If you're using an inline spark tester, it does not test the plug. Joed said
"Keep in mind, the spark tester will tell you the whole ignition system is good or bad EXCEPT the spark plug."
The coil fires a very high voltage, which can light the tester, even if it's not grounded. Try a new plug.
"Keep in mind, the spark tester will tell you the whole ignition system is good or bad EXCEPT the spark plug."
The coil fires a very high voltage, which can light the tester, even if it's not grounded. Try a new plug.