Stuart
New member
Hi, I have replaced the coil, leads, plug and flywheel on my Stihl 391, still no spark....any ideas anyone ?
Stuart
Stuart
No Spark
- Thread starter Stuart
- Start date
Bryan Newton
New member
When you say leads do you mean the kill switch wires
Stump Shot
Active member
Try starting(checking for spark) the saw with the shorting(kill) wire disconnected from the coil at the coil. If you have spark then either the wire or the switch are defective, then disconnect at switch to find out which.
Stuart
New member
Thanks for your response,
Yes, I replaced the kill wires and the plug wire (complete with the new coil). Have disconnected the kill wires…still no spark. Just can’t figure it out….bizarre…am at a loss….BTW I bought 2 new coils to ensure the first replacement was not faulty.
Stuart
Yes, I replaced the kill wires and the plug wire (complete with the new coil). Have disconnected the kill wires…still no spark. Just can’t figure it out….bizarre…am at a loss….BTW I bought 2 new coils to ensure the first replacement was not faulty.
Stuart
Can you explain how you are "testing" for spark?
I find it easier on Stihl saws to find a length of insulated multi core wire and bare both ends- wrap one end under the crush washer of the spark plug and make a loop in the other bared end to fit under something like a bucking spike bolt- this ensures a good earth to the plug on the saw body and both hands can be used to hold the saw and pull the starter handle with some force- as some modules require a fast spin to create spark.
How did we arrive at the conclusion the saw needed new coils, new wires, new flywheel? Did it come to you needing all this, or did something go wrong during use and this has been your process of elimination?
I find it easier on Stihl saws to find a length of insulated multi core wire and bare both ends- wrap one end under the crush washer of the spark plug and make a loop in the other bared end to fit under something like a bucking spike bolt- this ensures a good earth to the plug on the saw body and both hands can be used to hold the saw and pull the starter handle with some force- as some modules require a fast spin to create spark.
How did we arrive at the conclusion the saw needed new coils, new wires, new flywheel? Did it come to you needing all this, or did something go wrong during use and this has been your process of elimination?
Stuart
New member
My word Bob…..Many thanks for your response.
Essentially, I disconnected both wires at the coil and checked for spark. The reason I find myself in this difficult position, is that I rebuilt the engine as unfortunately one of my kids caused it to die. The same happened to my Stihl 310, which I recently also rebuilt with no problem.
When I came to start the 391….no spark. Tested the coil with my multi meter, the result was inconclusive, so I bought a replacement, with no result. As it was from a far eastern location, I questioned the quality and bought a second…same result. Replaced the flywheel as there was nowhere else to go…same result. Chances are I have 3 perfectly good coils and 2 flywheels…
and I feel you are correct, I’m doing something, obvious, wrong, and struggling cause I aint no expert. I like your suggestion of the multicore wire scenario and will give it a shot tomorrow (I’m located in Australia) and let you know the result….If you can think of anything else (having received my response) that I may be doing wrong….would appreciate if you could let me know.
Many Thanks………Stuart
Essentially, I disconnected both wires at the coil and checked for spark. The reason I find myself in this difficult position, is that I rebuilt the engine as unfortunately one of my kids caused it to die. The same happened to my Stihl 310, which I recently also rebuilt with no problem.
When I came to start the 391….no spark. Tested the coil with my multi meter, the result was inconclusive, so I bought a replacement, with no result. As it was from a far eastern location, I questioned the quality and bought a second…same result. Replaced the flywheel as there was nowhere else to go…same result. Chances are I have 3 perfectly good coils and 2 flywheels…
and I feel you are correct, I’m doing something, obvious, wrong, and struggling cause I aint no expert. I like your suggestion of the multicore wire scenario and will give it a shot tomorrow (I’m located in Australia) and let you know the result….If you can think of anything else (having received my response) that I may be doing wrong….would appreciate if you could let me know.Many Thanks………Stuart
Stuart
New member
Ha’ Ha’…..Sorry Bob….bit slow…again…Got Yer…NZ….yes wrong side…..and I’m a Pommy B !
Stuart
New member
Oh' Dear.....New to this...now I'm questioning if you got all of my response....below...
My word Bob…..Many thanks for your response.
Essentially, I disconnected both wires at the coil and checked for spark. The reason I find myself in this difficult position, is that I rebuilt the engine as unfortunately one of my kids caused it to die. The same happened to my Stihl 310, which I recently also rebuilt with no problem.
