Oh no, another coil thread. More ohms???

[krazzz]

BTW, at cruise, voltages less than 14 volts at alt+ are a bit low these days. Move the coil off the block when convenient. Cooler is better with coils - always.

I realize the output isn't as high as people would like but it appears to be the original alternator and at 44 years old if it ain't broke don't fix it. I have shore power so my batteries are always topped off and most of my sailing is 3-5 hour day sails so I've never had to worry about charging fully depleted batteries. If I ever start doing longer trips a new alternator is on my list of upgrades.

[Antibes]

Because of the sudden shut down it is most likely electrical, but if the coil and grounds sort out ok. Bouncing around on Lake Michigan chop for a couple of hours could really get a lot of crud bouncing around the fuel system if your fuel system is original and you usually do fair weather sailing, could have been fuel related

[roadnsky]

This from Don in a 2008 post regarding a similar shutdown situation...

"In your situation, if there is something else behaving like a failing coil, then changing coils isn't doing much more than snapping your fingers. In that case, there is a good possibility that the engine was going to start anyway when something else cooled down even if you didn't change coils.

There is at least one other item that behaves in this manner (fails from heat and cures itself when it cools), which is a faulty connection in the primary ignition circuit (some electricians call these faulty connections cold joints, I suspect because they only work when they're cold).

Please skip this paragraph if this is more than you wanted to know, but I am told by normally reliable experts that an electrical circuit sees a weak connection on the verge of failure as a localized zone of high resistance which translates into a small amount of heat build-up. As the heat builds up, the expansion created by the heat eventually causes the connection to open up (minuscule though this heat and expansion is, remember that a connection in this condition is on the virtual edge of failing anyway, even without the heat and expansion).

To keep things simple, before chasing the entire primary circuit which runs from the large battery terminal on the starter solenoid, through the ignition switch and back to the positive terminal of the coil, you could simply connect a jumper wire from the large battery terminal on the starter solenoid to the positive terminal of the coil. If the engine never shuts down as long as that jumper wire is installed, you will have confirmed that the primary ignition circuit is a cold joint in it someplace.

If the shutdowns continue with the jumper wire installed, you can check the remaining short section of the primary circuit which is between the negative terminal of the coil and the points. Sometimes the conductor in this short wire develops a cold joint where is passes under the distributor cap or at the terminal of the coil or at the points themselves.

IMPORTANT NOTE: Installing the jumper wire between the starter solenoid and the coil is the very same thing as turning on the ignition switch, so you cannot leave that wire installed except when running the engine or you will burn out the coil or kill the batteries. "

Hmmm...

[hanleyclifford]

That information from Don is especially illuminating in light of the difficulty getting a solid voltage reading with engine running.

[Shelby]

krazzz,
where did you put the meter leads when you measured the coil volts? red on coil + and black where?

[roadnsky]

krazz, if you were indeed on the positive side the voltage should be steady engine running or not. If it was not steady running you have a weak connection somewhere, perhaps the key switch.

Dave called it...

[Bratina]

krazzz,
where did you put the meter leads when you measured the coil volts? red on coil + and black where?

Tonight I tested this. Red to the negative on the coil, black to a stud on the block. Voltage bounced around just as reported. Moved the red to the positive and it's rock solid. My coil is marked +/-, although faint. Can you confirm that you checked visually the coil to ensure it was on the +?

[JOHN COOKSON]

Just to eliminate any ambiguity:
The small wire that runs to the distributor from the coil should be attached to coil -. The flow of electricity to ground will be interrupted by the points\EI when they open which will cause the voltage to "bounce around" at this terminal.


TRUE GRIT

[smosher]

The faulty reading could be the meter picking up the noise from the alternator.

Try this, twist the meter leads together and then try the measurement. The amount that the meter jumps around should go down.

Put the meter on AC and this will show how much noise is in the circuit.

With the batteries fully charged the VDC will be at MAX due to noload from the battery.

I say its the coil,

Steve

[hanleyclifford]

The faulty reading could be the meter picking up the noise from the alternator.

Try this, twist the meter leads together and then try the measurement. The amount that the meter jumps around should go down.

Put the meter on AC and this will show how much noise is in the circuit.

With the batteries fully charged the VDC will be at MAX due to noload from the battery.

I say its the coil,

Steve

The fact that the engine ran a long time and finally ran especially hard before quitting supports that conclusion but it still wouldn't hurt to investigate the primary circuit just to rule it out. Don't forget the ignition switch itself.

[krazzz]

Thanks for all the input. I will try and run back there on my lunch hour. I'll try to reply to all the comments in this reply.

1. Fuel system - I can easily rule this one out. In the last 10 hours (engine time) I have replaced the lines, rebuilt the carb, installed a MMI fuel pump, and installed a robust filter/water separator. The fuel is crystal clear. And it has been running like a top all summer. Also, when the engine died it was instant, like flipping a switch. In my experience with fuel issues you usually get more of a "sputter" as it is dying.

2. Correct terminals - I was definitely on the correct terminals. I cannot see a "+" or "-" but I have red and black wires coming from the electronic ignition. I touched the red probe to the terminal with the red wire going to it and the black probe to a clean bolt on the block. I will try the other terminal today just to check.

3. Loose connection - This is probably the second most likely scenarios and I will look closely at this. The fact that the instrument panel was replaced recently certainly opens up the possibility of a loose connection. I also have a jumper wire already made so I will keep this handy if it dies again.

4. Based on last summers problems I am still leaning toward this being the issue but I won't rule anything else out until further testing. I will probably buy a spare coil just to have on hand and add in a resistor to my current setup.

I will update in a couple hours once I have had a chance to run down to the boat again.

[krazzz]

https://youtu.be/jPdyUf9lNFk

Here is a video of the results from lunch. (sorry about the poor quality. I could have really used a third arm or a set of alligator clips on the probes) It started up and ran perfect. My meter reading with key on, engine off was 12.5 and with engine running it was about 13.5 however it bounced around again. I am wondering if it was picking up some interference from the plug wires? It's just a cheap electronic one. I have a 50 year old analog one that I will try on it next. No bells and whistles, just a good old voltage reader.

[hanleyclifford]

That is attempted (coil) murder. Just to put this voltage thing into perspective have look-see at the link below. Talk about getting under the (voltage) limbo stick!http://www.cdxetextbook.com/electric...esistcoil.html

[Dave Neptune]

krazz. the coil should be marked right on the top by each terminal. I have not seen a coil without the +/- embossed for proper hook-up.

Dave Neptune

[krazzz]

krazz. the coil should be marked right on the top by each terminal. I have not seen a coil without the +/- embossed for proper hook-up.

Dave Neptune

I am pretty sure it is marked, I just don't have enough access to it to see that without removing the coil. I can barely reach the coil to probe it.