Atomic 4

[Columbia30]

I have an Atomic 4 in my Columbia 30 and it has recently started dying on me. There have been a few times as I'm motoring that it has died and other times when I'm idling. I recently discovered some water in the tank and have drained all the fuel out of the tank and lines. I have also taken the carburetor off and thoroughly cleaned it, replaced the fuel filter, and all the spark plugs. Once the fresh gas was in the ole thing started right up. My trouble now is keeping it running. It'll start right up and run on a fast idle for about 45 seconds to 1.5 minutes then die. I have adjusted the idle on it and a few trouble shooting things I can think of. Any help would be greatly appreciated!

[boatross]

Go directly to Moyer Marine Atomic 4 Engine Rebuilding and Parts. Great forum and information. Very helpful people.

Good luck to you.

[Columbia30]

Thank you I will!!

[Nemo55]

First off, get rid of that fuel tank,,cos it sounds like its getting water in again.
Then run new supply lines, and overhaul the carb again,,also check the fuel pump diaphragm if its a manual.

These engines are very simple, to repair and maintain,,oil, fuel, and cooling, filter changes, and spark plugs,,and they usually last forever.

Originally Posted by Columbia30

I have an Atomic 4 in my Columbia 30 and it has recently started dying on me. There have been a few times as I'm motoring that it has died and other times when I'm idling. I recently discovered some water in the tank and have drained all the fuel out of the tank and lines. I have also taken the carburetor off and thoroughly cleaned it, replaced the fuel filter, and all the spark plugs. Once the fresh gas was in the ole thing started right up. My trouble now is keeping it running. It'll start right up and run on a fast idle for about 45 seconds to 1.5 minutes then die. I have adjusted the idle on it and a few trouble shooting things I can think of. Any help would be greatly appreciated!

[Ex-Calif]

Originally Posted by Columbia30

I have an Atomic 4 in my Columbia 30 and it has recently started dying on me. There have been a few times as I'm motoring that it has died and other times when I'm idling. I recently discovered some water in the tank and have drained all the fuel out of the tank and lines. I have also taken the carburetor off and thoroughly cleaned it, replaced the fuel filter, and all the spark plugs. Once the fresh gas was in the ole thing started right up. My trouble now is keeping it running. It'll start right up and run on a fast idle for about 45 seconds to 1.5 minutes then die. I have adjusted the idle on it and a few trouble shooting things I can think of. Any help would be greatly appreciated!

After it dies does it restart?
Will it run off idle? That is if you keep the throttle cracked off idle does it keep running or quit regardless of throttle position?

- idle circuit blockage - runs at high idle then dies sounds like a low idle circuit blockage - or
- fuel starvation or flooding. The fuel bowl empties aft a minute and a half = fuel blockage. The float sinks and the fuel bowl overflows and floods the engine = should smell floaded
- dies regardless of idle after a bit then restarts after "cooling" off. Likely electrical, likely failed coil. Will test fine when cold, insulation will break down when hot.
- other electrical possibility is a cracked distributor cap. Also exacerbated hot vs. cold


Good luck.

[Marksman]

I had a similar problem with a GrayMarine. I discovered that the ignition coil would work until it warmed up and would die. After cooling off a little the engine would run fine again, but only until ...... worth a check any way.

[Ex-Calif]

Originally Posted by Marksman

I had a similar problem with a GrayMarine. I discovered that the ignition coil would work until it warmed up and would die. After cooling off a little the engine would run fine again, but only until ...... worth a check any way.

And to top that off I once replaced a coil with new. Then proceeded to replace a bunch of other stuff. Then found out I had a bad new coil right out of the box. Boy was that frustrating...

[Marksman]

Yes, I gave the short version of that story, there was plenty of retail therapy before I discovered the "selectively" bad coil.

[S/V Alchemy]

Blow the spider gunk out of the fuel vent line, and get back to us.

[gjordan]

Plugged vent lines take much more than 90 seconds to stop a motor. If you still think it might be a plugged vent, just loosen your fuel cap and try to run it. Dont forget to retighten it. Automotive vacuem gauges usually also have a fuel pressure scale on the guage. Buy a few hose barbs of the correct size and some rubber hose to connect the vacuem/pressure gauge between the fuel pump and the carb, and see if the pressure drop is instant. New or old fuel pumps can go bad. Before you do all that pull a spark plug just after it quits and see if it is wet and smells like gas(sunken float). Harbor Freight, and most auto stores also sell ignition testers that you put inline to the spark plug, that will show if your coil is bad. These little testers cost less than $5 at Harbor Freight. Keep us posted as to the solution.____Grant.

[S/V Alchemy]

You are right, but in many Atomic 4s, either the cam is worn or the diaphragm in the mechanical fuel pump is worn or not entirely sealed or the fuel line is kinked or the fuel-water separator is cruddy...I can devise and have frequently experienced this problem in several manifestations.

The stock A4 mechanical pump creates 2 PSI, if I recall. It's surprisingly easy to defeat.

So before getting busy on the engine, it's an easy check to free the vent line, blow it out with compressed air, properly affix it with SS clamps and rule it off the "problem-causing" list.