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Stihl 090 electronic IGN No Spark

#1

skippymud

skippymud

Hello All

Stihl 090
Actual age unknown
Guessing 1978

First, I feel not so smart right now. Today is the day I can't diagnose the cause behind no spark on an electronic ignition setup

Coil tests good at 7 Ohms
Kill switch is disconnected
New ignition module
New Ignition mounting plate. The previous plate was the wrong one for this saw, or was cheaply made and therefore did not offer the correct clearance
There is perfect continuity through the spark plug wire. I moved it in every direction to see if there was a break somewhere. Nope
The Flywheel does have some damage from a wrong part (ING plate) that had been installed by someone else. See image
Have 0.01" air between the fixed coil and the flywheel poles
I am stumped
Any good words? IMAG0003.jpgIMAG0004.jpgIMAG0005.jpgPXL_20250320_001724526 - smaller.jpg


#2

Tiger Small Engine

Tiger Small Engine

skippymud said:
Hello All

Stihl 090
Actual age unknown
Guessing 1978

First, I feel not so smart right now. Today is the day I can't diagnose the cause behind no spark on an electronic ignition setup

Coil tests good at 7 Ohms
Kill switch is disconnected
New ignition module
New Ignition mounting plate. The previous plate was the wrong one for this saw, or was cheaply made and therefore did not offer the correct clearance
There is perfect continuity through the spark plug wire. I moved it in every direction to see if there was a break somewhere. Nope
The Flywheel does have some damage from a wrong part (ING plate) that had been installed by someone else. See image
Have 0.01" air between the fixed coil and the flywheel poles
I am stumped
Any good words? View attachment 70751View attachment 70752View attachment 70753View attachment 70754
Click to expand...
Is the new ignition coil OEM or aftermarket? Compare the two coils with multimeter. Is the choke/run/stop lever working properly? Have you tried different spark plugs? How are you checking spark? Have you tried with and without kill wire attached to coil?


#3

skippymud

skippymud

Tiger Small Engine said:
Is the new ignition coil OEM or aftermarket? Compare the two coils with multimeter. Is the choke/run/stop lever working properly? Have you tried different spark plugs? How are you checking spark? Have you tried with and without kill wire attached to coil?
Click to expand...
Hi Tiger
I bought an entire ignition coil assembly which included the coil, ignition module (orange) and the mounting plate, all by MFR Wagner, so aftermarket. I am also fairly certain the previous setup was aftermarket b/c the mounting plate didn't seat correctly and caused the coil to make contact with the OEM flywheel.

I tested both coils, the NEW WEST in the picture which was what came with the saw and it tests at 7.1 Ohms. The new Wagner coil tested at 4.5 Ohms out of the box. There is no kill wire currently installed in the unit. I have two different spark testers and tried both. See pic. For the tester that uses a spark plug, I have tried several different plugs. I am miffed

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#4

StarTech

StarTech

Service manual suggest replacing the flywheel. Also ring shaped magnet strip is missing

1744214682922.png
1744214735962.png
1744215061873.png


#5

skippymud

skippymud

StarTech said:
Service manual suggest replacing the flywheel. Also ring shaped magnet strip is missing

View attachment 70758
View attachment 70759
View attachment 70760
Click to expand...
Thank you, StarTech. I have purchased a new flywheel


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