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Spark plug not grounding??
- Thread starter joec1234
- Start date
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Export threadJust watched your video, which I normally don’t do, and see some concerns. First, get rid of that ground wire you are using. Absolutely no need for doing any tests. Second, you don’t say whether you reset the armature air gap to .010”. Third, remove the kill wire from the coil. Now, plug your spark tester into the coil wire and hold the other end to a good ground on the engine. Turn the engine over, do you have spark? NO, bad coil. YES, proceed. Now attach the spark tester to the plug. Turn the engine over, do you have spark? NO, bad coil. YES, proceed. Reattach kill wire to coil. Turn the engine over, do you have spark? NO, bad kill wire. YES, engine should start. Report back results.
Just watched your video, which I normally don’t do, and see some concerns. First, get rid of that ground wire you are using. Absolutely no need for doing any tests. Second, you don’t say whether you reset the armature air gap to .010”. Third, remove the kill wire from the coil. Now, plug your spark tester into the coil wire and hold the other end to a good ground on the engine. Turn the engine over, do you have spark? NO, bad coil. YES, proceed. Now attach the spark tester to the plug. Turn the engine over, do you have spark? NO, bad coil. YES, proceed. Reattach kill wire to coil. Turn the engine over, do you have spark? NO, bad kill wire. YES, engine should start. Report back results.
Okay so the engine fires when the Kill wire is disconnected. I believe that would be a bad ignition?
bertsmobile1
Lawn Royalty
- Joined
- Nov 29, 2014
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- 24,995
I rarely watch videos either as we have rubbish internet down here & have very limited downloads.
Firstly if you are going to play at repairing mowers please do some basic learning.
Lots of "how to" books that explain how things work.
1) the wire that you are calling a ground wire on the coil is the kill wire
When running it should be open circuit , no voltage & no ground
2) the spark plug IS A GROUND CONNECTION for the coil with a gap in it so the electricity has to jump across the gap .
Putting a wire on the top of the plug simply makes another ground connection bypassing the spark plug gap.
In a electrical circuit, an air gap is a resistance, the bigger the gap the higher the resistance
The higher the resistance the more voltage is needed to overcome it.
So if you connect your tester directly to the engine by putting a BYPASS JUMPER on the top of the spark plug and it lights up but it will not light up when connected to the spark plug the output voltage of the coil is too low to jump the gap.
Electrically with that wire there it is the same as putting your tester between the HT wire and the block.
If you get some really old mowers in for repair you will see a tab that sits over the spark plug which the operator pushed down onto the spark plug to stop the engine by bypassing the spark plug.
There are 5 reasons for a coil which will light up to the block but not through a good plug.
1) wrong coil
2) coil on upside down
3) magnets weak
4) coil air gap too large
5) bad ground connection between the coil and the mower
Firstly if you are going to play at repairing mowers please do some basic learning.
Lots of "how to" books that explain how things work.
1) the wire that you are calling a ground wire on the coil is the kill wire
When running it should be open circuit , no voltage & no ground
2) the spark plug IS A GROUND CONNECTION for the coil with a gap in it so the electricity has to jump across the gap .
Putting a wire on the top of the plug simply makes another ground connection bypassing the spark plug gap.
In a electrical circuit, an air gap is a resistance, the bigger the gap the higher the resistance
The higher the resistance the more voltage is needed to overcome it.
So if you connect your tester directly to the engine by putting a BYPASS JUMPER on the top of the spark plug and it lights up but it will not light up when connected to the spark plug the output voltage of the coil is too low to jump the gap.
Electrically with that wire there it is the same as putting your tester between the HT wire and the block.
If you get some really old mowers in for repair you will see a tab that sits over the spark plug which the operator pushed down onto the spark plug to stop the engine by bypassing the spark plug.
There are 5 reasons for a coil which will light up to the block but not through a good plug.
1) wrong coil
2) coil on upside down
3) magnets weak
4) coil air gap too large
5) bad ground connection between the coil and the mower