1981 70 Merc. No spark

[hammbone_merc70]

downloaded some manuals from ebscohost and tried testing the stator trigger and swichbox the test showed that the switchbox was faulty replaced with a new unit still no spark. Do you think maybe it's the rectifer/regulator or something else. The motor was running well oneday and then the next no start. not a fuel delivery problem as i can see fuel at the carbs.

 

[achris]

Re: 1981 70 Merc. No spark

HB,

Welcome aboard...

Do you have a DVA meter or DVA adapter for a standard meter?

How exactly did you determine it was the switchbox?

Engine serial number?

Chris...

 

[hammbone_merc70]

Re: 1981 70 Merc. No spark

serial # 7177252

My father and i followed some instructions that I downloaded from a merc repair manual for testing the resistance. It was all kind of french to me but
to my electrician father it made some sense.

 

[achris]

Re: 1981 70 Merc. No spark

Stators, triggers, coils and switchboxes need to be tested with a DVA (peak voltage meter, not the same as AC). You can buy a DVA meter, or build an adapter for an existing meter for about $5... (do a search on this forum and you'll find a few circuits).

Resistance can only really check for shorts (to ground) or opens.... If there is a single shorted turn the resistance won't show it up, but it won't work...

Chris.........

 

[verado7]

Re: 1981 70 Merc. No spark

achris is right - see my post about 'stator test not accurate"- i learned a little more that day .