Please help. 1980 - 1981 3.6 hp

[vanin100]

I have a Mercury 3.6 hp engine. serial # 567 7114. And the issue date of 198-1981.
My problem is that for some reason when I try to turn on the engine it at times gets a spark, and other times it doesn't.
What do I need to do to always get the spark to work?

 

[galamb]

Re: Please help.

Either the coil or the ignition module (under the flywheel which is a combination stator/switchbox and trigger on this model) is probably going on you - one of them has bad windings - assuming that you don't have a wire that is grounding out some where either because of a corroded connection or some of the plastic is worn off and the bare wire is touching the block (which should be checked and corrected first if applicable).

You should hope for the bad wire because neither the coil or the module is stocked anymore by Merc.

There is absoultely no way to test the ignition module. The coil (by the sparkplug) can be tested with an ohm meter, but since your problem is intermittent it will probably test good if you look at it (Murphy's law in reverse).

To test the coil you disconnect any wires going to it and remove the sparkplug wire from the sparkplug.

Set your ohm meter to X1 ohms and put the red lead in the sparkplug boot (that would normally hook to the sparkplug) and the black lead to the black ground wire on the coil.

If you get a reading between 29 and 39 the coil is fine - above or below that, it's shot.

If that tests ok, then the problem is the module (which is the far more likely cause with an intermittent loss of spark).