Engine failure after running 2 hours

[brandtj]

Hello, new member here,

I'm having a problem with my atomic 4. On Friday I ran the engine for about 2 hours, noticed some sputtering most of the way and then it died. I tried to fire it right back up and it worked, but only lasted about 5-10 minutes before cutting out again and refusing to start again. Had to get towed back to my slip. After about 2 more hours of cooling down in my slip, I tried starting it again and it started up just fine. The next day I started it in my slip and ran it in forward for about 30 minutes with no issues at at, connected to shore power. Then I disconnected shore power and ran it again, and almost immediately noticed some subtle sputtering and de-powering. What could that be? Does this sound like an electrical issue of some kind? Alternator? It seems like it's not getting the same amount of power when disconnected from shore power.

I'm not exactly mechanically savvy, so please use layman's terms. Thank you!

[Dave Neptune]

First welcome to the MMI Forum.

Sounds like a "classic" intermittent coil failure. Next time it won't start check for spark ASAP. You can also check the spark before and if it is a weak yellow and not a snappy sounding blue I would be 90% sure it is the coil.

What type of ignition do you have, electronic or the std points style?

Dave Neptune

[brandtj]

First welcome to the MMI Forum.

Sounds like a "classic" intermittent coil failure. Next time it won't start check for spark ASAP. You can also check the spark before and if it is a weak yellow and not a snappy sounding blue I would be 90% sure it is the coil.

What type of ignition do you have, electronic or the std points style?

Dave Neptune

Ok thank you I will look in to the coil! I believe I have the standard points style?

[Sam]

Dave is on target [as usual] - from the pic the coil looks almost original or very old and the connections look very rusted/corroded. Coil is good place to start.

[brandtj]

Wasn’t sure how to upload video here but uploaded it to show the spark from the coil: https://streamable.com/uul7jx . It looked a bit more blue in person. Does it look concerning?

[Dave Neptune]

A failing coil will open a broken winding when it heats up due to expansion. And when it cools and shrinks back the break makes contact and it works until it gets hot enough to open back up causing no spark.

You could have a Pertronix electronic ign under the dist cap or the std points. Just pull the cap and look.
If you have points check them well and/or replace them if the engine has not been tuned for a long time. Be sure and replace the condenser as it can cause a similar problem. Personally I recommend just biting the $bullet and going electronic as you will never have to adjust the points again, it is a PIA. The change over is easier than the adjusting. Both the Pertronix our host sells and the Indigo are excellent units and both take about the same time to install.

Dave Neptune

[edwardc]

Hard to tell for sure in the photo, but it looks like both a black lead and a red lead heading back into the distributor. If this is the case, it will be an electronic ignition. A classic points ignition has only the black wire.

[zellerj]

Take the bowl off of the carb and check for bits of debris. It could be junk in the bowl is blocking off the jet, causing stalling. Once the crap settles out it runs fine again. Could also be spark, but it is good to rule out fuel issues.

If junk is in the carb bowl, it might be a good time to clean the carb. However I could never fix my carb issue by cleaning, so I just bought a new one from Moyer and cleaned out my gas tank, and all of the fuel issues went away.

Also put a new filter in the fuel line after the pump and before the carb, and Moyer sells a nice metal one that is Coast Guard approved.

[Surcouf]

I put my money on a overheating/dying coil... I had these exact symptoms after I changed my exhaust and improperly insulated the coil from the new exhaust.