electrical blues

[ccmarsh]

I have a 1972 302 Mercruiser 5.0. V-8

Keep in mind that my boat doesn't seem to want to start. It rotates a couple times but that's about it.

My question is about my ignition coil a 12v w/internal resistor.(It's not a Marine ignition coil because at the time I bought it I didn't know if there was any such thing as a marine ignition coil.....come to think of it I still don't)

Anyways, I notice the eyelet on the wire leading to the positive side of the coil was a little tatered so i decided to replace it. After I had done so(with solder and heat shrink wrap) I wanted to find out how many volts were going through the wire, 11.50v. Now get this. When I connected the wire to the positive side of the ignition coil and tested the wire again the voltage dropped to about 4. What's the deal?

Chris

 

[Reel Poor]

Re: electrical blues

The ignition points are probably closed (creates a dead short), if not you may have a faulty set of points or the wire leading into the distributor may be shorting, or a faulty tach. To eliminate a tach problem disconnect the tach lead from the negative side of the coil. Remove the dist cap and see if the points are closed. If they are either turn the engine until they open or place a small piece if paper between the points (matchbook cover or similar works well) then recheck the voltage. It should read the same as if the positive wire were disconnected from the coil, give or take a couple of tenths.

BTW, 11.5 volts is a sign of low battery voltage. Check voltage at the battery, should be 12.5 + .

 

[Haut Medoc]

Re: electrical blues

The older Fords have an external resistor, your coil should say, "use with external resistor".....
Anyway what Reelpoor says is true, the battery should have 12.5V no matter what......
& while cranking it should maintain that 12V from the solenoid, then drop down when the engine is running.......
What color was the one you repaired, there should be more than one wire on the + side of the coil....
Charge the battery first & see what happens.....
Has this engine ever run?......
Welcome to iboats, btw.......​

 

[ccmarsh]

Re: electrical blues

I don't know how to tell if they are closed or open.

 

[ccmarsh]

Re: electrical blues

It does say use with external resistor...the color of the wire I repaired was...well one was white w/grey strip and the other was a tan I guess...yes this engine has ran before.

Chris

 

[Bondo]

Re: electrical blues

I don't know how to tell if they are closed or open.

Take the distributer Cap off,+ Look......

By the sounds of things,..... Your Battery is Whooped.........

Get it Charged Up, or Replaced,+ things might go alittle smoother.........