no spark, 1981 Mercury 4.5

kurtloup

Recruit
Joined
May 30, 2011
Messages
2
Over the weekend, I replaced the ignition wires on my recently purchased 1981 Mercury 4.5 with 10 gauge wire. Once the wiring was replaced, I tried to start the motor for the first time. Unfortunately, I am getting no spark.

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I checked the continuity of the spark plug wire and it read zero ohms. I also checked the continuity of the points. There was zero ohms with the points closed and with the points open. If I tested from either contact to either the positive or negative post of the yellow and red ignition coil that you can see in the above picture, the ohms also read zero. Is this narrowing down the problem? What should I check next? Thanks.

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BMersch

Recruit
Joined
May 24, 2012
Messages
1
Re: no spark, 1981 Mercury 4.5

Kourt--or anyone else. I have the identical problem, no spark with the same motor. I've checked for continuity in many locations, across the kill switch contacts, from across the points, both open and closed, from either lead on the main coil (not stator) to ground, and all locations show short/no resistance. Any ideas what to check now?

Thanks for any help,

Bill
 

EricJRW

Chief Petty Officer
Joined
Feb 3, 2010
Messages
488
Re: no spark, 1981 Mercury 4.5

For my Suzuki, it was the condenser. I forget if I tested it (if so, I forget how), but I'd at least give that a try.
 

oldman570

Lieutenant Commander
Joined
Mar 25, 2011
Messages
1,615
Re: no spark, 1981 Mercury 4.5

Sounds like the wires from the points to the coil are grounded all the time or the points are not opening when needed.
Oldman570
 

River Boy

Petty Officer 3rd Class
Joined
Apr 18, 2009
Messages
92
Re: no spark, 1981 Mercury 4.5

This link should help on troubleshooting. Points set at .020. Don't worry if they're burnt a little. Phasemaker points fire on the 'make' unlike old OMCs. For the ignition coil itself, (the oarnge cube that the spark plug wire comes out of), you should have .1 to .2 ohms on the primary and 5 to 6 K (thousand) ohms on the secondary.
You didn't have to run #10 wire. #12 or even #14 MTW automotive wire would have been big enough and easier to work with.



http://www.cdielectronics.com/downl...guide/Mercury 1 and 2 Cylinder - 336-4516.pdf
 
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