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Electricity just got confusing

#1

R

Rivets

I know I’m getting old and electrical problems can get very confusing, but in 50+ years I’ve never seen this before. I’ve got an Echo CS346 that I need to get running, I hooked my inline spark tester (neon light) up to check for spark; nothing. Ok, installed new plug; very faint. Pulled the plug, ran a jumper from plug to good ground; faint spark. Disconnected the plug and I don’t know why but I gave the rope one more pull; great spark in tester. Remember I now have good spark without one end of the tester connected to any ground. I must be going nuts, because I can’t understand how I can have current flow on an open circuit???? AIR GROUND??? I know this makes no sense, but I haven’t been drinking this morning and I now think I’ve lost it. Decided to put everything back together and give the saw a try, started to my surprise. After adjusting the carb, the saw is running good and I’m quitting for the day. Can anyone tell me I’m not crazy and give me any explanation? Edit: I tried my other tester, same type, and it also showed spark.


#2

Scrubcadet10

Scrubcadet10

:unsure:


#3

StarTech

StarTech

it because it got one these stupid plug wire terminals.
1717873435790.png
They tend to break the high tension (plug wire) lead internal conductor then make contact sometimes and other times they don't.

Usually you can snip off the section where the hole is and reinstall the terminal.


#4

R

Rivets

It was that style connector, but that doesn’t explain why I show current flow through the tester when one end is connected to the secondary wire and other end is in thin air, not touching anything.


#5

Hammermechanicman

Hammermechanicman

You are applying a mometary high voltage to a glass bulb filled with neon. Enough energy will dissipate into air to excite the gas. It doesn't take that much to excite the neon gas. The air has super high impedance so essentially no current flow. My old school noninductive timing light would work without the plugwire connected to the spark plug but just the timing light.


#6

StarTech

StarTech

Then you will be confused standing under those high tension overhead wires (your local electrical transport system). Underneath them you can hold up florescent light bulb tube (one those four to eight ones) and have it light up. And there no wires attached on either end.

Those neon testers are not really testing for current as much they are just testing the presence of high voltage. Same theory is at work on those non contact voltage testers that they for checking your wall outlets.


#7

R

Rivets

I understand what everyone is saying, it’s just confusing that in all my years of fixing engines I’ve never seen it before. Thank you all for educating this old fart.


#8

J

Joed756

Rivets said:
I know I’m getting old and electrical problems can get very confusing, but in 50+ years I’ve never seen this before. I’ve got an Echo CS346 that I need to get running, I hooked my inline spark tester (neon light) up to check for spark; nothing. Ok, installed new plug; very faint. Pulled the plug, ran a jumper from plug to good ground; faint spark. Disconnected the plug and I don’t know why but I gave the rope one more pull; great spark in tester. Remember I now have good spark without one end of the tester connected to any ground. I must be going nuts, because I can’t understand how I can have current flow on an open circuit???? AIR GROUND??? I know this makes no sense, but I haven’t been drinking this morning and I now think I’ve lost it. Decided to put everything back together and give the saw a try, started to my surprise. After adjusting the carb, the saw is running good and I’m quitting for the day. Can anyone tell me I’m not crazy and give me any explanation? Edit: I tried my other tester, same type, and it also showed spark.
Click to expand...
Without supplying the make, model, and serial number you make it much more difficult for us to troubleshoot.


#9

R

Rivets

Joe, if you read post #1 you will see that I got the unit running. I was just making an observation about electricity which I have not see before. I don’t understand everything posted fully, but I did learn something new.


#10

StarTech

StarTech

Rivets if you don't fix the end of the plug wire it will give trouble in short again.

And Joe Rivets did give the model number of the Echo chainsaw he was playing with...but in this there is two serial breaks but wasn't need for this particular problem.

Now just depend if Rivets has been in my shop or not as a couple bottles of home brew are missing.


