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no spark on plug

#1

B

bigyardguy

B&S on Troybilt lawn tractor. 17.5 HP. Just quit one day. Thought had water in gas but no. replaced plug with good gap. Magnetic coil is sparking at plug end but plug does not spark. Any ideas.


#2

ILENGINE

ILENGINE

First disconnect the ground wire from the coil and recheck for spark, just to make sure there isn't a partial short in the kill circuit. if that doesn't fix the problem, most likely it is a coil going bad and will need to be replaced. just to be safe, hook a meter between the ground wire, and the engine frame, and turn the key on and off several times just to make sure there isn't any power getting to the coil.


#3

G

gregjo1948

bigyardguy said:
B&S on Troybilt lawn tractor. 17.5 HP. Just quit one day. Thought had water in gas but no. replaced plug with good gap. Magnetic coil is sparking at plug end but plug does not spark. Any ideas.
Click to expand...

Not sure what you're saying "sparking at plug end but plug does not spark". If you mean, where you attach the plug to the wire,it is sparking and when you attach the plug, the plug doesn't spark, it's probably a faulty plug. gregjo1948


#4

G

gpugh1

I'm having the exact same problem and I replaced the plug twice and the mower will crank right away but once I shut it off and try again the next day, it will not start. There is a spark at the plug wire but not at the plug.


#5

Mike88se

Mike88se

ILENGINE said:
First disconnect the ground wire from the coil and recheck for spark, just to make sure there isn't a partial short in the kill circuit. if that doesn't fix the problem, most likely it is a coil going bad and will need to be replaced. just to be safe, hook a meter between the ground wire, and the engine frame, and turn the key on and off several times just to make sure there isn't any power getting to the coil.
Click to expand...
:thumbsup:
Not much to add to that good info except make sure you have the correct plug, the boot is good, and learn to read plugs.


#6

gfp55

gfp55

bigyardguy said:
B&S on Troybilt lawn tractor. 17.5 HP. Just quit one day. Thought had water in gas but no. replaced plug with good gap. Magnetic coil is sparking at plug end but plug does not spark. Any ideas.
Click to expand...


This may sound like a stupid question, but when you check for spark at the plug, the plug is in the wire boot and the plug is grounded to the engine right? Is it a good strong spark? Is the old plug black and smell like gas? Maybe try gaping the plug .025 instead of .030 or gap it just a little less then what it calls for.


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