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16HP Briggs Has No Spark


Fordwizkid's Avatar
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06-13-08, 07:24 AM   #1  
16HP Briggs Has No Spark

I am a mechanic by trade, and for the moment feel very defeated from this little motor I was givin a 2004 Murray riding mower with a 16HP Briggs Twin Cylinder engine (402707,124001). When I recevied it I was told it needed a starter, and infact it did since the previous owner had removed it, and did not give it to me. I put a brand new starter on it, charged the battery, replaced the fuel filter, and put in some fresh gas. When I hit the key all I got was the notorious clunk from the starter solenoid. So back to the store to buy a new solenoid. After the install, and a few seconds of cranking she fired up, and seem to run pretty good for how long it had been sitting. I shut it down to check for leaks, and such then restarted to check if the deck would engage. The motor kept trying to die so again I shut it down, and found the safety switch disconnected under the seat, and a bunch of debris under the deck switch. Cleaned it all up, and now it will not start. I have no spark whatsoever. First place I went to was the kill switch wire on the coil, and disconnected it...still nothing. Upon further inspection I noticed the coil was very very warm and the windings were comeing out of the back of the casing. I bought a new Briggs & Stratton coil and installed it right side up, and adjusted the air gap with a bussiness card as well as cleaned the rust off the flywheel. STILL NO SPARK !! I have the kill switch wire dissconnected, and the motor seems to be spinning quickly. The magnet in the flywheel is not loose, and the plugs are relatively clean. The only thing I can think of is that the battery is low on cranking amps, and the starter is robbing them all. I have checked everything I know of, and need some help ! Please give me some ideas of what I should do next. Thanks in advance !!

 
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06-13-08, 10:26 AM   #2  
When the flywheel turns with a good coil, and no kill wire
connected, there should be spark.

What destroys these coils, is voltage sent to them via the kill wire, and that sounds like what definitely killed your
old one, and if you hooked the kill wire to the new one,
even for a second, destroyed the new one too.

What shuts the engine down, when turning the key to the off
position, is the kill wire going to ground, shorting out the
circuit. No voltage should be on this wire. A bad keyswitch,
melted wiring, wrong keyswitch, etc., can cause this.
Fish

 
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06-13-08, 10:42 AM   #3  
I really hope thats not the case considering the coil cost $50. One thing I did check was for power on the kill switch wire with the key in the on position, and when cranking when the old coil was still on it and there was no voltage at that time. I know I did plug it up after I put the new one on, and attempted to start it. I suppose there is no way to be sure unless I replace the ignition, and the coil, and try again I do know none of the connecters on the mower are damaged or melted, and I did check all the wiring.

 
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06-13-08, 10:41 PM   #4  
IF....there is no power to the coil kill wire and never has been, then I'm going to take a guess and say the coil is upside down, or it is not an original briggs coil. The kill wire connector should be on the bottom side of the coil. If it is up top, it's upside down and won't fire that way.

From the description of the windings popping out of the old coil, it does sound like it had power to the kill wire. I'm sure of it, by that description. Hopefully that hasn't happened on your new coil.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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06-14-08, 05:16 AM   #5  
It's deffinetly a Briggs coil, and is labeled this side out so it is infact on correctly. I went ahead, and swapped out the ignition switch last night, and pulled the plugs out. I put a battery charger on it, and still nothing. Before I buy another new coil is there anything else that could be the culprit ? The magnet on the flywheel seems strong so I am guessing thats not the problem ?

 
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06-14-08, 05:38 AM   #6  
No, other than the magnets, nothing else. And in 19 years, I have not seen a flywheel lose it's magnetism.

Just make sure you find that voltage source.

You made sure you put on the correct keyswitch? Most of
them look identical.


Fish

 
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06-14-08, 08:46 AM   #7  
Well I kinda lucked out. The fella up at the parts store was kind enough to swap out the coil I just bought for another after I explained to him what may have happend. Considering almost nobody will take back any electrical parts I certainly appreciated it. I am gonna try again with this one, and make sure I leave the kill switch wire off until I can double check on the ignition switch I just put it. I'll let ya'll know how I make out on monday. Thanks for the advice, and knowledge... Hopefully this will take care of my problem !!

 
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06-16-08, 04:28 AM   #8  
Well lesson learned.... It was the new coil after all. I made sure I had the right ignition switch, and she fired right up ! Should be ready to cut grass this weekend after a carb rebuild. Thanks guys !!

 
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06-16-08, 08:15 PM   #9  
Was the switch sending power to it? Glad you got it, and thanks for the update!


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

 
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