roundhead
ArboristSite Operative
I am not getting any spark...is there a way to test the ignition module on a stihl? I used a voltmeter and when I pull the rope, there is no reading.
thanks
thanks
Short answer is no, other than to pull the plug, open the electrode gap a little, earth the plug out to the cylinder and give it a few pulls while watching for spark. I strongly suggest that you also disconnect the kill wire while doing this as this can stop spark if there is a wire or switch fault. If you get spark without the kill wire attached but lose it when you re attach the kill wire this means the kill wire is shorted or the switch is faulty.I am not getting any spark...is there a way to test the ignition module on a stihl? I used a voltmeter and when I pull the rope, there is no reading.
thanks
Very simple, Disconnect the kill switch wire, take the plug out of the cylinder and ground it back to the cylinder and watch it as you quickly pull the starter rope.
thanks I did try that, just not w/o disconnecting the kill switch. I will give it a shot. it is for a BR 400 backpack blower so I have never worked on one of these before. the parts are not as many as my saws. the flywheel is alittle bit tougher to get to.
Short answer is no, other than to pull the plug, open the electrode gap a little, earth the plug out to the cylinder and give it a few pulls while watching for spark. I strongly suggest that you also disconnect the kill wire while doing this as this can stop spark if there is a wire or switch fault. If you get spark without the kill wire attached but lose it when you re attach the kill wire this means the kill wire is shorted or the switch is faulty.
It may also pay to check the gap between the module and the flywheel.
Failing all this, it's a new module.
Well, you are an old fart, as that only works on older saws that use points or an external trigger.
Most current CDI type coils (post 1970s) have Darlington transistors, diodes, capacitors & resistors
in them, not just two simple windings.
Heres a sample diagram for a Stihl CDI type coil from the 1970s.
Wow, this is my kind of thread. I just learned some real cool stuff. Thanks to all!
The newer coils have a PIC microprocessor in them... probably to handle the timing advance curve and programmable rev limiting. After spending a career in electronics I was surprised when a Stihl rep showed an unpotted ignition coil assembly and I recognized the markings on the processor on the printed circuit board to be a Microchip PIC processor.
BTW, a neon light would make a good tester and would be much easier to see than looking for a blue spark while the plug is sitting exposed on the side of the blockI was using one of those testers with a neon light in series with the plug. The saw would start easy and make one successful cut and then die on the second. With this neon light I could see the spark stop. When I replaced the plug the problem went away. I will not tell you all the things I did before replacing the plug.
BTW, a neon light would make a good tester and would be much easier to see than looking for a blue spark while the plug is sitting exposed on the side of the block
Interesting failure... The plug would have to go open circuit for the light not to flash i.e no current for the bulb. I wouldn't think that a shorted plug (much more likely occurrence) would NOT kill the coil output completely... but it might. This would be an interesting test with your neon light.
Don't know about backpack blowers but on chainsaws the ignition modules are super cheap for Stihl, much cheaper than buying the equipment to test a module. Ebay has the modules usually for less than $20.
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