Unexplained Episodes of Stalling

Bryon,
Yes, intermittent electrical problems can be a real PITA. A real high end VOM would come in handy to record any voltage drops.

1989sn2001_985 wrote: So, all that said. Suggestions on what else may be beneficial to test? I just planning on continuing to run it like this for rest of weekend to see if it will stall with dash bypassed entirely for ignition power. Thanks again everyone and hope everyone's holiday is going well.

Did you get any voltage readings? Although the problem may be intermittent, get the VOM out and see if you can detect a problem. Wiggle the ignition switch and the wiring connections.

Alright....on the water....here is what has been happening...

Arrived Saturday morning, got boat in water. Started up fine. Idled to gas dock, put 10 gallons in, started up again fine, idled away from gas dock STALLED!   Started right back up, cruising at 20mph, split second loss of power, but did not stall out, made it to dock.

Let sit, and then started troubleshooting. Was able to recreate the stall several times...sometimes I would have to wait a minute or 2 for it to restart, but I could usually get it to turn over. Confirmed that ignition system was wired properly and have a coil that meets requirements of the pertronix.

For troubleshooting, I wired the positive terminal of the coil directly to the positive terminal of the battery. Starts up and runs. Have put 2.5 hours on it since, not stalling. Far from claiming victory (of at least isolating to a wiring issue between the dash and coil) becuase sometimes it would run without issue for days before cropping back up again. Also, I am disconnecting the coil when engine not started.

So, all that said. Suggestions on what else may be beneficial to test? I just planning on continuing to run it like this for rest of weekend to see if it will stall with dash bypassed entirely for ignition power. Thanks again everyone and hope everyone's holiday is going well.

Could also run it from a small can - to rule out the entire fuel supply chain.before pump.

You're right to suspect whatever was last touched. I even like to test each replacement item or group items with a run test between procedures just to prevent troubleshooting difficulties. I like to do all the new stuff in Spring each year rather than Fall so that I can prove out each new item.

For example I won't go and replace all plugs, wires, Cap and rotor, fuel filters, or impeller and t-stat at once. I might group a few together. A bad wire or defective plug or defective new pump is easier to troubleshoot if you start briefly between replacements. Just my preference. Adds a little time but can save much more.

The igniter will have a minimum coil resistance spec.   
So the best case is to actually measure the coil resistance, and add the resistor to match.

On boats where this is ignored, I've witnessed the Voltmeter actually bounce at idle in proportion to RPM. Followed in a few seasons by the symptoms above.

Read the install directions and don't go bypassing the ballast resistor because someone once said so.

I would getting a new coil and module if I were you. Don't fool around with faulty electronics.

I also have a Prestolite EI module (purple wire). It was already on the boat when we bought it 15 years ago, too bad they are NLA.

Jumping to conclusions,you don't even know what module is even in yours. If it is like Pauls go for it,but you gotta know first.

I have one I'll sell cheap

ah! I understand now, OK, will have to wait until the weekend when I can get some pictures, details. Thanks again everyone.

GottaSki, hear you loud and clear.

SNobsessed, I failed to take a picture, but I did write down "prestolite marine distributor sae-j1171" I know the sae # is genral, I could not read the exact model number very well. Its been in place for about 5-6 years, I believe.

If we are convinced this module needs to go despite the addition of a new coil and resistor, maybe I should buy a new one this week and have it on standby for the long weekend??

Again, appreciate all the expertise.

I understand it doesn't make sense at first.

With these boats fuel starvation is the typical diagnosis with stalling out under heavy load, but almost never occurs in neutral or low-flow conditions, it will manifest at highest speeds first. Your description was contrary to that, once it occurs after use, you said it can reoccur even in neutral.

If you still want to check your fuel system, make certain the tank vent is open, and the barb fitting on the tank outlet is clear of debris, those are the most common points of failure.

Consider electronix are unlike a fan belt or light bulb. They will fail in a myriad of ways, from entirely open or resistively shunted (easy) to more subtle and fail at certain temperatures, certain air gaps, conditions etc. and this is likely one of them...
You would not believe the processing that can occur on a two-wire part.

Failure analysis of mixed signal Hall effect sensors is my bread and butter. I diagnose similar and more complex automotive components, from ignition, crank sensors, proximity sensors, as well as stepper motor and LED display drivers, and find the point of failure to the sub-micron level when necessary.

I've seen how the sausage is made, and also know how it goes bad.

Concur,
The EI was overstressed in an out-of-spec high current condition, and now fails under high ambient heat even if the coil's primary resistance was now corrected.

Its a toxic environment for electronics, high heat, high current (which was exceeded)   and suppressing the back-emf of a couple hundred volts from the coil, 200 times per second and more.

How is your coil mounted? If its mounted sideways than move it upright or get an epoxy filled coild like the msd blaster.
oil filled coils don't like to be mounted sideways. some run forever like that without issue but most do not.