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70 ho merc missfire

kevin

Member
Well guys it goes like this I

Well guys it goes like this I have had everybody look at my 78 merc missfire a nd still no luck
so what i have done is tried the spark jump test while running the results are as follows number 2 is strong and has a good blue spark number one is also pretty good but number three is hopeless I swap the switchbox to coil feed wires and it swaps the spark from coil to coil then i swapped the trigger wires to the switchbox and it also swaps the fault eg number two has stuff all spark and number 3 has a huge spark
could it be a wire in the wrong place or is it the trigger as the engine has been apart a few times
this one has me

anyhelp would be great
from desperate lol
 
" The trigger coils can be tes

" The trigger coils can be tested , the coils can be tested at a shop equipped with a tester. The switch box is the likely fault.Trial and error repairs result is mostly errror. "
 
" Kevin,

Did you measure th


" Kevin,

Did you measure the resistance of the trigger coils? While this is not a definitive test, sometimes it does reveal a faulty coil.

A couple of days ago, you seemed to think the problem had been solved. If the problem was the result of a wire that was connectd improperly, it would not come and go like that.

If you have an ordinary multimeter ( the type with a needle gauge), you can try this. Set the meter on milli-amperes. Touch the black lead to ground and the red lead to the trigger coil lead. When you crank the engine , the needle should be deflected. You can't get an accurate reading this way, but if you do not see any movement in the needle, the trigger is not working.

Tony "
 
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