What is special about Stihl ZAT 4 ignition tester? Chainsaw problem

[miket1]

Long story short, saw quit running. Checked spark, no spark. Replaced plug, no spark. Removed kill switch wire, no spark. Went to authorized Stihl dealer and he said Stihl coils dont go bad, its not the coil. Was quite rude about it. He said it must be checked using a ZAT 4 tester. I bought a regular in line tester, no spark. ( despite never needing one in my life, have always been able to see a spark )

What is special about the ZAT 4? Will a regular in line tester work? Why is he saying you cant check it the regular way? I have seen the spark before on this saw when a plug went bad and I replaced it. He says that will not work with these saws. None of what he says makes any sense.

He has been doing it for 30yrs, so Im really trying to listen to him based on experience, but seriously questioning the logic to it all

 

[85Hokie]

Im guessing here - probable has a computer chip in it to sense the electrical pulse.

Cost is a bit too - over $50

 

[MOOTS]

Long story short, saw quit running. Checked spark, no spark. Replaced plug, no spark. Removed kill switch wire, no spark. Went to authorized Stihl dealer and he said Stihl coils dont go bad, its not the coil. Was quite rude about it. He said it must be checked using a ZAT 4 tester. I bought a regular in line tester, no spark. ( despite never needing one in my life, have always been able to see a spark )

What is special about the ZAT 4? Will a regular in line tester work? Why is he saying you cant check it the regular way? I have seen the spark before on this saw when a plug went bad and I replaced it. He says that will not work with these saws. None of what he says makes any sense.

He has been doing it for 30yrs, so Im really trying to listen to him based on experience, but seriously questioning the logic to it all

What saw?

 

[miket1]

What saw?

Stihl MS271 I think I bought it around 2010 or 12

I do remember at some point the plug went bad and I replaced it and the regular test ( holding it against the head ) showed a spark with the new plug. The mechanic says that doesnt work because the head is aluminum magnesium. Last I checked AL was conductive.....

 

[MOOTS]

Stihl MS271 I think I bought it around 2010 or 12

I do remember at some point the plug went bad and I replaced it and the regular test ( holding it against the head ) showed a spark with the new plug. The mechanic says that doesnt work because the head is aluminum magnesium. Last I checked AL was conductive.....

Any old inline tester will work. Coils do go bad, even Stihls. You can ohm test them to see if they are working, would have to google how. I don’t remember off the top of my head. It’s pretty simple.

Also, check continuity from coil to plug cap. I’ve had the cap that snaps on plug come out of the wire. Easy fix.

 

[fried1765]

Stihl MS271 I think I bought it around 2010 or 12

I do remember at some point the plug went bad and I replaced it and the regular test ( holding it against the head ) showed a spark with the new plug. The mechanic says that doesnt work because the head is aluminum magnesium. Last I checked AL was conductive.....

No!
Aluminum must not be conductive enough!
Remember all the aluminum housing wire that had to be replaced?
I know,.... using the proper flux is acceptable with large size AL wire, but it is long gone for the household 15A or 20A circuits.

 

[miket1]

No!
Aluminum must not be conductive enough!
Remember all the aluminum housing wire that had to be replaced?
I know,.... using the proper flux is acceptable with large size AL wire, but it is long gone for the household 15A or 20A circuits.

Just to make sure Im not crazy, I just checked continuity between the head and the flywheel, magically there is zero resistance between the two haha

I did want to be a smart a and ask him what he thought the spark plug screwed into, but I kept my mouth shut....

 

[85Hokie]

No!
Aluminum must not be conductive enough!
Remember all the aluminum housing wire that had to be replaced?
I know,.... using the proper flux is acceptable with large size AL wire, but it is long gone for the household 15A or 20A circuits.

The reason why back in the day - Alum would expand and contract a little too good when the electrons would flow, heating the wire up a bit. That expansion and contraction would cause it to become loose on the screw - and now we have a bit of arcing inside the walls of the house!

