No spark, possible coil issue?

[Nige1975]

Hi all.

Firstly apologies if this is in the wrong forum, I'm a newbie on here so I'll figure it out as I go along.

I have a sovereign XS440A mower which I believe has a SV150 engine, I went to start it after it being stored over the winter and there was spark but no fuel, after a carb strip down and clean this resolved the initial issue and it fired up and ran without issue.  I stopped and started it a good half dozen times, each time it started and ran well.  I loaded it into the back of the car and headed to my parents (whose mower it is) to cut the grass, upon getting there it didn't start.

I did further checks and identified that now it is not sparking.  I put fuel direct into the carb and attempted to fire it up but there was nothing.  I removed the plug, cleaned it and tried again but no joy; I earthed the plug to the engine and pulled it over and there was no spark, likewise when I tried a different plug.

I then focused on the coil and the kill switch.  The kill switch appears to be ok as when the handle is released it is shorted to ground, when pressed it is open circuit.

I tested the coil and although it appears to test ok (based on information on the web) I have my doubts.  Resistance between the HT lead and ground is approximately 5K Ohms, as well as between the HT lead and the tab for the kill switch.  However, when I do a continuity test between ground and the tab which the kill switch connects to, it is short circuit i.e. tab appears to be grounded.

Has anyone come across this before or know what resistance the tab should be when the kill switch is not connected.  I would have thought the resistance should be high or open circuit, and only shorted to ground when the kill switch is connected and the handle is released.

[Mick]

Hi, and welcome to TGMF.

Just make sure the HT lead isn't damaged where it goes through that metal clip, just in case its sparking across there instead of the plug, and check for a spark without the stop wire connected to the coil, then if still no spark then I'm afraid your coil is dead.