When I came to start the 391….no spark. Tested the coil with my multi meter, the result was inconclusive, so I bought a replacement, with no result. As it was from a far eastern location, I questioned the quality and bought a second…same result. Replaced the flywheel as there was nowhere else to go…same result. Chances are I have 3 perfectly good coils and 2 flywheels… and I feel you are correct, I’m doing something, obvious, wrong, and struggling cause I aint no expert. I like your suggestion of the multicore wire scenario and will give it a shot tomorrow (I’m located in Australia) and let you know the result….If you can think of anything else (having received my response) that I may be doing wrong….would appreciate if you could let me know.
Many Thanks………Stuart
My word Bob…..Many thanks for your response.
Essentially, I disconnected both wires at the coil and checked for spark. The reason I find myself in this difficult position, is that I rebuilt the engine as unfortunately one of my kids caused it to die. The same happened to my Stihl 310, which I recently also rebuilt with no problem.
When I came to start the 391….no spark. Tested the coil with my multi meter, the result was inconclusive, so I bought a replacement, with no result. As it was from a far eastern location, I questioned the quality and bought a second…same result. Replaced the flywheel as there was nowhere else to go…same result. Chances are I have 3 perfectly good coils and 2 flywheels…
and I feel you are correct, I’m doing something, obvious, wrong, and struggling cause I aint no expert. I like your suggestion of the multicore wire scenario and will give it a shot tomorrow (I’m located in Australia) and let you know the result….If you can think of anything else (having received my response) that I may be doing wrong….would appreciate if you could let me know.Many Thanks………Stuart
Stump Shot
Active member
Okay, if we start here- disconnected "both" wires at the coil? Any chance of a photo with these two wires connected?
I am guessing (without IPL checking) one of those wires grounds the coil body and the other runs to the kill switch- the first must remain connected to allow the coil to work.
Exactly what did the kid do that caused the saw to die?
My guess is- disassembly and subsequent rebuild do not match the original spec pre break down- something is not like it used to be and not allowing circuits to complete.
I would be going back to original Stihl flywheel and coil and starting again there- have no faith in the elcheapo replacement parts.
Oh' Dear.....New to this...now I'm questioning if you got all of my response....below...
My word Bob…..Many thanks for your response.
Essentially, I disconnected both wires at the coil and checked for spark. The reason I find myself in this difficult position, is that I rebuilt the engine as unfortunately one of my kids caused it to die. The same happened to my Stihl 310, which I recently also rebuilt with no problem.
When I came to start the 391….no spark. Tested the coil with my multi meter, the result was inconclusive, so I bought a replacement, with no result. As it was from a far eastern location, I questioned the quality and bought a second…same result. Replaced the flywheel as there was nowhere else to go…same result. Chances are I have 3 perfectly good coils and 2 flywheels…
Many Thanks………Stuart
Stuart- can you tell me which type of air filter you have on your 391?
Earlier ones had a kind of pentagonal cube arrangement and the later ones the cylindrical twist on ones.
Stuart
New member
Hi Bob,
Fotee Attached.
I didn’t do your multicore wire piece, as my son turned up and he was able to pull the cord vigorously whilst I held the spark plug against the cylinder…..No Spark…..I used original components plus replacements….same result.
Guess you can see the twist on round air filter.
My sons scored the pistons and cylinders on both the 310 / 391 units, I was overseas at the time, I’m guessing wrong fuel mixture/heat?
Cheers…..Stuart
Fotee Attached.
I didn’t do your multicore wire piece, as my son turned up and he was able to pull the cord vigorously whilst I held the spark plug against the cylinder…..No Spark…..I used original components plus replacements….same result.
Guess you can see the twist on round air filter.
My sons scored the pistons and cylinders on both the 310 / 391 units, I was overseas at the time, I’m guessing wrong fuel mixture/heat?
Cheers…..Stuart
Attachments
Stuart
New member
Thanks Stump Shot, Don't know if we exactly got the 850RPM....but I'm guessing somewhere close....
Cheers....Stuart
Okay, because there are not only two different air filters, but they are the indicator for two different coils- ones part number ends in 4, the newer one for the round filter should end in 7.
But if all components are back to original, then we can guess they should all be matched- so, get your son to hold the plug in his mouth while you pull the rope fast as you can- that will confirm/deny if you have spark.
Silly question- but the kill switch is set to run or choke with that black wire attached and still no spark?
Stuart
New member
Hi Bob,
Tried with leads connected and in run and choke mode….No Spark.
The original coil ID: 1140 1305 B MC3 1140F UA312 Y. Made in Germany.
