for the presence of voltage at the load point(positive side of coil) in the circuit. Suppose you find no voltage at the load point. Ah ha, you have discovered your first clue about the problem. Check the ignition switch and the fuse a 12v test light can be used for quick checks but a voltmeter is recommended.

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sammiefish
this is indeed very helpful... as you may have seen in my other post apparently I have the wrong switch. Im hoping that this solves my problem as I was not finding voltage on the switch blades where it should have been... thanks so much for the help!! Ill keep you posted on what unfolds.

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powerking_one
Chris, With battery ignition systems, the condenser always connects to the same terminal as the points. On a 12v negative ground setup, the points and condenser wires would connect to the (-) side of the coil. Then +12v would attach to the (+)side; hot when the ignition switch is in the on/run position and start position. In the off position, the wire on the (+) coil terminal would be zero volts and open circuit/infinate resistance. Tom (PK)

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sammiefish
UPDATE: while I havent even looked at the coil wiring yet... I received my new key switch in the mailbox when I got home today..... 5 minutes later.... the starter is turning over the engine, and I have spark Ill check the rest of the wiring tomorrow maybe she runs!!

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