Need help with 1979 Mercury 45 4.5HP

[andreipou]

Hello, I got this 1979 motor (#5398664) last spring for parts, but compression was 120 and it had good spark, so I rebuilt carb and put new water pump. Motor ran great in the tank.
I did not have boat for that and left it sitting in the garage.
Last week I put it on 12' aluminum and it did not want to start.
Back in the tank it started with drill starter and died in a few min.
No spark.
I removed kill switch wire - did not help.
I am OMC person, this is my 3rd Merc only, so can use some help.
My first suspicion is coil and with OMC I just buy new one for $25, but this one is $150, so I prefer to buy only if I know it is bad.
See pics below: Primary reads significantly higher than book says and secondary shows no continuity. Is coil bad? Is this valid test or should I check also something else?

Also, catalogs show these 2 coils for their engine:

336-4528A 2​

336-4528T 2​

Is this coil below the same? Will it work? See last pic.
336-4528A 3


Any advice is greatly appreciated.

 

[mvn]

To test the high tension side, you need to put your meter on the plug wire terminal (like you have) and on the bare braided wire in your first photo. That braided wire must make good contact with the mounting bracket.

And yes, coil in last photo will work.

Mark

 

[andreipou]

Man, I did not even realize it was a wire until you pointed me. This way it reads 554, so is this coil good or bad?
Secondary is 554 (500-600 in the book), but primary is 0.7 (0.01-0.02 in the manual).

 

[mvn]

What does your spare coil read on the primary side?

 

[andreipou]

No spare. Picture is from ebay

 

[flyingscott]

Does'nt that motor have points? And you might want to make sure that is not a phasemaker ignition. I dont remember when they stopped making it but I believe it carried on in the smaller engines for quite a few yrs. somebody will correct me if I am wrong.

 

[andreipou]

No points

 

[andreipou]

No points

 

[flyingscott]

Might want to look again. Take the red cover off. See the felt wick? Pretty sure that is for points.

 

[andreipou]

yep, points.
After careful disassembly found some cracked insulation on both green and white wires going to coil.
Will replace them and try.
Hope that is the cause.

 

[flyingscott]

yep, points.
After careful disassembly found some cracked insulation on both green and white wires going to coil.
Will replace them and try.
Hope that is the cause.

That is normal for a 7os Mercury. You will be lucky if only those 2 wires are bad.

 

[andreipou]

Yes, 2 new wires = strong blue spark is back!

Question: does this motor have timing marks that can be used with strobe light?
Can not find it in the book...