Unexplained Episodes of Stalling

Yay.

wow, talk about a parts changer!

Trader144 wrote: 2. Replace coil with a new one

Again, this won't fix the issue if you're using the wrong coil from the get go.

Hollywood, greatly appreciate the time in explaining the situation and scenarios.   I do indeed have the PCM coil (number 1230 from SKIDIM) and the Prestolite Conversion (with recently replaced ign. module) so will proceed with the recommendation of getting that ballast resistor back in place before the next run.

GottaSki, right on. My novice mind would have expected the opposite of "extra heat that develops when the total system resistance is too low" but there you have it...makes sense.

Thanks again to you both for your direction through this, I appreciate it.

MSD coils are .7 ohm. Pertronix Flame-Thrower II coil is .6 ohm. I'd really call these low resistance coils.

The #1223 coil from skidim [COIL IGNITION (FORD/GM) STANDARD IGN.
Point Type Ignitions (Used with external resistance)] is advertised as 1.5 ohm. This is basically a stock replacement for the original Prestolite coils used with points & ballast resistors.

Skip to the #1230 PCM PowerPlus coil [COIL ELECTRONIC IGNITION c/o Prestolite, Mallory or Pertronix Breakerless Electronic Ignition System] does not have an advertised resistance. I have one however and measured 1.5 ohm. So, there is no difference between this one and the first one, besides being $10 cheaper.

The whole business with bypassing a resistor for conversions is to get 1.5 ohm resistance (relied on solely from the STOCK coil) for the Prestolite (purple wire) EI conversion module. Sorta the same thing for the Mallory conversion, except it wants both full 12V (red wire) AND 1.5 ohm resisted supply (black/green wire).

Stock points setup gets .8 ohm resistor + 1.5 ohm coil.

Situation 1: Burnt ignition module
If bypass your ballast resistor and you use a low resistance coil (MSD or Pertronix) with a Prestolite or Mallory conversion you'll burn up the module. (SNobsessed is currently proving me wrong on this however). Failed modules make for sporatic running before complete failure.

Situation 2: Hot coil
Stock Prestolite, #1230 from skidim or PCM PowerPlus coils will burn up if you bypass the resistor. The points can take the lessened resistance (a total of 1.5ohm) but the coils cannot take the full 12V. Result is poor running warm/hot engine, runs fine cold.

Situation 3: Upgraded coil with points (hasn't seemed to be an issue here)
MSD and Pertronix coils can take 12V, unresisted. However, when running points and a low resistance coil MSD recommends adding in a .8 ohm ballast resistor, netting a 1.5 ohm total resistance. A low resistance coil only will probably burn up your points pretty fast.

1989sn2001_985 wrote: original prestolite ignition module I bypassed the ballast resistor as indicated in the Prestolite instructions. But that thing gets hot! Is that normal? The instructions seem to indicate that a lower resistance coils with a bypassed resistor is what is needed. Thoughts?

No, a burning hot coil is NOT normal!

So the instructions say bypass the resistor but if the coil gets not don't bypass the resistor? Rhetorical question, the Prestolite instructions (or lack there of) suck. The Prestolite has 2 wires. One tach one RESISTED voltage. The Mallory has 3 wires. One ground, one full 12V and one RESISTED voltage.

Why are you risking burning up yet another module by wiring it the same way as before?

1989sn2001_985 wrote: It's a low resistance coil, I believe 1.5.

Well then use the ballast. That is the same as the factory Prestolite coils that all used ballast resistors.

1989sn2001_985 wrote: putting ballast resistor back in place, and running ignition module directly to 12 volt source.

This makes as much sense as eating ice cream on a diet.

What is the primary resistance of that coil?? If its getting blazing hot you should probably keep the ballast resistor.

Alright, so finally at the lake.

This morning I installed a new coil (linked in previous post), and original prestolite ignition module (complements of Vince at skidim), and a new rotary (just for good measure). It fired up and I had two good test runs today. Not claiming victory as the issue was so random, but have fingers crossed.

