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Old 01-05-2007, 03:46 PM
CaptainChas CaptainChas is offline
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Engine Sputters and Coughs, and Needed Choke to Run Smooth

Here's the rundown on my engine troubles, and the steps and advice from Don about what to do. At this point, I'm almost certain there's something with the carb - but for those who may have some sputtering/coughing issues (or need choke to run smooth, another issue I had), here are the steps I took to troubleshoot:

Anyway, the situation is thus on my Tartan 34C:

The engine had been running fine for approximately 25 hours of use over 2 months when, suddenly, it began coughing and sputtering - fortunately I was close to the dock and returned. Figuring it had been some time since a tune-up since I just purchased the boat, I purchased new points, condenser, rotor, spark plugs, and cap, and replaced them a couple weeks later.

The engine then ran fine again - except that to run smooth the choke was pulled perhaps half-way out. I had chosen to use the slighter hotter plugs from the original, so I thought perhaps that was related - and I was using 87 octane.

The engine then ran fine and smooth for approximately an hour - although the engine did sit for about 4 months after the tuneup while I was away before running for the hour - however, after the hour, I noticed that the temperature began to climb - reaching almost 170 - when I reduced the power to let the engine cool (traveling the intracoastal in Florida). At that point the engine began losing power, coughing, sputtering, and then quit about 15 minutes later, refusing to restart.

45 Minutes later, under tow, the engine started running fine again with the temperature at 135-140 and the choke all in the way in (no choke).

Returning to the dock, I replaced the water strainer (no temperature problems now), the fuel filter, the coil, the spark plug wires, and the points - again. When I initially replaced the coil (an MSD) everything ran fine for about 5 minutes and I thought "Ah hah!" but shortly after the sputtering began again - then I replaced the points and plug wires, which had no noticeable effect.

The engine still coughs and sputters, although occasionally for short periods it will run smooth but almost always when cool. It's acting almost as if someone, when not under load or under load, is *rapidly* turning the ignition key off and on - it's most noticeable under load. When warm, it now seems to run most smooth with the choke all the way in, although it still coughs and sputters. There isn't any preignition and I don't think it's a timing issue..

I had thought about fuel contamination, but the RACOR 200FG filter is brand new. The only additive I put in was Marvel Mystery Oil.

Do you have any additional suggestions? I tried tapping the carb float bowl to see if it was sticking and that was inconclusive. I have the mechanical fuel pump, and I have seen no fuel leaks, since the tank is higher than the engine. My current thought is to check the connection at the ignition key, and perhaps hit that was some WD40 or something similar if it's corroded.

Oh, whenever the engine starts to *really* die (as if the key was off longer and usually occurs at idle), it can be recovered by pumping throttle twice - which then returns it to a slightly coughing, sputtering, but mostly running state.

Any suggestions would be greatly appreciated - this sort of intermittent but consistent problem drives me nuts and I'm at a wit's end what else to check.


After reading the forums, I tried additional items:

Thanks to your wonderful forums, the idea of jumping from the solenoid to the positive side of the coil was tried this morning before I went to work - have to accomplish the important things .

However, it had no effect. One other thing I tried: With the key in "On" and the motor not running, I manually opened the points to see if it would spark - and it did quite nicely.

This morning when I tried to run it, there was no improvement - it still sputtered even when cold. I also turned off the fuel valve at the tank, let the engine run until it ran out of gas, opened the valve, and in about 3 cranks the engine sputtered to live - so the pump must be working as well.

Any other ideas? My last guess now is a carberator problem of some kind, although tapping it to see if the float valve was sticking didn't seem to help either. And, unfortunately for me, my carb skills are probably my worst engine skills.


Don's Response (I hope you don't mind me sharing):

If the problem remains, I’d check the short black lead between the negative terminal of the coil and the points. Sometimes the point in the wire that slips under the distributor cap will break.

There is also the issue of the time or two when you needed to have the choke partially engaged to keep the engine running smoothly. This condition is almost always caused by a small piece of dirt trying to move through the main jet. If the requirement to choke the engine returns, I recommend that you disassemble the carburetor for cleaning, or at least the main jet. The main jet can be removed by removing the 1/2” hex-headed main passage plug below the float chamber.