#11

R

Rivets

Star, I did repair the terminal. I always remove that spring terminal and use a crimp style with one modification. Take a piece on Ni-Chome wire, bend into a U at least 3/4” on both sides and push into the wire. Then crimp an auto style terminal over the top. Works great especially when you don’t have much wire to work with. Also, I was hoping you didn’t realize that one bottle was missing. Good stuff.


#12

V

VegetiveSteam

Joed756 said:
Without supplying the make, model, and serial number you make it much more difficult for us to troubleshoot.
Click to expand...
😆


#13

R

RevB

StarTech said:
it because it got one these stupid plug wire terminals.
View attachment 68893
They tend to break the high tension (plug wire) lead internal conductor then make contact sometimes and other times they don't.

Usually you can snip off the section where the hole is and reinstall the terminal.
Click to expand...

Get these instead...

NGK (8328) LB01EP Spark Plug Cap , Black


They screw into the plug wire about an inch.
StarTech said:
it because it got one these stupid plug wire terminals.
View attachment 68893
They tend to break the high tension (plug wire) lead internal conductor then make contact sometimes and other times they don't.

Usually you can snip off the section where the hole is and reinstall the terminal.
Click to expand...


#14

Scrubcadet10

Scrubcadet10

RevB said:
Get these instead...

NGK (8328) LB01EP Spark Plug Cap , Black


They screw into the plug wire about an inch.
Click to expand...
I've used those on 4 wheelers and kawasaki mules alot... they are great and have had no issues from them


#15

P

Peva

FYI - You should avoid firing an ignition (whether lawnmower or automotive) without a path to ground either through the specified spark plug gap or direct short to ground.

Here's why: The ignition coil can generate much higher voltage than it takes to fire the properly gapped spark plug. When the spark plug fires, the resistance of the ionized air in the spark plug gap is so low that the coil output voltage can't rise above the voltage that it took to ionize the air in the gap to initiate the spark. When the coil output wire is held out in the air, far from a ground, the voltage rises tens of thousands of volts higher than the spark plug gap allows. The insulation inside the coil cannot withstand that high of a voltage and will arc through the insulation of the coil - which blows a pin hole through the insulation, leaving carbonized (conductive) material coating the inside of that hole - so the coil is now defective - no longer allows the coil output voltage to rise to the ionization voltage of the proper spark plug gap.


#16

Hammermechanicman

Hammermechanicman

The old 2 stroke LawnBoy mowers were very bad for blowing coils if the plug wire wasn't grounded or attached to the spark plug.


#17

V

VegetiveSteam

Peva said:
FYI - You should avoid firing an ignition (whether lawnmower or automotive) without a path to ground either through the specified spark plug gap or direct short to ground.

Here's why: The ignition coil can generate much higher voltage than it takes to fire the properly gapped spark plug. When the spark plug fires, the resistance of the ionized air in the spark plug gap is so low that the coil output voltage can't rise above the voltage that it took to ionize the air in the gap to initiate the spark. When the coil output wire is held out in the air, far from a ground, the voltage rises tens of thousands of volts higher than the spark plug gap allows. The insulation inside the coil cannot withstand that high of a voltage and will arc through the insulation of the coil - which blows a pin hole through the insulation, leaving carbonized (conductive) material coating the inside of that hole - so the coil is now defective - no longer allows the coil output voltage to rise to the ionization voltage of the proper spark plug gap.
Click to expand...
Folks will argue that they do it all the time and never had one fail but what they don't realize is, while it may not immediately fail, they have almost certainly just shortened the life of that coil significantly. So now a coil that really should have lasted the life of the engine fails prematurely.


#18

G

Gym123

If you really want a good test for spark, use a spark plug or a spark gap tester.


#19

M

MParr

StarTech said:
it because it got one these stupid plug wire terminals.
View attachment 68893
They tend to break the high tension (plug wire) lead internal conductor then make contact sometimes and other times they don't.

Usually you can snip off the section where the hole is and reinstall the terminal.
Click to expand...
Yep! Try not to lose that terminal.


