Atomic 4 issue

[DaveK]

Hi! Yes… I’m a newbie here and this my first post.

Recently bought a C&C 29 w/ Atomic 4 engine. First boat I’ve had that has an inboard. Had been running well for most of the summer but, now it just dies on occasion and starts back up most of the time. Doesn’t sputter and doesn’t seem to correlate with temp, speed or anything else I can think of. I’ve also bought and swapped out lots of parts from Moyer Marine and I’m running out of ideas. That’s why I am posting here.

Parts replace so far; plugs, wires, cap, rotor, condenser, coil, new carburetor, rebuilt mechanical fuel pump. Also pulled gas tank out and cleaned (major pain). Replaced all hoses. Made sure vent tube was also clear and rebuilt water pump / impeller.

Last night, I jumped the +12 volts from the coil directly to the battery. It died at the dock after about 5 minutes.

I really appreciate any ideas! I’m out of ideas…lol

Thanks
DaveK

[Pura Vida]

I can't speak to the problem but you my want to hit the C&C groups at some point. There is a lot of experience with "the bomb" in the 27 group. Anyway, welcome and by the way where is your boat?

[phorvati]

Moyer has a great forum. So make sure you register there and read through. I will bet its electrical.
Which coil did you put Internal or external resistor. Also, try to mount the coil on the bulkhead instead, that way heat from the engine block and vibrations will not affect it.

"Last night, I jumped the +12 volts from the coil directly to the battery. It died at the dock after about 5 minutes"
Why did you do that. Did it just stall while hot? Stalling while hot can be due to lack of gas or bad coil. Bad coil is hard to diagnose. When hot it just dies, but when when it cools down it runs ok and the resistance across the terminals is OK. You might have gotten the wrong coil.
Hows idling? Did you notice any problems.
Make sure the sparkplug cables you got are not cheapos. This is one area where you shouldn't try to save money. Champions and high end wires is a must.
Aslo add another blower to blow air into alternator/distributor area. 3 inch would be fine. It can be an inline blower but make sure you hook it up to blow air into engine room. It gets so steamy in there (especially if engine is raw water cooled) that I had intermittent shutdowns untill I got some fresh air in that cramed engine compartment. I would sometimes track the problem to condensation in points. Or the vibrations would cause the high voltage + lead to slip off the coil.
Good luck,
Petar

[Alan Wheeler]

I suggest it is a fuel issue. Most likely vapour locking when the engine gets very hot. It could be that the Carb bowl is boiling the fuel or maybe somewhere in the fuel lines and pump system it is getting too hot and vapourizing. Also check that an electric fuel shut off valve (usually fitted to carb/fuel entry point) is there or not. If present, it maybe getting a faulty electrical feed and shutting off. Don't panic if you can't find one, it is not a normal fitting for these engines, it would have been retro if it is there. But they are very handy to have to ensure the fuel is shut off to the carb when the engine is shut down. So may have been added.
Good work feeding the 12V supply and by passing all electrical. That rules out a lot of possible suspects. I doubt it is electrical at all. Electrical issues in the ignition side like coil, points, capacitor etc, will cause telltale misses and backfires. No, I definitly suspect a fuel vapour problem. Do ensure you have a very good air supply into the engine compartment.

[DaveK]

Wow…. Thanks for the response!

Pura… the boat is on the very very low Lake Travis and I have asked on the C&C forum. Not much traffic there though.

Phorvati…. I jumped the coil directly to the battery in order to rule out any wiring or switch issues. That was something that was in the Moyer Marine manual. Thanks for the ideas on air flow. I wondered about that.

Wheels…. Nope.. there is no electronic fuel shut off valve. There was a check valve at the tank. But, I removed it. This is a mechanical fuel pump. I believe the retro ones fitted with electric fuel pump have that sort of switch. That is an interesting thought about possible vapor locking. I haven’t heard that word in a long long time..lol.

