Trouble shooting downed atomic 4 after epic fail on my part


Member III
Normally this rather tired atomic 4 runs perfectly.
After not sailing for a couple months, thought I'd run the engine just to keep things moving.
Unfortunately I made a couple errors up front that may have completely screwed me.

The first is I forgot to open the fuel line.
The second is I remembered to open the raw water intake line.

With choke pulled out, the engine started up and ran for about 15 seconds, then died.

That was unusual, as this engine after quite a bit to get running well and good every time never does this. She starts every time, even after a month of non use.

Not realizing I'd forgotten to open the fuel line (and I have a electric fuel pump), I tried again and again.

Now the fear for anyone knowing atomics is running so much water through the engine, it backs up eventually and you get water in your engine, which is a very bad thing if that happens.

Luckily, when I rebuilt my exhaust system, I added an additional valve at the low point after where hot exhaust air and water are mixed, so should I ever wonder if I've got too much water in that area endangering the engine, I can empty the water into the bilge area and it's then routed safely out via the bilge pump. It's easy to check, and so far there was no water.

After trying to start the engine for 30 minutes, I decided to FLUSH the engine with fresh water, and attempt it another day as night had arrived and I was pretty frustrated. I use a 5 gallon bucket, and hooked up my dock hose to the fresh water rinse connection and tried starting the engine hoping to crank it long enough to fill the engine with fresh water, and shut it down for another attempt on another day.

Water did not seem to be going through the bucket, so I finally hooked up the hose the the spigot at the dock box, and turned the water on. This creates water pressure which I don't like, preferring the impeller pull the water in the engine.

After about 3 minutes, I thought I didn't want the water pressure pushing the water through and so disconnected the hose from the dock box water spigot. I thought I'd make sure the water hadn't backed up and opened the valve at the low point in the exhaust and for the first time ever water came shooting out for 1.5 seconds. Prior to this, there was never more than about 1/2 a cup of excess water to exit that valve whenever I'd check it.

Unfortunately it was around this moment I realized I'd also failed to open the fuel valve up until now...

Now things go from bad to worse...

Now the engine sounds wrong when I try and turn it over.

I've pulled a spark plug and it's getting spark.
I've checked the oil, and it's not foamy or milky.
I've pulled the fuel line off after the electric fuel pump, and with the key partially turned and fuel pump engaged, fuel definitely comes out.
When I pull any of the spark plugs, they all have a liquid between the two points where the spark happens, and I've never seen that before.
My air intake for the carb looks like it could use a cleaning.

Having the manual, and reading it after this incident, I know the atomic needs 3 things, fuel, air, compression.

I know it's got fuel, I checked.
I don't think it's got water in the engine as I checked the oil, and it's not milky.
I know it's got air, for water came out the back when it ran for the 30 seconds, and on a second attempt a couple days later (today) some more water came out for a second.

To check compression, they suggest pulling the plugs and holding your thumb over the hole one plug at a time, which I could do, but an easier test would be to simply look at my pressure guage when starting the engine and if there's pressure, it should show up as the regular pressure it runs at, and if one of the cylinders is down, that should show up as reduced pressure, no?

I'm pretty concerned as this engine once I got it running well, has been a champion every time, once running for 14hrs straight from Ventura to Catalina Island without a single hiccup. I've maintained the engine replacing the impeller every two years. Flush the engine with fresh water after every use. recently changed the spark plugs.

One thing to note, I've never seen any liquid in the spark area of the spark plugs as I see now in all the plugs, and that's alarming. I've seen oil, carbon...crud basically, but never any liquid of any type.

Anyone with an atomic ever put enough water in the exhaust to back up the water until it went back into the engine?

Any ideas what I should try next?


Dave G.

1984 E30+ Ludington, MI
What IS the liquid on the spark plugs ? If it's fuel(gas) the plugs may be fouled/misfiring. Leave the plugs out overnight and let the fuel evaporate.
If it's water(hope not) most likely having a very hard time turning over as water will not compress. Take all the plugs out and crank the engine for a bit, it should blow most of the water out. after that if you have a air compressor try to blow out any remaining water. You should change your oil and filter while it's fully drying out. Clean or replace the plugs and hopefully it will come back to life. Maybe spray a little WD40 into the cylinders to help with initial restart. I had to do something similar on a jeep that I got a little to deep in the river....:)

gareth harris

Sustaining Member
As per Dave, the first question I would ask is what does the fluid smell like?

My recollection is that each cylinder should have a compression of 30-50 psi - my manual is with my boat so I cannot verify that. A compression tester with the necessary fitting is not expensive.

Freyja £E35 #241 1972


Member III
The three things you need to run are air, fuel and spark. Sounds like you have all three. If you pulled water into the engine from over cranking it probably would have hydro locked and wouldn't turn at all.
I would clean and dry the plugs.
Another thing to check would be the condition of your fuel. Has water gotten into it ? I had a similar problem with my old A4 one spring and then discovered that I had left the fuel cap off over the winter :rolleyes:. Try starting by running a hose from the fuel pump to a container of fresh fuel.


Member III
After a lot of trouble shooting with Ken over at Moyer Marine ( a big shout out to them they're awesome!)

My water jacket is compromised, and this atomic at least is dead.

She helped our boat out of many a harbor and even crossed us some distance once driving for a solid 16 hours straight...I honestly don't know how it lasted as long as it did given how it looked.

Life goes on, and still to this day Atomic 4s are the only engine still running some after 4 decades of service, it was one bad ass little engine.

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author

Sic transit gloria mundi... :(

Totally Agree about having due respect for its faithful service.
In my youth "atomic power" was the much anticipated future!!
Soooooo.....Whatchagonna do now?