#20

woodstover

woodstover

Joed756 said:
Without supplying the make, model, and serial number you make it much more difficult for us to troubleshoot.
Click to expand...
😂🤣😂


#21

P

Peva

Gym123 said:
If you really want a good test for spark, use a spark plug or a spark gap tester.
Click to expand...
Or fire the ignition while peeing on the wire. If the ignition is working, it will be immediately obvious. 🤷‍♂️ 🙀


#22

StarTech

StarTech

Peva said:
Or fire the ignition while peeing on the wire. If the ignition is working, it will be immediately obvious. 🤷‍♂️ 🙀
Click to expand...
OH I had a dog to test my electric once. He spent the next three hours howling everytime he moved. Nearly disable his hindquarters.


#23

woodstover

woodstover

StarTech said:
OH I had a dog to test my electric once. He spent the next three hours howling everytime he moved. Nearly disable his hindquarters.
Click to expand...
😨


#24

I

ILENGINE

About 40 years ago had an old Wisconsin 7 hp engine that had been transplanted onto a Wheel Horse. This was one of old ones with the magneto style engine. Which meant that you could turn the flywheel slowly by hand and it would click. That click was a full power discharge to the spark plug.

My older brother got the brilliant idea to hang onto the spark plug wire while I cranked the engine over slowly. That thing got him 6 or 7 times before he could let go of the spark plug wire.


#25

G

Gym123

Peva said:
Or fire the ignition while peeing on the wire. If the ignition is working, it will be immediately obvious. 🤷‍♂️ 🙀
Click to expand...

I gabbed the wires of an electric fence one. Just once. That was just about enough, for me......I also put my hand on a distributor cap AND exhaust manifold when I was working on a boat with 5.7L Chevy engine. That.Was.No.Fun.At.All.



#26

S

slomo

One reason why I don't use the Christmas light style spark tester. I want to see spark hop a 1/4"+ gap in free air. PET-4000 can't be beat for testing spark.

Seen several coils have weak to minimal spark. Most I can polish the coil and block mounting pads up to restore the ground. Mounting screws get rusty too. Nice blue spark again.


#27

Hammermechanicman

Hammermechanicman

I have both a couple different gap type testers and a couple of the inline neon type. They are actually used differently and they tell you differet things.


#28

G

Gym123

slomo said:
One reason why I don't use the Christmas light style spark tester. I want to see spark hop a 1/4"+ gap in free air. PET-4000 can't be beat for testing spark.

Seen several coils have weak to minimal spark. Most I can polish the coil and block mounting pads up to restore the ground. Mounting screws get rusty too. Nice blue spark again.
Click to expand...
It's a bit ironic that so many spark gap testers are open-air, since they're often used when combustible fumes are present.


#29

A

Auto Doc's

The plug wire terminal end is worn and making poor contact. This can get confusing due to the intermittent operation. Option one is change the terminal end to a crimp style one if you have enough lead to do that. Option two is to dismantle the machine and replace the coil.


#30

M

mikekir

Different motors have different coils. Mercury outboards have voltage five times other motors. Getting caught by one will bring you to your knees.


#31

StarTech

StarTech

mikekir said:
Different motors have different coils. Mercury outboards have voltage five times other motors. Getting caught by one will bring you to your knees.
Click to expand...
Sounds like getting by those 27" CRT that I forgot to discharge before touching. 40KV hurts.


#32

Hammermechanicman

Hammermechanicman

The flash lamp power supply in the xerox machine like in the movie 9 to 5 has 4 capacitors that are measured in farads. Not microfarads. Fed by 50 amp 240v. A service rep did a dumbass and got a hand across it and it fires at 3 times a second. He retired with disability because he destroyed the nerves in his hand. the capacitirs are 6 inches in diameter and 18 inches tall with 1/2" lugs for connection. Fires an arc through 4 one foot long xenon flash tubes.
Danger Will Robinson!


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