Plus - Aluminum conducts about 60% of what copper does.

 

[fried1765]

The reason why back in the day - Alum would expand and contract a little too good when the electrons would flow, heating the wire up a bit. That expansion and contraction would cause it to become loose on the screw - and now we have a bit of arcing inside the walls of the house!

Plus - Aluminum conducts about 60% of what copper does.

Oh, I understood!
I was just playing with the tongue -in- cheek possibility of the non conductivity of aluminum, suggested by the responder.

 

[bird dogger]

[QUOTE="miket1, post: 719688, member: 62527"

I did want to be a smart a and ask him what he thought the spark plug screwed into, but I kept my mouth shut....
[/QUOTE]
Exactly what I was thinking as I read your post. Too bad you didn't ask!! We all would've loved to hear his answer to that question!!

 

[Fordtech86]

Don’t need no tester, just have some one else hold the plug while you pull the rope

 

[85Hokie]

Don’t need no tester, just have some one else hold the plug while you pull the rope

You aint gonna believe this ..........

circa 1984 - I am "student teaching" at a middle school, the topic of the month was small engines, so students brought a few 3.5 and 5 hp engines in....

the topic of HOW the spark happens come up, and I am "trying" to teach induction via magnetism - now remember, these are 7th and 8th graders. I try to explain how the magnet comes by the coil and then voltage is increased ....blah blah blah..

They could not get it - so I asked for a volunteer - The "bully" of the class stepped up, I told him to hold the lead, I turned the flywheel by hand, about one time - a small little blip - I did ask him, did you feel the jolt of electrons?

He looked at me and said " SPIN IT AGAIN FASTER!" and so I did !

TODAY they would place me under the jail!

 

[JRHill]

Duplicate, oops

 

[torch]

Spark under compression requires higher voltage than spark in free air. So it is possible to have a false positive when checking for spark by taking the plug out.

Testers that check for current with the plug installed under compression are less prone to false positives. I believe the Stihl ignition module tester falls into this category. The mechanic may have been taught to only use the Stihl tester for this reason.

All that said, if it won't even spark in free air, there's definitely a problem. No such thing as a false negative here.

 

[lynnmor]

Spark under compression requires higher voltage than spark in free air. So it is possible to have a false positive when checking for spark by taking the plug out.

I keep some old plugs to use for testing. I gap them at double the specification to allow for the no compression.

 

[miket1]

Well, I took the saw to the authorized dealer today and asked him to check it with his superduper ZAT 4 tester. He hooked it up and gave it a yank and almost before it turned over he said "its got fire". I didnt see it and said, "dang I didnt even see it" as nice as I could, so he turned off the lights and yanked it and there was no spark. Yanked a couple more times and said " coil is bad" all matter of factly, like he had discovered I hadnt repeatedly told him.

His entire demeanor changed when it didnt spark. Turned into the nicest guy you ever met. Offered to change it out for free, I accepted. He put it on and back together and it cranked right up.

 

[fried1765]

Well, I took the saw to the authorized dealer today and asked him to check it with his superduper ZAT 4 tester. He hooked it up and gave it a yank and almost before it turned over he said "its got fire". I didnt see it and said, "dang I didnt even see it" as nice as I could, so he turned off the lights and yanked it and there was no spark. Yanked a couple more times and said " coil is bad" all matter of factly, like he had discovered I hadnt repeatedly told him.

His entire demeanor changed when it didnt spark. Turned into the nicest guy you ever met. Offered to change it out for free, I accepted. He put it on and back together and it cranked right up.

Weird guy,......but you did get it fixed,.... and for free!

 

[MOOTS]

Weird guy,......but you did get it fixed,.... and for free!

I’m betting the labor for install was free, coil not so much. Maybe I’m wrong?

 

[Fordtech86]

I love it when the customer is right

 

[Vlach7]

A Stihl coil never goes bad? Changed out my neighbors 6 months ago.