Just trying to remember how a basic engine works from the ‘70s is killing me. Every time I work on it, I keep thinking about how I did that on my ’69 VW bug..lol. I guess one of the resounding things I’m hearing here is AIR flow. Should I leave the blower on all the time I’m running the engine? Also… I didn’t have a lot of time today but, I did change the points. I like the new points better. They had a set screw to hold the ground wire and the condenser wire to the points. The old one just slipped them on in a slot. I did run the engine for 20 minutes and it didn’t fail but, that doesn’t mean anything.

Thanks again!!
DaveK

[irwinsailor]

When they just die without sputtering I have found the problem to be the coil. One it cools somewhat it will restart. I have had this problem a couple of times.

[hellosailor]

It sure sounds like you have replaced everything that could be a problem, from the carb to the entire ignition system. Have you also replaced the fuel filter(s) as well? If one clogs your engine should sputter then die--not just die quietly.

This is going to be one of those "d'OH!" moments when you finally do track down the really simple trivial thing we're missing.<G>

Somewhere it is either losing spark, fuel, or timing. If it was in the distributor I'd expect it to sometimes run rough, not just quit. Plain quitting sounds more like it is getting the spark cut off. Maybe there's something loose, or shorting out to the coil?

You might try poking around the ignition system with a stick (to avoid getting a nasty shock) while it is running at the dock, banging it on the coil, etc., to see if you can "motivate" a loose part to fail while you are watching it.

Compared to a cranky diesel engine with air or clogs in the fuel system, I still think a gasoline engine is no harder to troubleshoot or maintain. Couple of more parts, no big deal once you get it in "book" condition.

[Jerry]

I had an Ericson 29' with an Atomic 4 engine that was totally rebuilt by Don Moyer of Moyer Marine. First of all you won't find anyone out there that has more knowledge of these engines than Don. He is a super guy & will go the extra mile to see that your engine works as it should.
Does your problem occur when the engine compartment is open? I found on one occassion that my engine seemed to be starving for air on a very hot day. Turning the blower fan on cured the problem immediately leaving me to believe that the engine compartment wasn't getting enough of a supply of fresh air for the engine to operate properly.

[BBill]

Even though you have a new carb, have you tried rapping the carb bowl lightly every few minutes while still running? Sometimes this will show a stuck float or needle. They can stick open or shut and it's a simple way to check without taking the carb off. If it stays running the problem is likely isolated to the carb. Not 100% accurate but better than guessing or taking the carb off.

[DaveK]

Yeah… Don Moyer mentioned this to me as well about the carb. I reminded him that I bought a new one from him. We are talking about this as well via email. He is a great guy for taking the time to reply as well as you folks for helping.

I just wish it would die and stay dead long enough for me to spray some starter fluid in the carb. That way I could establish which side of the fence I should be on. It just runs great, quits, hit starter button and off we go again running just great.

I will have to try the suggestion about leaving the engine compartment open. Seems air flow issue is spoken a lot here.

Thanks again!
DaveK

[hellosailor]

Slim chance but...

How about, run the engine, and then pull the coil 12V+ wire off suddenly to cause an ignition failure.

See if that literally makes the same noises as the failures you are getting. If it does...look into ignition.

And similarly, get something big to throw across the air intake and choke it off. I suspect it will die with different sounds, eliminating the air question.

Try to cause other specific failures, see which make the closest sounds to the way the engine is dying on its own.

And if all else fails, hang a big garlic in a mesh bag by the air cleaner. I did that on an old Mustang once, and during the weekly trip to the dealer, the mechanic opened the hood one day, saw the garlic, and said "Huh?" I said hey, it can't HURT this car, can it?<G>

[BBill]

Don't know if your A4 installation has anything like this but I had a similar deal happen on a new outboard. It ran ok but every now and then would quit as if the key was turned off. No sputtering, no backfires, no nothing and then start right up like everything was perfect. It took about a yr of fiddling around to find a poor fitting electrical connector as the culprit. It had the round rolled hollow male pins that plugged into the female side. The pins were partially split and had a hole on the end. I spread them slightly to get better contact and the problem never returned. If you A4 has anything like that in the ignition system check it.

