272Xp ignition problem

[Sparky_NY]

First a bit of history... saw was running fine then shut off while idling. I checked and it was low on gas so I filled and tried to restart. No go, so I assumed I flooded it and grabed another saw. When I got it home I checked it out further and found no spark.

So, no spark. I disconnect the kill switch wire, still no spark. Tried a new plug, no spark. Tried adding a jumper wire to make sure plug had good ground while testing on top of cylinder, nope, no go.

Got another coil, used but supposed to be tested and to my suprise still no go. Same symptoms.

The coil was gapped with a business card, kill switch wire left off, flywheel magnets strong and both intact.

Any other possibilities other than a bad coil?

 

[PES+]

Give that coil you are trying a few really good full pulls to make sure it is not working then try another coil.

Make sure you have a good ground connection between the coil and the saw case metal and make sure the ground lead (if there is one on the coil) is not broken under the insulation and that it is making good ground contact as well.

A business card is a little thick....use an old car insurance card...they are thinner and plastic coated

 

[Sparky_NY]

Give that coil you are trying a few really good full pulls to make sure it is not working then try another coil.

Make sure you have a good ground connection between the coil and the saw case metal and make sure the ground lead (if there is one on the coil) is not broken under the insulation and that it is making good ground contact as well.

A business card is a little thick....use an old car insurance card...they are thinner and plastic coated

I only have the original coil and the used/tested replacement one, no others.

Original coil had the green ground wire, the replacement did not, otherwise identical. I used a clip lead supplemental ground to the coil frame and the spark plug threads, grounding both to the cylinder just to ensure good grounds.

All my searching only found a business card as the correct gap, never a mention of a actual measurement in thousanths or I would have done that. I will try closing the gap up smaller just for kicks and see if that brings it to life.

Out of curiosity, what difference would plastic coating make on the card used for gapping being its removed anyways?

 

[Freakingstang]

On some saws the regular business car is thicker than it should be. All pest was trying to say was use a thinner card. The plastic coating just makes it easier to use and holds up better after repeated use.

 

[PES+]

Makes it easier to get it out so you can set it tighter

 

[Sparky_NY]

I don't know how critical the gap is. As mentioned, I searched here but never found a actual spec. for the gap, only a "business card" . Is there a actual spec? Using a card with no defined thickness seems to be sort of hit or miss? I have feeler gauges and micrometers and can set it to the required spec if that is known.

Update: I have tried it at .014 .009 and .004 gaps, none produce a spark. Supplemental grounding clipleads to ensure good ground at the coil and the plug. Plug at .020. Lights out during test and not a hint of spark. Wire to kill switch left off.

Any thing other than a bad coil? (original and "tested" replacement)

 

[parrisw]

Air gap factory spec is .012, I just used some paper folded up until it measured 12thou. And On my 272xp, I tried a coil like that that you tried, and it didn't work, I had the same problem. I got a coil with the external ground lead, and it then worked fine.

 

[trimmmed]

spec

.012 in.

 

[Sparky_NY]

Air gap factory spec is .012, I just used some paper folded up until it measured 12thou. And On my 272xp, I tried a coil like that that you tried, and it didn't work, I had the same problem. I got a coil with the external ground lead, and it then worked fine.

I was afraid of that. They are supposed to be interchangeable between about 6 models but my original had the green ground wire and the replacement does not. I assumed they just put the ground connection internally. I am still in disbelief, I expected the thing to fire right up.

 

[parrisw]

Ya, Im not totally sure on how it grounds, I guess just internally through the mounting bolt. I was a little suprised as well, when I still had no spark, I ended up getting a used coil and all it good now.

 

[PES+]

Look closely at the laminations and you will see a tab that comes out of the coil and is spot welded to the laminations somewhere

 

[Sparky_NY]

Look closely at the laminations and you will see a tab that comes out of the coil and is spot welded to the laminations somewhere

Thats what I figured. So what do you think? Should the 2 types interchange? These ignitions are so simple there isn't much to go wrong besides the coil and the kill switch/wire it would seem. (not counting flywheel key shearing but that would still give spark, just the wrong time)

 

[PES+]

I have no way of telling without seeing the modules.

Can you post some pics?

 

[Sparky_NY]

I have no way of telling without seeing the modules.

Can you post some pics?

No camera available unfortunately. They look identical except for the green ground wire.

I am going with the bad coil answer for lack of any other cause for now.

 

[AZLOGGER]

Thats what I figured. So what do you think? Should the 2 types interchange? These ignitions are so simple there isn't much to go wrong besides the coil and the kill switch/wire it would seem. (not counting flywheel key shearing but that would still give spark, just the wrong time)

Sparky, The ignitions are a little more complex than they appear, last year at the service school they had 2 ignitions that were done in clear coverings. There are a bunch of diodes, resistors,and etc built into them. Also as a warning to all that read this thread, some of the new ignitions coming on outdoor power equipment are to be used with resistor sparkplugs only, if you use a non resistor sparkplug it will kill the ignition module. So be sure and read your owners manual, because if you use the wrong sparkplug there will be no warranty on a failed ignition, and yes we can check to see if that is the cause of the failure.
"Don't say you weren't warned".

:jawdrop:

 

[PES+]

Sweet #$%......they FINALLY listened to us......

10 years ......they are improving ROTF

 

[parrisw]

Sparky, The ignitions are a little more complex than they appear, last year at the service school they had 2 ignitions that were done in clear coverings. There are a bunch of diodes, resistors,and etc built into them. Also as a warning to all that read this thread, some of the new ignitions coming on outdoor power equipment are to be used with resistor sparkplugs only, if you use a non resistor sparkplug it will kill the ignition module. So be sure and read your owners manual, because if you use the wrong sparkplug there will be no warranty on a failed ignition, and yes we can check to see if that is the cause of the failure.
"Don't say you weren't warned".

:jawdrop:

How can you check to see if a resisted or non resisted plug was used??

 

[AZLOGGER]

How can you check to see if a resisted or non resisted plug was used??

"If I told you I'd have to kill you!"

No all kidding aside there is a test using a multimeter, to check out the ignition modules and the numbers will be higher or lower depending on the test. I don't remember the exact figures, but I have them somewhere in my notes from service school. I'll have to dig them out to refresh my memory, (old timers disease).

 

[parrisw]

"If I told you I'd have to kill you!"

No all kidding aside there is a test using a multimeter, to check out the ignition modules and the numbers will be higher or lower depending on the test. I don't remember the exact figures, but I have them somewhere in my notes from service school. I'll have to dig them out to refresh my memory, (old timers disease).

Hmm, I just find it kinda hard to believe from a simple resistance test that one could tell how a ignition module was blown?? Not trying to create a argument here, so don't take any offence here. Just curious how this is possible???

 

[Grande Dog]

If you're checking your spark against the cylinder, make sure the cylinder has continuity to the module. It could also be a bad replacement part. It's not likely but, possible.