Engine idling fine then shut off like turning key off, will not restart

[Bryan Howell]

This is also posted in Troubleshooting, but since I am [pretty sure my problem is ignition, not fuel, related I thought I would put it over here as well.



For long time forum folks, thanks for the years of advice and help. Happily, I finally got my A4 running great, two days ago. The surging issue resolved itself, magically, and the engine was running perfectly. Two days ago. Today, after repairing the genoa I went down to the boat, put the sail back up and went to start the engine. A little cranky but it started and was idling at the slip just fine. Started casting off lines to head out and poof, the engine just went dead, just like I had turned it off. Trying to restart met with zero success, even with ether, nothing, so I am definitely thinking ignition, not fuel. Checked spark at plugs and it seemed weak, checked spark from coil wire and altho a bit stronger still seemed weak. Tried cleaning and resetting the coil wire, nothing. The engine makes zero effort to start. The coil is virtually brand new after replacing late last year (thanks for the advice on that). Electronic ignition. New carb, fuel line, and tank (the root cause of many problems, a totally rusted tank). This is just infuriating, the engine was running better than it ever had just 2 days ago. The abrupt shutdown seems that whatever is wrong is central to the entire engine, not just one plug, so there are not that many things it could be. Could it be the distributor cap? A component in the electronic ignition (I don't know much about this part)? Plug/coil wire(s)? This is a pretty simple engine, why does it seem to confound so many of us so often???? Appreciate your thoughts.

[ndutton]

This is a pretty simple engine, why does it seem to confound so many of us so often????

Because this is an old school engine and old school wrenching/troubleshooting has become a lost art. This forum has a wealth of experience and information available to anyone for the asking but it will do no good unless the advice offered is followed.

I'll bet there are quite a few of us who went to the high school prom with grease under their fingernails.

[Bryan Howell]

Right you are

You have certainly given me a lot of good advice over the years, Neil. Do you have any magical insight s to the likely cause of this most recent really irritating problem?

[ndutton]

Do you have any magical insight s to the likely cause of this most recent really irritating problem?

Do we know - - not guess or believe but KNOW if this is fuel or spark related? Have there been any basic tests performed?

Spark:
Thatch keeps an old spark plug laying on the head at the alternator/lifting eye bracket. Pulling a plug wire off of a spark plug and plugging it onto the spare is an easy test for spark and all the parts are at your fingertips. The test plug laying on the head is sufficient ground for the test.

Fuel:
Is there fuel inside the carburetor? Remove the main passage plug with a catchment underneath and see if fuel comes out.

These are the most basic and simple tests, not intended for an AHA! moment but to point the troubleshooting in the right direction.

[Bryan Howell]

Do we know - - not guess or believe but KNOW if this is fuel or spark related? Have there been any basic tests performed?

Spark:
Thatch keeps an old spark plug laying on the head at the alternator/lifting eye bracket. Pulling a plug wire off of a spark plug and plugging it onto the spare is an easy test for spark and all the parts are at your fingertips. Laying on the head is sufficient ground for the test.

Fuel:
Is there fuel inside the carburetor? Remove the main passage plug with a catchment underneath and see if fuel comes out.

These are the most basic and simple tests, not intended for an AHA! moment but to point the troubleshooting in the right direction.

Neil:

Pulled two plugs to check spark, weak but a spark. Also tried the coil wire, a bit better but still not what I would expect. Fuel pump is pumping fuel, disconnected fuel line into carb and caught fuel being pumped out of fuel pump. The card has maybe 3 hours on it since I completely cleaned it, and it is brand new anyway. I would expect if it was fuel related some missing, sputtering, etc right before it died, not a clean now it is on, now it is off deal like I had. Something so abrupt is, in my experience, usually ignition related.
Sadly ignition is kind of my weak spot as a mechanic.

[ndutton]

Pulled two plugs to check spark, weak but a spark. Also tried the coil wire, a bit better but still not what I would expect.

OK, we have spark. Maybe not great spark but spark.

