Mercruiser coil output

[yimmyb]

I have a 1980 searay with a mercruiser 350 c.i. 260 h.p. engine. It will not start due to lack of spark at the plugs. I have traced the no power back to the coil. There is 9.5 to 10.5 volts across the positive and negative terminals of the coil depending on battery strength. There is absolutely no voltage coming from the coil to the distributer. The coil was replaced with a new one and the same problem still exists.

 

[alldodge]

How long have you had the boat?
Folks replace perfectly good coils every year. Being a 1980 I'm going to assume it has points unless you advise it has been changed. The 9.5 to 10.5 volts at the coil is within limits with key turned ON. You should get a full 12V only when the engine is being cranked over. The other side of the coil goes to the distributor so the points can ground the connection which cause spark.

The first thing to do is remove the distributor cap and inspect the points. See if the points open and close as the motor is cranked over. You should see voltage on the negative side of the coil when the points are open, and see zero volts when closed. If they do open and close and there is no spark, replace the points and condenser.

This is the typical layout but yours does not have a vacuum advance

 

[Bt Doctur]

Mallory or TB IV

 

[yimmyb]

It has electronic ignition

 

[yimmyb]

The 9.5 to 10.5 volts are during the cranking cycle also

 

[Scott Danforth]

if your boat has electronic ignition, it was replaced at some time

the problem is never the coil, or 99.99% of the time is never the coil

the fact you have 10 volts means that the resistor wire is feeding the coil

if you do have electronic ignition, your module may be bad
which dizzy is in there?

 

[yimmyb]

I have examined the distributor and find no evidence of a brand name. The only things I found are a riveted in black box inside the distributor and a sticker on the outside of the distributor that says it meets marine standards and is Mercruiser compatible. The entire distributor is fairly corroded on the outside

 

[alldodge]

You will have an ignition module which the distributor is connected to. Are there any markings on it?

Does it look like one of these?

 

[yimmyb]

There is no amplifier connected to the distributor. The 2 wires go to each side of the coil.

 

[alldodge]

There is no amplifier connected to the distributor. The 2 wires go to each side of the coil.

That isn't right no matter which distributor you have. Need a Pic

 

[Scott Danforth]

post a pic of the dizzy without the cap and rotor as well.

 

[yimmyb]

It says I need a URL number to upload photos

 

[alldodge]

It says I need a URL number to upload photos

Select the other tab

 

[Scott Danforth]

or click on the little paperclip thingy just left of the A (which is left of the smiley button), upload the picture, and it will ask you how you want to display - small, medium, large, full-size, etc.

if your doing it from your phone, it may not ask how you want to display the image (java script issue with mobile phones)

 

[yimmyb]

No matter how I do it it won't let me upload a picture

 

[yimmyb]

I will pull the distributor out and look for info

 

[yimmyb]

Here is what I found. It is a Petronix ignitor (carb. E.O. D-57-22) The black box inside the distributor is marked NV5M and there is 40104 stamped on the shaft of the distributor. There is a pink or red wire which connects to the positive side of the coil and a grey wire that connects to the negative side of the coil.