mercruiser no spark from distributor

boatdeezy

Cadet
Joined
Jul 5, 2013
Messages
6
Hello all, I have been looking through the boards, haven't found a solution for this.

I have a 1972 mercruiser sterndrive 120

I have a good batt, fuel, and testest spark from the coil, even replaced it.

Problem is, im not getting any spark from the distributor. I have checked by pulling the wires and testing with a volt meter, and testing to see if there is any spark, none of which turn up to have any sort of juice flowing. I even took the distributor off another motor i had laying around, with the same results.

Engine turns over, just not getting any spark from the distributor, coil wire to the distributor is showing around 12v.

But nothing coming from the plug wires, any help would be appreciated, i've also followed steps in this thread http://forums.iboats.com/mercruiser...oubleshoot-points-ignition-system-335407.html

with no luck, just cant get spark from either of the distributors i have tried.

Thanks.
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,092
Re: mercruiser no spark from distributor

your getting spark from the coil tower but not coming out of the dist to the plug wire?
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: mercruiser no spark from distributor

To check for spark, remove the coil wire from the distributor cap. Hold the end about 1/2" from a good clean ground (unpainted) and crank the engine. You should get a bright blue/white spark that snaps across the gap. If no spark, try one of the plug wires in place of the coil wire. Wouldn't be the first coil wire to fail.
If you have spark this way, but not to the spark plugs, you have a bad rotor or cap.
 

boatdeezy

Cadet
Joined
Jul 5, 2013
Messages
6
Re: mercruiser no spark from distributor

How many volts should I be getting from the coil wire that goes to the distributor, when cranking the engine?
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: mercruiser no spark from distributor

How many volts should I be getting from the coil wire that goes to the distributor, when cranking the engine?

Which coil wire?
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: mercruiser no spark from distributor

I have a good batt, fuel, and testest spark from the coil, even replaced it.

I'm sure you meant to type something else besides testest, just not sure what. Replaced what?
 

boatdeezy

Cadet
Joined
Jul 5, 2013
Messages
6
Re: mercruiser no spark from distributor

The coil wire that goes from the top of the coil to the top of the distributor not the small black one.

I had meant to say, tested the spark from the coil wire that goes to the top of the distributor. But its only reading the same voltage as the voltage going to the + side of the coil. So im thinking its gotta be much more that needs to go into the distributor ?
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: mercruiser no spark from distributor

The coil wire that goes from the top of the coil to the top of the distributor not the small black one.

You don't test that with a meter, it's somewhere between 20,000 and 40,000 volts. Do the spark test I suggested in reply #4 and report back.
 

boatdeezy

Cadet
Joined
Jul 5, 2013
Messages
6
Re: mercruiser no spark from distributor

Ok :) ya i figured the coil should be stepping that up much more then the 12v its reading. Im going to do the spark gap test, and will post my results shortly. Really appreciate all the quick responses and help.
 
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