I'll update everyone when I take apart the carb, although in all honesty I really don't know what I'm doing with carbs. Anyone have any "gotchas" or sage advice on dealing with the carb let me know. I'll try just removing the main jet first - clean it - and replace it and hope all is well. I'll let yah'll know what I find, although the main jet removal will be fun enough since it's smashed against a bulkhead and not easy to get to on the Tartan.

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Old 01-06-2007, 04:36 AM
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jhwelch jhwelch is offline
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For cases where access to bolts is not very good I have a set of
ratcheting wrenches (say that 3 times quickly). To undo the 2 bolts
holding your carb. on may be difficult if you try to use a normal wrench.

Once it's off (and this probably won't help the sputtering issue) and
opened up I always use compressed air to blow out all the passages.

If your fuel line from your mechanical pump to the carb is a U-shaped brass pipe
this would be the time to replace it with a longish rubber one, which makes
taking the carb. off a whole lot easier, as it doesn't need to be unscrewed.
I made mine long enough so I can take my carb. off and bring it to the
front of the motor and crack it open.

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Old 01-10-2007, 01:28 PM
CaptainChas CaptainChas is offline
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Just a minor update: I ran a new wire from the negative terminal of the coil to the points with zero change in result. So, now I suppose it's off the carb.

Not that I'll have the slightest clue to do with it once it's off - I guess pull it apart, clean, replace, put it together, put back on the engine - and keep my fingers crossed .


I just read something and need your advice on my gap of knowledge:

When I purchased the Coil, the oh-so-helpful parts guy said, "MSD coil's are much better for marine applications."

After doing some looking, I noticed that they recommend a "balance resistor" on manual points - I'm not so sure my helpful person realized I had manual points on my system.

I didn't add a balance resistor - not even knowing anything about it today. Could that be the source of the problem? Or does our atomic 4 already have one - the coil I removed stated on it "FOr use with external resistance" on the outside.

Anyway, if I did run it without a balance resister, what would the results be?

Last edited by CaptainChas; 01-10-2007 at 01:41 PM.
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Old 01-10-2007, 03:15 PM
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Don Moyer Don Moyer is offline
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The most important thing to do in your case is to remove the main jet and be sure it's not restricted in any way. You can actually remove and clean the main jet without disassembling the rest of the carburetor, if that helps you.

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Old 01-11-2007, 11:54 AM
CaptainChas CaptainChas is offline
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Removed Carb - suspect Points?

Hi All,

I removed the carb today, removed the main jet, and it did seem a little bit plugged. It looked much better after a needle and a blast of carb cleaner and other cleaning. It was definitely slightly plugged and explained the need for a bit of choke.

I didn't disasemble the carb but I did remove it from the engine. I engaged in a thorough dosing of carb cleaner, through every orifice, and then put it all back together.

It definitely runs better BUT... no improvement on the occasional dying.

So, I went back to the points. Although no more than 2 hours on the points, they were crusty with something green on them.

I took some thin sandpaper, rubbed the points, put it back together - and everything ran great - for about 30 seconds or so.

Related? I don't know. I also jumped the positive side of the coil again to be sure (no improvement), but monkeying with the points DOES seem to improve things.

The third "attempt" time I readjusted the points, cleaned the green stuff again, found a fine dust around the inside of the distributor cap, rubbed it clean - and things seem to improve for short periods of time (several minutes) before starting the occassional "dying" and, with a blast of throttle, recovery. Seems to be back to idling pretty well while warm now (and no choke).

So, I'm going to get the electronic ignition (planned on that anyway) and then see what happens.

UGH! Stupid sailing season here in Florida is drifting away - but my intuition and guts tell me this is an electric problem still - I'm pretty sure we're getting fuel where we need it. And it just *feels* electric but if the electronic points don't solve it, then I might look deeper into the distributor - or a complete carb rebuild.

Might be the odd distributor issue. I don't know. Any other ideas, I'm open.


PS - Removed ignition wires to each plug without the engine making a difference in running, so it's not an odd cylinder. Also removed the plugs and found all plugs looked essentially the same.
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Old 01-11-2007, 12:49 PM
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Hey Cp'n Chas, Don and A4 Colleagues:
I am reading this thread with interest because your problems with the rough running sounds similar to those I was experiencing with my A4 just before haul out last Nov.. I have replaced the fuel filter --Racor 200FG also -- and have new spark plugs at the ready for spring when we put her back in. I added MMO to each cylinder, and hoped for the best. It will be interesting to see what happens... meanwhile good luck with your temperamental A4!
Best regards,

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Old 01-11-2007, 01:04 PM
CaptainChas CaptainChas is offline
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Additional parts

Another update: When I purchased the electronic points, I also got a new distributor cap, rotor, and coil from Moyer, knowing darn well they'd be the best/correct parts for the A4. So, once I install all those new doo-dad's, I'll be certain I can eliminate any electrical problems (I've also already replaced all the wires). I feel pretty good it's going to solve the problem and I'll also bet, now that I cleaned the main jet, it's gonna run like a little top... but you never know.