The first replacement ID: Zero
The second replacement Bought from Jono & Johno ID: XY36E 20210411
Cheers……Stuart
Tried with leads connected and in run and choke mode….No Spark.
The original coil ID: 1140 1305 B MC3 1140F UA312 Y. Made in Germany.
The first replacement ID: Zero
The second replacement Bought from Jono & Johno ID: XY36E 20210411
Cheers……Stuart
Okay, before the boy killed it- it ran perfect eh? I mean it had spark and ran like normal before he filled it up with straight petrol?
You came home to discover two broken saws, did not beat him around the head with either, but rebuilt them- one runs fine and the other now has no spark?
What I am getting at, is how do we go from a running saw having fried to top end, torn down and put back together suddenly suffering an electrical issue?
Or did this 391 run for a while after rebuild, then develop the no spark issue?
Would not trust the Jono & Johno part numbers as meaning anything- they import and sell at inflated prices cheap Asian knock off parts that can be made anywhere in the big red flagged country with no quality control and they are free to mark them any way they want.
You came home to discover two broken saws, did not beat him around the head with either, but rebuilt them- one runs fine and the other now has no spark?
What I am getting at, is how do we go from a running saw having fried to top end, torn down and put back together suddenly suffering an electrical issue?
Or did this 391 run for a while after rebuild, then develop the no spark issue?
Would not trust the Jono & Johno part numbers as meaning anything- they import and sell at inflated prices cheap Asian knock off parts that can be made anywhere in the big red flagged country with no quality control and they are free to mark them any way they want.
Back to the simple side- top of the spark plug- what do you see? Bare threads about 1/8" in diameter, or an aluminium looking hour glass?
If you look into the boot that covers the top of the spark plug at the end of the high tension lead- what do you see?
Even better, if you wriggle that boot off the HT lead, what is in there?
When you rebuilt and fitted the coil- how did you control the air gap between coil and flywheel?
If you look into the boot that covers the top of the spark plug at the end of the high tension lead- what do you see?
Even better, if you wriggle that boot off the HT lead, what is in there?
When you rebuilt and fitted the coil- how did you control the air gap between coil and flywheel?
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Stuart
New member
Hi Bob,
The 391 unit has not run since I rebuilt the engine, due to no spark. Have been using a new park plug (which came with the engine bits) which I know is good cause I checked it out with the 310 unit. I controlled the air gap between the magnet/coil with a business card or 0.25mm with feeler gauges. Solid connection between HT lead and spark plug on all 3 coils.
I’m now sitting with the 3 coils and my multimeter and the only one I’m getting ohms readings on both the primary and secondary sides is the original…. And even that is a wee bit touch and go !!
So, to be honest I’m back on the coil scenario, although it does seem unlikely/exasperating that all 3 coils are iffy.
What do you think ?
Cheers…..Stuart
The 391 unit has not run since I rebuilt the engine, due to no spark. Have been using a new park plug (which came with the engine bits) which I know is good cause I checked it out with the 310 unit. I controlled the air gap between the magnet/coil with a business card or 0.25mm with feeler gauges. Solid connection between HT lead and spark plug on all 3 coils.
I’m now sitting with the 3 coils and my multimeter and the only one I’m getting ohms readings on both the primary and secondary sides is the original…. And even that is a wee bit touch and go !!
So, to be honest I’m back on the coil scenario, although it does seem unlikely/exasperating that all 3 coils are iffy.
What do you think ?
Cheers…..Stuart
What do I think?
Well it was working before the rebuild- not working after- so in my mind has to be something simple like a broken HT line as it is about the only thing we have not covered- but on all 3 coils?
Seems highly unlikely all 3 coils are iffy.
Shame the other saw is a 310 and not a 311......
If you swap out coils, flywheels and kill/earth wires- what has been the one commonality? Have you been using the same plug each time?
The wire with the two eye terminals, the one that slips over the bolt of the coil- the other end is correctly fitted to the manifold bracket and earthing to the cylinder eh?
Well it was working before the rebuild- not working after- so in my mind has to be something simple like a broken HT line as it is about the only thing we have not covered- but on all 3 coils?
Seems highly unlikely all 3 coils are iffy.
Shame the other saw is a 310 and not a 311......
If you swap out coils, flywheels and kill/earth wires- what has been the one commonality? Have you been using the same plug each time?
The wire with the two eye terminals, the one that slips over the bolt of the coil- the other end is correctly fitted to the manifold bracket and earthing to the cylinder eh?