Mercury 40 1970's No Spark? Help!!

spitfireboy

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Jul 27, 2007
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HI. I Have a mercury 402 40 blueband thunderbolt ignition. it has a smashed stop switch. i bought it as a 'as seen' and currently get no spark but when disconnecting the stop switch and putting it against the engine, it sparks, so does anyone know what is wrong with it? no spark comes from either coil?
i would be grateful for advice. sincerely. jamie
:eek::confused:
 

Laddies

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Sep 10, 2004
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Re: Mercury 40 1970's No Spark? Help!!

I am not sure what you are calling a stop switch or where you are disconnecting it, but if you are disconnecting the black/yellow or orange wire (color depends on the year of the engine)wire from the switch box it should have spark inless the ign. sysem has failed. If you have a OHM meter or DVA we can help with specs.
 

spitfireboy

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Jul 27, 2007
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Re: Mercury 40 1970's No Spark? Help!!

Hi there. many thanks for replying 'Admiral'.
its the stop button on the left side of facing the recoil. the electric wire is grey.
however, i have now scrapped this engine and sold it for parts but the new owner could use some advice as he is goig to build a good one out of two 'anchors'
I have just bought a newer mercury 1982 thunderbolt which has cooling issues. I cant seem to get the gearbox off. i have unbolted all the relevant nuts and bolts as far as i can see. any ideas? :)
 

Laddies

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Re: Mercury 40 1970's No Spark? Help!!

Did you remove the trim tab and get the one under it
 

Sacalait

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Jul 25, 2007
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Re: Mercury 40 1970's No Spark? Help!!

It is likely to be a problem with the switch box.
 
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