[Alan Wheeler]

I still suspect it is a fuel vapour issue in the carb, but.....
Another point you guys have made above about the carb having a plate to reduce the power. This is actually a comon practice in many engines. Very common in outboards. But it isn't as simple as JUST the plate and removing JUST that plate may not give you extra Hp. It is a combination of jetting in the carb AND the plate. It is all about correct fuel and air mixture. Changing the air flow volume also means the fule mixture must be changed or the engine will suffer from Rich and Lean spots through out it's operating range and most likely will be very fuel hungry and lacking in power. Now OK, I am not persoanly familiar with this engine we are talkign about and maybe it is JUST a case of the plate being removed. BUT , I highly suspect that is the case and would ahve thought the carb would require rejeting to suit the different Air volume.
Question, Did this stopping issue occur before that restrciting plate was removed????

[DaveK]

Originally Posted by Alan Wheeler

I still suspect it is a fuel vapour issue in the carb, but.....
Another point you guys have made above about the carb having a plate to reduce the power. This is actually a comon practice in many engines. Very common in outboards. But it isn't as simple as JUST the plate and removing JUST that plate may not give you extra Hp. It is a combination of jetting in the carb AND the plate. It is all about correct fuel and air mixture. Changing the air flow volume also means the fule mixture must be changed or the engine will suffer from Rich and Lean spots through out it's operating range and most likely will be very fuel hungry and lacking in power. Now OK, I am not persoanly familiar with this engine we are talkign about and maybe it is JUST a case of the plate being removed. BUT , I highly suspect that is the case and would ahve thought the carb would require rejeting to suit the different Air volume.
Question, Did this stopping issue occur before that restrciting plate was removed????

I must of missed something here. There is no restrictor plate on this carb. Just a brand new stock carb. This engine does have a blow back tube pointed into the air intake. I don't understand what it does. But, it takes air from inside the exhaust manifold (maybe... I think?) and blows into the carb. A buddy said it was to keep you from getting oil and crap all into your bilge.

Also... there is one other mystery wire that I don't understand. The positive side of the coil has 2 wires. 1 is obviously the +12v from the ingnition button. The other wire runs from the same place on the coil to the alternator. Does anyone know what that's for?

I'm an idiot... yes, I think I now know what that is for after typing it out. Sorry... this is painful for me (basic engine repair 101)..lol. I'm thinking that wire is to give +12v to coil while charging batts at the same time.

I also think it is a great idea to simulate (make it) die from fuel or electric.

Thanks Again
DaveK

[hellosailor]

Wheels-
I don't know beyond what I've been told, but the story on the A4 was that yes, the restrictor plate was just a quick kludge to beat import tariffs. Remember gas was cheap 40 years ago so if the engine wasn't efficient and needed a bit more of it...<G>...besides, carbs are often tolerant of abuse.

Dave-
The mystery hose *probably* is a crankcase breather hose. Normally there are unburned vapors, fuel/oil/air, in the crankcase and on cars, they used to just stick a screen over the hose and let the vapors blow out under the hood. By running the hose into the air intake instead, the vapors get sucked into the engine and combusted. So, you don't have oily vapors blowing into the engine compartment, and unburned hydrocarbons being wasted. A good simple idea. If that's the case, there may be a PCV valve in that hose, a plastic thing maybe the size of your thumb with a marble and a spring in it. (Low tech works.<G>) PCV means "Positive crankcase ventilation" and that was the start of all the newfangled emissions equipment.

Last time I saw a plain ignition coil it had two "small" wires (IIRC one hot one ground) and then the ignition hot cable top center. I know that can cary, you can pull a tachometer signal off the coil Or the alternator as well.