Atomic-4 dies at idle

[dchunt]

I have an Atomic-4 on a 1972 Pearson 36 that has always been reliable. It has spent all its life in lake Erie so it is only in the water 5 months out of the year and always in fresh water.

Today I was bringing it into the dock at idle after a good sail and the engine just died. If I remember correctly it was idling along and then stopped. I don't remember it sputtering but I was too busy trying to get it restarted to concentrate. I couldn't restart the engine. Luckily I had enough headway on (but not too much) that I could glide into the dock and stop before hitting the pier.

I tried to restart the engine after it was at the dock but it wouldn't start. I checked the spark with a screwdriver stuck in the spark wire and there was a good spark. I had also replaced the ignition with a solid state ignition (Ignitor by Pertronix from Moyer Marine) 3 or 4 years ago so I think the ignition is OK. I checked the gas tank for gas and it had 10 gallons at least. Also, if there had been a problem with a vapor lock this should have fixed it. However, I still couldn't start it.

I had a spare main fuel filter so I removed the old one (it was 2 or 3 years old) and put in the new one. There didn't appear to be any water in the fuel. It still didn't start for a while. After doing some more checking and then trying to start it again, it finally started and seemed to run OK.

My problem is that I don't want to be out in the lake when the engine dies again. How can I troubleshoot the problem to determine if it is the fuel system? I had the carburetor replaced on it a couple of years ago and have not had any problems up until now. What would be the symptoms of a bad fuel pump?

Also I have a replacement fuel pump (from when the engine was new) that has a glass sediment bowl. The current fuel pump on the engine has a metal sediment bowl. Wouldn't you normally want a glass bowl so you could see if there was water in the gas?

Any help would be appreciated.

Thanks,

Dan
Arriba

[Selkirk]

Sounds like you have correctly checked the ignition/spark process.

So it's a fuel issue.
I'd ask myself how old the gas was. If the gas is old - more than a few months - I would consider it too old to use. So I would get the old gas out of the tank, clean the tank if I could, change the fuel filter, change the fuel pump, pull the top off the carburetor so I could clean out the float bowl,put fresh fuel in it and expect it to crank up and idle well as well as reving up smoothly.


The float bowl:
In case you are unsure, the float bowl acts just like the tank on the back of your commode. There is a float, a small valve on the input side and a teeny weeny hole somewhere in the bottom of the bowl for the fuel to get out. Blow out the teeny weeny hole with compressed air - you can buy a can of compressed air at a computer supply department.
If I was doing it, I'd buy myself some gasket material before I started so that I could make another gasket if I tore the original when I took the top off the carburetor.
If you are not too sure about your abilities and don't want to do the carburetor stuff, it'll probably be alright anyway. I just like to go through everything when I get into something like what you have.

Fuel pump:
Sooner or later it's going to fail. Change it now. Check out the old one and save it for an emergency if it pumps.

[dchunt]

Selkirk, how does a fuel pump fail? Is there a diaphram in it that fails? Am I better off with the mechanical fuel pump for the A4 or the electric one?

DAn

[Pater]

Fuel pumps fail for a few reasons. The diaphrams leak (generally when exposed to fuel with high concentrations of alcohol) The valves stop sealing well (varnish, dirt, rust from old tanks,etc). the springs get rusty and lose their abilty to draw fuel through the varnish encrusted orifices, etc. Personally, I'd purchase the electronic fuel pump kit through Indigo and empty the tank, spin on a new separator/filter put enough 90 octane gas in the tank to make it back from my longest day trip, carry a spare can and enjoy the rest of the season.

[pschoonveld]

I'd look at the fuel issue more. Drain the carb into a little, clear-ish dish like a tupperware. depending on the carb your have, you might have a drain plug/bolt on the aft starbd side. Throw the dish under, pull the plug and look at the fuel. Most dodgy a4 issues are just bad fuel or dirty carbs. I got water in my tank and draining the carb showed it exactly.

If you don't have the draining carb or don't feel comfortable messing with it, pull the carb and put it into the dish. Emptying it out won't hurt it and will tell you if you have bad fuel.

Look for water at the bottom as well as dark/tarnished fuel. If it separates out, you know exactly what you've got.

[Twoowls]

After building race car engines for forty years I bought a sailboat with an Atomic 4. Could not stand any sort of problem.They always occur just when you shift into reverse just before ramming the million dollar yacht moored next to your slip. So.........
I installed a low pressure electric fuel pump, available at any auto parts store, a new Don Moyer carb, an electronic ignition from Indigo aaaaaaand a very large fuel filter designed for a diesel truck with a water drain on the bottom of the filter. Once a week or so I just put a GLASS cup below the filter and drain the water.
So far I have not had to call my insurance carrier about that 80' Bertram next door. ( I also rebuilt the old carb as a backup. It is really easy, just keep track of the parts as you take it apart. clean everythig, blow it all out with air, then put the new ones where the old ones were.) It would also be very important to make GOOD friends with the owner of the 80' yacht.

[CalebD]

You might also consider that you could have back pressure in your exhaust system that increased as your engine got hotter.
Clean fuel + air + spark AND a clean exhaust system are all you need to keep an A4 humming, IMHO - I forgot to add cooling water.
Carb is also a good bet but consider the whole system, not just a single component. Cleaning the carb is not so difficult as others have posted.
Otherwise check in at moyermarine.com. Plenty of motor heads over there that know these old flat head engines like the back of their hands.
My best.

[dchunt]

Thanks for all your responses. They have been really helpful!

Dan

[imagine2frolic]

Will it keep running while using the choke? If so then cleaning the carb would be my choice......i2f

[corny]

Didn't see anything about changing the spark plugs. Our A4 displayed some similar behaviour at idle, though it would start again. It also was prone to fits of missing and erratic firing til it warmed up.

I pulled the plugs and they looked nasty. Changed them out and all is well.