I did want to ask about the coil. I bypassed the ballast resistor as indicated in the prestolite instructions. But that thing gets hot! Is that normal? The instructions seem to indicate that a lower resistance coils with a bypassed resistor is what is needed. Thoughts?

Not sure on the coil, reference the instructions. You may need to reincorporate the ballast resistor.

There are multiple versions of the Pertonix FlameThrower (I, II, more?). Lots of complaintes with the Pertronix, not sure they are all legit claims though. I would probably seek the Mallory conversion then an entirely new electronic distributor.

An original [points] coil will still want power through a ballast resistor but the EI module will want 12V. This is how my 351W (Prestolite conversion) came to us wired as well as the 454 (Mallory conversion). The 351W has some kind of MSD blaster coil, probably low resistance(<1ohm), and the 454 has the original coil, probably low resistance (<1ohm). I can measure the 454 coil tonight but the ignitions systems were originally wired identically.

Basically you always want 1.5 ohm AFTER the coil (ballast + primary coil winding) AND 12V to the ignitor on most conversions. I think the damage typically done when you ditch the ballast AND use a low resistance coil (<1ohm). This will burn up both the coil and the ignitor eventually.

SNobsessed and I both have the Prestolite ignitor conversion. He does not use a ballast resistor. I can't remember what coil resistance he as. I DO use a ballast resisitor. If I have a low resistance coil and he has a high resistance coil we are both wired up OK. My boat has been this way for 15 years and his about 10 so I think we have different coils.

ANYWAY, I got a DUI for my 351W so this converted distributor is going on the shelf eventually...

Now is your chance to upgrade to DUI. Get 'ER Done.

Quick Update...I had the mechanic at the marina take a look at the boat today. He is stating that when the issue occurs (stalls) and when they try to restart it, it does not have spark. So, back to the ignition module we go. I have the prestolite EI (purple wire), and got a module second hand...mechanic is stating it will not spark with the replacement module. They are trying to confirm gap now for the sensor...

That said and prematurely assuming that I do not have a prestolite module replacement I can get since they are not made...recommendations?

Prestolite instructions

1989sn2001_985 wrote: ... Waited two minutes and it started back up then I floored it. Surprisingly I made it all the way to the marina without it dying, but the second I brought it back down to idle it stalled on me...

This does raise one question, are you sure your choke is consistently opening? It's an easy check.

When you give it wide open throttle, it mechanically forces open the choke, whether the choke has opened electrically or not. When you say it ran great at WOT, it made me think of this.

Alright, so here's the update from this past weekend. The issue occurred more frequently than before, almost with every start. Sometimes it would occur only two or three times, and then would stay running. I did notice that now when the issue occurs I have to wait at least one minute sometimes two before the boat will turn over. This is a new development as I used to be able turn the boat back over again immediately when it occurred.

Most interesting was the final run of the day, I tried over the course of an hour to get it to stay running, it would consistently start but then stalled within a minute. Needing to get the boat back to the marina I decided I would go in 1 minute increments. So I turned it over idled away from the dock, it died. Waited two minutes and it started back up then I floored it. Surprisingly I made it all the way to the marina without it dying, but the second I brought it back down to idle it stalled on me. Waited two minutes then it started back up and I was able to make it to the dock.

Thoughts!? This just gets more and more odd. I do have a new coil, ignore module, and spark tester ready for next weekend...but really starting to think about other systems...

An in-line spark tester tool like this would be helpful to you. You can leave it connected for a while, till you sort things out. Then, at least you'll know if you're getting spark when it's not starting:
https://store.snapon.com/Spark-Plug-Tools-In-Line-Spark-Tester-Blue-Point--P641969.aspx

Bryon,
There are times when I prefer an analog VOM over a digital. Digitals unless they are the high end recording type, are slow to react so you won't see a momentary change in the reading. With an analog even the cheap ones, if you are watching, you will see a momentary blip in the needle movement.