Good way for one man to check spark while pulling cord?

[Joseph Acquisto]

When working alone, what's a good, reliable, way to check for spark? I have an Stihl 029 that I did get running after a long sit, and cut with maybe half a day.

Now, it won't start. Fuel is fresh, new NGK plug. Squirting fuel in the carb does not help, so I suspect a bad igniter or coil, which may be one unit on this one.

Still, it's money and work wasted if that's not it.

 

[lone wolf]

When working alone, what's a good, reliable, way to check for spark? I have an Stihl 029 that I did get running after a long sit, and cut with maybe half a day.

Now, it won't start. Fuel is fresh, new NGK plug. Squirting fuel in the carb does not help, so I suspect a bad igniter or coil, which may be one unit on this one.

Still, it's money and work wasted if that's not it.

Pull the plug ,leave wire on and let it ground the plug on the cylinder do in a dark area pull it over and look.

 

[Wood Doctor]

Pull the plug ,leave wire on and let it ground the plug on the cylinder do in a dark area pull it over and look.

That's normally how I do it, but now and then you need a jumper wire between the plug and the cylinder or even the muffler in order to ground it out. I usually connect an aligator clip to one end of the ground wire.

 

[MnSam]

I grasp the plug in my fist and ground to the cylinder with my pinkie. Not the most technical but I've gotten good at telling if the spark is good based on the pain inflicted.

 

[ballisticdoughnut]

One thing to check is the kill switch wire. If it’s rubbed through and grounding out that will kill the spark even if the switch is in the on position.

 

[pdqdl]

$11.24 at Walmart.

There are versions that light up, too.

 

[Philbert]

now and then you need a jumper wire between the plug and the cylinder or even the muffler in order to ground it out.

I made a short jumper wire with alligator clips at both ends: one for the ground electrode and one for a cylinder fin. This lets me see the exact plug spark.

Philbert

 

[pdqdl]

Any spark testing method that uses the spark plug isn't the best system. Your test should bypass any plug (which might be defective). It should also include the correct air gap to properly detect whether there is enough voltage to do the job. Watching a spark on the plug only confirms when it is all working. It doesn't tell you what is wrong when it isn't sparking.

 

[Chevboy0167]

This has been working good for me...

https://www.ebay.com/itm/204014457105?epid=1911826530&hash=item2f80359111:g:tGAAAOSwirpiugAC

 

[TRTermite]

I grasp the plug in my fist and ground to the cylinder with my pinkie. Not the most technical but I've gotten good at telling if the spark is good based on the pain inflicted.

100% on your method. I have a friend that will NOT do this even if he is pulling the starter rope. Cheap Entertainment.

 

[Del_]

The coils on some motors count on the spark plug gap for loading the coil so peak voltage is limited. Some coils when not loaded may exceed peak voltage ratings and destroy insulation inside of the coil.

I bet a lot of coils get damaged that way.

To me it defies my intuition but some coils are better shorted to ground than they are to be run unloaded. Talking multi cylinder engines of course.

 

[Philbert]

Any spark testing method that uses the spark plug isn't the best system. Your test should bypass any plug (which might be defective). It should also include the correct air gap to properly detect whether their is enough voltage to do the job. Watching a spark on the plug only confirms when it is all working. It doesn't tell you what is wrong when it isn't sparking.

It’s a first step for me: fuel, air, spark, compression. Not a final diagnosis

Philbert

 

[Old2stroke]

The coils on some motors count on the spark plug gap for loading the coil so peak voltage is limited. Some coils when not loaded may exceed peak voltage ratings and destroy insulation inside of the coil.

I bet a lot of coils get damaged that way.

To me it defies my intuition but some coils are better shorted to ground than they are to be run unloaded. Talking multi cylinder engines of course.

YES!! I have been trying to convince people for years that they should not be pulling an engine over fast with the ignition on and no path to ground for the spark energy to go. With a plug connected, the spark voltage will normally not rise above about 20kv but with no path to ground it will rise to the maximum the coil can produce and that can be enough to start breaking down the thin enamel insulation on the secondary windings, eventually leading to carbon trace paths and a dead coil. Shorting the plug lead to ground will NOT damage the coil,

 

[Captain Bruce]

When working alone, what's a good, reliable, way to check for spark? I have an Stihl 029 that I did get running after a long sit, and cut with maybe half a day.

Now, it won't start. Fuel is fresh, new NGK plug. Squirting fuel in the carb does not help, so I suspect a bad igniter or coil, which may be one unit on this one.

Still, it's money and work wasted if that's not it.

Reliable way? Its a 5 buck spark tester,,,,,,,,,,

 

[Joseph Acquisto]

Interesting ideas. I tried the spark testers from HF long ago, which sorta work, but the light is pretty dim and hard to see at arms length when pulling against compression.

I settled on pulling the plug, leaving it in the plug boot and grounding it with a large alligator clip to the cylinder fins. No spark. Checked for a good ground with meter as well. Got an empty TP roll and stuck it around the plug for a better view. Still no spark.

Before I order a new coil/igniter I may get some cotton wadding, or just paper towel dampen it with fuel, stuff it in the tube, or maybe just around the plug and then give it a pull. If there is any spark at all, it should be pretty obvious in just an instant.

What, me worry?

 

[Philbert]

Just a word of caution here. Will be obvious to some, but might be a helpful reminder for others.

Gasoline is explosively flammable.

Several years back a member posted about his brother getting seriously burned when testing for spark on a flooded saw. There was spark. And there were fuel vapors.

We get pretty complacent about fuel, but sometimes the conditions are just right. . .

Easy to be obsessed with a problem saw and forget about some fuel spilled on a shirt, some jeans, on a work table, etc.

Using a jumper wire lets you stuff a rag in the cylinder hole, and clip into a ground point a few inches away.

Philbert

 

[pdqdl]

I spent a week in a burn unit when I was diagnosing a v-8 engine with a percieved cylinder block by a suspected coolant leak into the cylinder. It turns out my mechanic had wired the electric fuel pump hot all the time, so gasoline trickled down from the carb and filled a couple of cylinders. So... I pulled all the spark plugs and told an assistant to crank the engine over while I watched which cylinder was filled with water.

Well! That didn't turn out right. The engine sprayed me with gasoline coming out the open spark plug holes and then lit it on fire with a spark. Needless to say, I wasn't amused at that turn of events.

Yeah, I don't recommend charging a piston cylinder with gas and using that method as a spark tester, either.
On a purely technical point, most all the spark checkers also isolate the spark from the possibly gasoline impregnated air, so they won't start any blazes on you, either.

 

[hotajax]

If my wife's been nagging me all week, I have her hold the spark plug against the block with two hands. While she's standing in a puddle.

 

[GenXer]

Take a brand new plug put it in the socket and touch it against the existing plug, spark will show and engine will start/run safely without problem

 

[Billhook]

https://www.amazon.co.uk/Accuspark-...ster&sprefix=soark+plug+tester,aps,138&sr=8-4