1988 merc 3.0l ignition / spark help

amadus98

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Apr 16, 2012
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Hello all,
I've tried the search with no luck what I'm looking for is a wireing diagram for a 1988 merc 3.0l (181cid). I'm having a no spark issue and need to trace my problem out. Any help would be greatly appreciated. I found a manual #24 but that's not for my year and I've found differences between it and what I have.

Thanks in advance .
Andreas
 

amadus98

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Apr 16, 2012
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Re: 1988 merc 3.0l ignition / spark help

My bad I've got manual 26 not 24...
 

amadus98

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Apr 16, 2012
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Re: 1988 merc 3.0l ignition / spark help

thank you for the fast replies,
I changed the points and condenser out to the electronic upgrade from serria. I'll take a look at the manual. Again thanks for the super fast responce
 

Don S

Honorary Moderator Emeritus
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62,321
Re: 1988 merc 3.0l ignition / spark help

The manual doesn't have information about a Sierra electronic upgrade for your igntion. The manuals cover OEM parts only.
 

amadus98

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Re: 1988 merc 3.0l ignition / spark help

The manual doesn't have information about a Sierra electronic upgrade for your igntion. The manuals cover OEM parts only.

Thank you, this should get me to at least get the coil tested right.
Just fyi I have installed new plugs,wires,cap,rotor, and electronic ignition .
 

Don S

Honorary Moderator Emeritus
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Re: 1988 merc 3.0l ignition / spark help

Did you install the electronic module because it didn't have spark?
 

amadus98

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Re: 1988 merc 3.0l ignition / spark help

Did you install the electronic module because it didn't have spark?

The points were pitted and i dont know when last tuneup was for the boats is new to me, yes and for it to be more reliable/maintenance friendly
 

amadus98

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Re: 1988 merc 3.0l ignition / spark help

ok im at a loss......
Ive checked everything per Don S link and still no luck.

I have spark at coil.
5.9v at (+) side of coil
continuity from tower to (+) and (-)
purple wires check out. I checked them all the way to carb and alt.
key switch is ok.
New cap rotor and upgrade electronic ign....

WHAT AM I MISSING.

oh and there is no saftey cut off at dash or laynard.

Any insite would be appreaciated
 

AL350SEARAY

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Jul 2, 2011
Messages
33
Re: 1988 merc 3.0l ignition / spark help

Try looking up electronic conversion kits on yahoo. They have a few wiring diagrams and installation instructions. When i looked them over i believe they called for at least 10v at + terminal on ignition coil and a coil with more than a 1.5 ohms primary resistance from - to + on a 6 or 8 cyl. (3 ohms on a 4 cyl) It also calls for a least 7k ohms or more secondary resistance on the coil. Good luck and post your results.
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: 1988 merc 3.0l ignition / spark help

ok im at a loss......
Ive checked everything per Don S link and still no luck.

I have spark at coil.
5.9v at (+) side of coil
continuity from tower to (+) and (-)
purple wires check out. I checked them all the way to carb and alt.
key switch is ok.
New cap rotor and upgrade electronic ign....

WHAT AM I MISSING.

oh and there is no saftey cut off at dash or laynard.

Any insite would be appreaciated

Spark at the coil, but not at the plugs. Replaced cap and rotor.... Ok, what's left?

Maybe the lead from the coil to the dissy????? Just a wild guess like... :facepalm:

Chris........
 

amadus98

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Re: 1988 merc 3.0l ignition / spark help

UPDATE!!!!!!!

First of all id like to say thanks to all that replied and help out......

OK so after checking everything the last thing i did was cut into the wire harness to check for a short. I metered all the wires from the quick disconnect all the way to the coil, dist, alt, carb, and the shift cutoff switch. everything checked out fine... still stumped... Ok ive been working on cars motoecycles and enthing that has a motor... i know its something silpme i can feel it . Im over looking something , so i start back at the begining, the dist. ok i pull off the cap and something just dont look right. I reach over and grab my tablet to quickly scan the internet i look up the sierra electronic ign part just to make sure i ordered the right part number.... yup right part number. then while looking at the pic i see something.......... hmmm..... how come there are more parts pictured than what came in the parts box that showed up... after a quick inventory i noticed im missing the pickup coller that goes around the dist shaft. couls it be that simple...YES it could.. When i opened the package of new parts i noticed right away there were 2 nuts missing but dismissed it because i have plenty extra nuts in the old toolbox well i totally missed the other parts that were missing. I promptly called iboats and explaind that my new parts had been delivered missing sum parts. I could not of asked for better customer care they right away sent me out a new replacement part. 2 days later fedex shows up with the new parts and sure enough there was a collar in the box along with all the right parts. I put on the pickup coller reconnected the dist cap and went to turn on the key......VEROOOMMMM it started right up.

ONCE again id like to thank all who replied you helped me get to know my engine really well, all the infor was HIGHLY APPREACIATED.
Thanks Andreas
 

antsmands

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Apr 24, 2007
Messages
58
Re: 1988 merc 3.0l ignition / spark help

Glad to hear you got it running. I was gonna tell yo to check the ele ignition again because the one I intalled worked like a charm. Sorry it was so fustrating but so simple in the end!

Happy Boating!
 
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