mower starts only when spark plug connection is removed but near (picture attached)

S

stevenisam

Forum Newbie
Hi All,

I have a craftsman mower with a Briggs & Stratton engine. This is pretty old mower. This year I changed the spark plug and since then it needs a starter fluid to start. Today it wouldn't start, so i removed the spark plug, cleaned it and sprayed the starter fluild into the cylinder and it started. Only then I realized that I didn't connect the spark plug wire. It was running with the wire right next to the spark plug. Once i connect the spark plug, it never starts.

it starts if I remove the spark plug connection and it won;t start if I connect. I do understand about IC engines to some extend. Any help is much appreciated. Pictures attached.

Thanks in advance,
 

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That is because you have either the wrong plug or the plug has gone bad.
Run the engine for about 10 minutes then cut off the fuel supply to stop the engine.
Replace the plug lead & try again.
If no joy double check the plug.
Most engines with a hall effect triggered magneto take a resistor plug where as points ignitions generally use a plain plug ( no R in the grade ).
 
bertsmobile1 said:
That is because you have either the wrong plug or the plug has gone bad.
Run the engine for about 10 minutes then cut off the fuel supply to stop the engine.
Replace the plug lead & try again.
If no joy double check the plug.
Most engines with a hall effect triggered magneto take a resistor plug where as points ignitions generally use a plain plug ( no R in the grade ).
Click to expand...

Thank you, I will probably replace the plug and try as you suggested. I also notice that there's black smoke coming since I changed the plug.
 
Modern fuel, which is nothing like petrol , is very conductive at cylinder pressures.
Thus the spark will run down the side and ground out at the bottom of the insulator rather than jump the gap.
Holding the lead off the plug forces the voltage to build up to a higher amount before it can get to ground through the plug thus when the higher voltage hits the electrode it will jump the gap & fire the engine.
If your carb is flooding the engine then the plug will always be wet.
An old adage goes
Most ignition problems start in he carburettor
Most carburettor problems start in the ignition.

A magneto does not produce a fixed voltage, the voltage varies with the speed the magnets pass the coil .
Most of them will spark well before peak voltage is reached.
 
Steven can you post a pic of the mower it's on ??? I remember the old Yazoo mowers with the horizontal Briggs on them.......

Great bullet proof mowers......

Plus Tard Mon Ami ~!~!
 
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