Grounding issue no spark

Gawdtilla

Cadet
Joined
Jun 22, 2021
Messages
13
I am currently having an issue with my 89 470 mercruiser 3.7l 165hp, I am not getting any spark in my spark plugs from the distributor. I have narrowed the issue down to a grounding issue it seems but I don't know how to proceed. It has new wires, ignition coil, cap, points, and condenser and it gets almost 12 volts as it has an external resistor. I removed the ground wire from the coil and stuck a piece of paper between my points and checked them. The left side has no continuity ( one wire on point and one on a good ground), however the right side has some continuity as measured on the voltmeter. Now question is how do i find the ground fault? I am at a bit of loss on how to proceed. Someone had mentioned that the clamps for the condenser are a one time use and can be causing it since it wasn't replaced, or maybe a lose ground wire ( haven't checked).
FYI: points are gapped and all is set to manual specifics, strong compression on all 4 cylinders too and i have almost 12 volts going to tip of cap too.
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,346
With the paper between the points and 12v to the + side of the coil, jump the points contacts quickly off and on , you must get a spark. Remove the paper, crank the engine ,you must get a spark.
Spark in the 1st test and no spark in the second test indicates the points are not making contact or are not closing to make contact
No spark in the first test indicates a bad coil or the wire from the - side of the coil to the points is open
 

Gawdtilla

Cadet
Joined
Jun 22, 2021
Messages
13
With the paper between the points and 12v to the + side of the coil, jump the points contacts quickly off and on , you must get a spark. Remove the paper, crank the engine ,you must get a spark.
Spark in the 1st test and no spark in the second test indicates the points are not making contact or are not closing to make contact
No spark in the first test indicates a bad coil or the wire from the - side of the coil to the points is open
Oh man thank you so much, it ended up being the ground wire that leads to the - side of the coil !! Got it running now thank you !!!!
 
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