Ignition Coil Mercruiser 3.0 L

Chemdawg

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Aug 31, 2013
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Hello everyone. Not sure if this should go here or under the electrical forum. Figured here since it's engine related. So my boat was running at the end of the season, and I parked it over the winter. Now I have it out of storage, and was going to fire it up for the first time to set the carb up after the carb rebuild. Wont' start. Checked fuel. That's good. Checked spark. NONE. I took the wire right off the coil and put it close to metal like I normally do, and turned the engine over. No spark coming from the coil. Checked the 12v at the coil. Good. Checked the ground at the coil and that was good. Is it possible that my coil went bad? Seems weird that it's been sitting and now I have no spark.
 

Chemdawg

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One thing I forgot to mention. The coil was already on here when I got it, but it says on the side of the coil that an external resistor is required. I do not have a ballast resistor. I checked the ohms of the coil, and on the low voltage side its 1.5 ohm, and on the high voltage side it says 8.6. Not sure if this helps at all.
 

alldodge

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Hello everyone. Not sure if this should go here or under the electrical forum. Figured here since it's engine related. So my boat was running at the end of the season, and I parked it over the winter. Now I have it out of storage, and was going to fire it up for the first time to set the carb up after the carb rebuild. Wont' start. Checked fuel. That's good. Checked spark. NONE. I took the wire right off the coil and put it close to metal like I normally do, and turned the engine over. No spark coming from the coil. Checked the 12v at the coil. Good. Checked the ground at the coil and that was good. Is it possible that my coil went bad? Seems weird that it's been sitting and now I have no spark.

Need to know your engine serial number or at least the year. Need to figure out what ignition system you have, my guess is points since you have a coil which needs an external resistor. The resistor in question is actually inside the wire going to the coil.

Going under the assumption that you have points for now. Do you have a tach? If so go to the negative side of the coil and remove the gray wire from the coil and try to start.

Take the distributer cap off and check cap, rotor and see what you points look like. Determine if the points are adjusted correctly
 

Bondo

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Hello everyone. Not sure if this should go here or under the electrical forum. Figured here since it's engine related. So my boat was running at the end of the season, and I parked it over the winter. Now I have it out of storage, and was going to fire it up for the first time to set the carb up after the carb rebuild. Wont' start. Checked fuel. That's good. Checked spark. NONE. I took the wire right off the coil and put it close to metal like I normally do, and turned the engine over. No spark coming from the coil. Checked the 12v at the coil. Good. Checked the ground at the coil and that was good. Is it possible that my coil went bad? Seems weird that it's been sitting and now I have no spark.

Ayuh,... The distributor, fires the coil,..... Does yer's have Points ignition,..?? If so, change, 'n set the points,....

If Not, tell Us which distributor ya got,.....
 

Grandad

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One thing I forgot to mention. The coil was already on here when I got it, but it says on the side of the coil that an external resistor is required. I do not have a ballast resistor.

Does it perhaps have a resistance wire in the ignition circuit as opposed to a discrete resistor? See purple wire shown dotted in diagram. - Grandad
 

Chemdawg

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Hello everyone. Hope everyone's having a good Easter. So I have been beating my head over this problem. I have tons of notes I've been taking, and I have studied the ignition circuit quite a bit these last few days. Something I seen on the net in a few spots was to take a test light, and go from the Positive of the coil to the negative of the coil. If the light flickers as your turning it over, your distributor is good, and it's a problem with the coil. Well, if I take the coil out of the circuit, and connect the purple/yellow wire to the pos of the test light, and the distributor black wire to the negative of the test light, and turn the engine over, the light flashes like it's supposed to. When I put the coil in the circuit, and turn the motor over, the light flashes once, then stops. Is this a good guestamate that the coil is bad? There is a sticker on the side of the distributor that says sae J1171. It looks like the deco distributor.
 

Bondo

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Ayuh,.... We still have no idea of the vintage of yer motor, nor whether the distributor has Points in it or not,....

If it's a Points distributor, Change, 'n set the points, 'n timin',.....

If it's an electronic distributor, post a picture of it,....
 

Chemdawg

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It's a points and condenser motor, and they are both new as of last year. The motor is a 1987 mercruiser
 

Bondo

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It's a points and condenser motor, and they are both new as of last year. The motor is a 1987 mercruiser

Ayuh,.... Take the distributor cap off, with power to the coil's (+) terminal, each time the points open, 'n close, the coil fires,....

Short across 'em, 'n the coil fires,....
 

Chemdawg

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Ayuh,.... Take the distributor cap off, with power to the coil's (+) terminal, each time the points open, 'n close, the coil fires,....

Short across 'em, 'n the coil fires,....

Thanks for the response Bondo. I'm not sure I understand what your telling me to try by shorting across the points.....
 

Bondo

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Thanks for the response Bondo. I'm not sure I understand what your telling me to try by shorting across the points.....

Ayuh,..... Read This, This, 'n This,..... I don't think you understand how points ignition works,.... The 1st This explains it,....

All 3 are found up in Don'S Adults Only section, at the top of this forum,....
 

Chemdawg

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Aug 31, 2013
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Thanks Bondo. I figured it out. The points must have had a film on them or something from sitting. I used some very light wet sand paper, and ran it through a couple of times, and bingo. Runs like a dream.... I'm going to spend the money and purchase the electronic upgrade here soon. No more dealing with this.

Thanks again everyone.
 
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