My four stroke Rover EasyStart (Model No 30026w) started fine as usual and then died. No spark.
The plug is good, the gap is right and the coil is a business card away from the magnets. I suspect the coil.
Is there a way of checking a coil using continuity? My circuit tester shows open circuits everywhere; from the tip of the plug lead to every component of the coil including the tag for the cut-off switch.
Is this right? Shouldn't there be some bits isolated from each other so there is a potential difference to make the plug spark?
a quick google search netted one referal to that model number. it appears you would have the briggs sprint 375 motor.
Is the black wire coming from the coil shorting on anything? if not it would be fairly safe to assume the coil is gone.
here is a link to one for sale on ebay,http://cgi.ebay.com.au/Briggs-and-Stratton-4-Stroke-Engine-parts-Coil-Pack_W0QQitemZ300287044590QQihZ020QQcategoryZ126023QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
if you want I have a few second hand ones which I can test one and post to you for $10 + post.
I am embarrased to admit that I went back through the diagnostic process one more time for luck, tried a new plug and, you all knew anyway, it fired up like a charm first pull.
However, I would still like to learn how this sort of coil and timing actualy works. I am struggling to visualise the circuit that creates the spark.
In case you wanted a technical answer, here is the circuit diagram for a breaker-point magneto. Although the diagram shows a one-to-one turns ratio from primary to secondary, in reality it is about 100 to one: lots of secondary turns, which is probably why your circuit tester showed the secondary as open circuit. It has quite a high resistance, but you should be able to test it with a resistance meter.
