Engin stalls - difficult to restart

[Graham]

Hello!

Over the past two weeks, my engine had died on me three times. The engine is running fine (all warmed up) at 1/2 or full throttle and then just stops and is difficult to restart. The starter is working fine as I can hear it trying to turn over. I have a late model A4 with electronic ignition.

As part of my spring maintenance, I did the following.
- sprayed carb cleaner into the air intake
- replaced the spark plugs
- added a secondary polishing gas filter & replaced the main filter.
- installed early warning buzzer from MM
- Seafoam in oil & gas & then did an oil change.
- installed new 55 amp alternator

Guages:
- just under 40psi oil pressure
- alternator showing a charge
- engine running cool but I'm in Lake Ontario so not much I can do about that.
- Gas is 50% new and 50% from last season. Gas was treated before winter storage. Carb was also drained.

I'm thinking it's an issue with my Carbonator so I just purchased MM's Carburetor troubleshooting video. It's a great video, but it does not mention my problem directly.

Any ideas on how to troubleshoot? The last time this happened, it took me about 10min to get the engine to restart. & yes I closed the water intake after the first 3 attempts

Thanks!

[Antibes]

How long did it run before the shut down?
Lake Conditions?
Is there a water separator on the main filter?
When you say Just stops is that sudden or gradual?

[edwardc]

Bad coil?

Next time it quits, immediatly check for spark while its in the "no start" time. A missing or weak yellow spark means a bad coil. Replace it with a new MMI unit.

[Graham]

How long did it run before the shut down?
Lake Conditions?
Is there a water separator on the main filter?
When you say Just stops is that sudden or gradual?

It stops immediately. No sputter it just stops like I hit the kill switch.

The first time it stopped it had been running for 10min.
The last time it stopped it had been running for over an hour.

Yes, there is a water separator on the main filter. It's a Sierra International 18-7945 10 Micron Fuel Water Separating Filter.

Lake conditions - 13 Celsius (55 Fahrenheit) Flat or slightly rough water.

[Graham]

Bad coil?

Next time it quits, immediately check for spark while it's in the "no start" time. A missing or weak yellow spark means a bad coil. Replace it with a new MMI unit.

Thanks, this is the part you are referring too: https://moyermarine.com/product/coil...ce-iglm_05_31/

[capnward]

Sure sounds like a coil issue. Fuel issues usually don't result in sudden shutdowns. But you should disassemble and clean the jets and other passages in your carb anyway, as shown in the video. You may have residual stuff in the carb from before you replaced filters. Spraying cleaner into the air intake won't dislodge junk in the jets. You should get skilled at removing, disassembling and cleaning the carb, jets, and passages. Do that when you replace filters.
It occurs to me that the installation of your new alternator might be a factor in this. I don't know how. I know my alternator has a wire going to the positive coil terminal.

[Graham]

Sure sounds like a coil issue. Fuel issues usually don't result in sudden shutdowns. But you should disassemble and clean the jets and other passages in your carb anyway, as shown in the video. You may have residual stuff in the carb from before you replaced filters. Spraying cleaner into the air intake won't dislodge junk in the jets. You should get skilled at removing, disassembling and cleaning the carb, jets, and passages. Do that when you replace filters.
It occurs to me that the installation of your new alternator might be a factor in this. I don't know how. I know my alternator has a wire going to the positive coil terminal.

Good advice - thanks! I'm going to pull the carb and clean it this evening following the instructions in the video.

I'm also going to see if I can source a coil locally here in Ontario. I get 95% of my parts from MMI, but I'd like to get this fixed asap as having the engine stall out when coming into my slip at the marina is a scary thing.

[Sam]

Had similar problem a few years ago, sudden shutdown with difficult re-start and needed a little "rest" time. Old harbor pro suggested changing out the condenser - solved problem. Coil is suspicious as mentioned earlier.

[roadnsky]

I'm thinking this sounds like the classic coil/EI combo issue.

...I'm also going to see if I can source a coil locally here in Ontario.

If you do get a coil locally, please follow the advice in this rather lengthy but famous thread regarding coils and EI.

The important thing to note when sourcing a coil is that it is 4Ω resistance.
Otherwise, you're likely to loop right back around to having a coil issue.
The coil sold on this site is the proper 4Ω and designed to combo with EI.

[JOHN COOKSON]

If all else fails to solve the shutdown problem short across or bypass the OPSS. The last time the OPSS on my engine went on the fritz it failed with exactly the same symptoms you have described. The shutdowns sure had me guessing for awhile. I went through pretty much the same ring around the rosy that you are experiencing.
BTW: If you had a fuel pressure gauge the diagnostic effort would be much simpler - fuel or ignition side?

TRUE GRIT

[Graham]

I'm thinking this sounds like the classic coil/EI combo issue.



If you do get a coil locally, please follow the advice in this rather lengthy but famous thread regarding coils and EI.

The important thing to note when sourcing a coil is that it is 4Ω resistance.
Otherwise, you're likely to loop right back around to having a coil issue.
The coil sold on this site is the proper 4Ω and designed to combo with EI.

Thanks there is some great info at that link. I also find some good info about coils and resistance here.

I'll test our the new coil tomorrow with my ohm meter.

[Graham]

If all else fails to solve the shutdown problem short across or bypass the OPSS. The last time the OPSS on my engine went on the fritz it failed with exactly the same symptoms you have described. The shutdowns sure had me guessing for awhile. I went through pretty much the same ring around the rosy that you are experiencing.
BTW: If you had a fuel pressure gauge the diagnostic effort would be much simpler - fuel or ignition side?

TRUE GRIT

Thanks - a fuel pressure gauge is on my wishlist Does MMI sell one? I didn't see it on the site?

& sorry what does OPSS stand for?

[Graham]

So I installed a new coil this evening. Now I'll wait and see if we're good to go. In the meantime, I'll still be cautious as a sudden stall is not exactly relaxing.

Thanks for all the help everyone. It really is appreciated

[JOHN COOKSON]

Point to an underlined abbreviation with the mouse and a bubble will pop up with the meaning.

TRUE GRIT

[roadnsky]

So I installed a new coil this evening. Now I'll wait and see if we're good to go.

Why wait?
Do you know the coil's resistance?