The other stuff I'll keep as spares (can never have too many of those on a boat).

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Old 01-17-2007, 08:58 AM
CaptainChas CaptainChas is offline
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Update to the Saga

Yesterday, the savior parts from Moyer Marine showed up (thanks MLK for making me wait another day) and, after about 30 minutes, I had them installed. The new parts:

Coil (The RIGHT kind)
Distro Cap (For electronic points)
Electronic Points
Crank scavenger tube (the one that goes to the flame arrester on the carb - I broke my old one).

I installed these parts, and after a coughing start, the engine ran mostly peachy.

For about 15 minutes, then it started sputtering and occasionally dying. A little choke, and the engine ran smooth as silk again.

Aha! I thought. More crap getting to the main jet.

A few minutes later, whatever had clogged it must have run through, because it started running fine without choke again.

(Side note: Damn brass lines to the choke can add issues: They are soft and easily stripped (mine were already), and of course the one to the bottom of the carb I didn't tighten enough apparently and I found a leak. So, I tightened that. Perhaps that was the problem - getting air in the line - but it was the line to choke. Replacing those brass lines with longer rubber ones is a fantastic idea and I will do it next time for certain).

In any case, she's running real nice now, although it still seems like ocassionally crap is getting in to the main jet. Since I have a brand new RACOR 200FG filter, the only culprit I see is the fuel pump. Does the bottom bowl twist off? And can I replace that part?

Probably my next purchase from Moyer will be the manual fuel pump bowl (next payday).

Anyway, taking the boat out today.

Next issue: While under load for extended periods of time, the raw-water cooled engine gets hotter than 140 - reducing throttle allows it to cool. I suspect the water impeller needs replaced. Any known issues with replacing the impeller?

So, moral the story: Sometimes it's not just one issue, it's several at once. But the A4 does purr nicely and run smooth as silk when everything is right . And I highly recommend the electronic points. I purchased new points and within 30 minutes they'd corroded for whatever reason causing sputtering and other issues - and left me pulling my hair out for days. NO more matchbook covers and adjustments! Yay!


PS - Special thanks to Don for being patient and adding his expertise to the troubleshooting. We tried everything and in the end, the big problem was the NEW mechanical points. Go figure. One thing's for sure, I'll always buy my parts through Moyer - it's good to get the *right* parts).

Last edited by CaptainChas; 01-17-2007 at 09:02 AM.
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Old 01-17-2007, 06:41 PM
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MikeB.330 MikeB.330 is offline
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I assume that you still have a mechanical fuel pump. If that's the case feel under the pump filter bowl for a knob. Unscrew the know and rotate the bail out of the way. a small tap is all it will take to remove the bowl. Reach back under the fuel pump and remove the fine brass screen unless it came off with the bowl. Do yourself a favor and order a replacement fuel bowl from MMI. It will be stainless. The OEM bowl tend to rust because the collect water in the bottom of them. The rust beaks loose and clogs your jets.

I would add a fuel polishing filter also from MMI to go between the fuel pump and the carb.

Another thing I would do is clean the entire carb. Blowing the main jet out doesn't cut it. You need to take the think completely apart. This problem will come back in short order at the worst time if you don't finish the job.

Clean the carb, buy filters and spare filters.

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Old 06-30-2009, 10:50 PM
twoowls twoowls is offline
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Smile Sputter, Sputter and then die.

This usually occurs when you are approaching a million dollar houseboat at high speed, and you are not sure that your liability insurance is up to date. Or when encountering an aircraft carrier on a collision heading. However, you might consider getting rid of the points, condenser, old spark plug wires and ancient coil. A nice new light chopper trigger and an electronic ignition may reduce the possiblility of an encounter of the worst kind. Even so, old dirty fuel and fouled carbs will still allow you, or your descendants, to call your attorney.
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