Fuel pump is pumping fuel, disconnected fuel line into carb and caught fuel being pumped out of fuel pump.

Fuel delivery is confirmed.

The carb has maybe 3 hours on it since I completely cleaned it, and it is brand new anyway.

This is not evidence. Give a brand new carb rancid fuel and you're right back where you started.

I would expect if it was fuel related some missing, sputtering, etc right before it died, not a clean now it is on, now it is off deal like I had. Something so abrupt is, in my experience, usually ignition related.

We have no real evidence it is ignition related other than your expectations and what you think it usually is. That is not evidence and therefore not troubleshooting.

Sadly ignition is kind of my weak spot as a mechanic.

Don't be intimidated. This forum knows ignition dead bang so no worries. The same troubleshooting principles apply to ignition as anything else but at this time we are not directed there. We may be later, just not right now based on what is KNOWN.

Given what we KNOW (spark and fuel delivery confirmed), this suggests a carburetor issue. I recommend a full carburetor disassembly and clean up paying attention to all components as long as it's open such as choke plate fully closing, all ports rooted out, float level check, debris in the float chamber, float valve not stuck closed, etc. I would also draw off a cup or two of fuel downstream of the pump, put it in a glass container and look for debris, water and/or phase separation. Make it as good as it can be, reassemble and try to start.

[Bryan Howell]

OK, we have spark. Maybe not great spark but spark.

Fuel delivery is confirmed.

This is not evidence. Give a brand new carb rancid fuel and you're right back where you started.

We have no real evidence it is ignition related other than your expectations and what you think it usually is. That is not evidence and therefore not troubleshooting.

Don't be intimidated. This forum knows ignition dead bang so no worries. The same troubleshooting principles apply to ignition as anything else but at this time we are not directed there. We may be later, just not right now based on what is KNOWN.

Given what we KNOW (spark and fuel delivery confirmed), this suggests a carburetor issue. I recommend a full carburetor disassembly and clean up paying attention to all components as long as it's open such as choke plate fully closing, all ports rooted out, float level check, debris in the float chamber, float valve not stuck closed, etc. I would also draw off a cup or two of fuel downstream of the pump, put it in a glass container and look for debris, water and/or phase separation. Make it as good as it can be, reassemble and try to start.

Well, Neil, yeh, I hear you, but....

The fuel, put into a brand new fuel tank 6-8 weeks ago from my marina's fuel dock 6-8 weeks ago, treated with Stabil, has run the engine just fine ever since, as it has with every other boat in my marina. The fuel is running thru new fuel line installed about 6-8 weeks ago, thru a new 6-8 weeks old water/fuel seperator/filter and a new -8 weeks inline fuel filter. The carb I took totally apart and cleaned every part of it 6-8 weeks ago, jets included, after I determined that the source of my engine woes was my old, original (78 Ericson) rusty, crud filled, water intrusion allowing gas tank. I finally confirmed that as the source when I decided to "draw off a cup or two of fuel downstream of the pump, put it in a glass container and look for debris, water and/or phase separation. " So after spending a huge amount of time and money, I fell fairly certain that my issue is NOT fuel related. Could be wrong. But there is some evidence, and experience, to support my position, and with most cases I have had in my career, circumstantial evidence is just as compelling as direct evidence, and here there is simply no way to definitively determine if it is fuel or ignition. But based upon living with my boat, and its issues, the very last thing I think it is would be the carb. Factor in that it does nothing with squirts of starting ether, and that the spark I observed seemed inadequate, if we have to start with an assumption, which we do, then I am going to assume it is ignition. Which is why I put this over on the ignition forum. Which is why I would love to benefit from the fact that "This forum knows ignition dead bang so no worries". I am not worried, I am just tired of this engine constantly having an issue. I do not have a sailboat to sit at the dock and work on it constantly.

So, if you, or anyone else, can provide me some advice, much as you did with your excellent advice here, Neil, only focused on the ignition, I would greatly appreciate it. And if I chase my tail fixing ignition issues and it still doesn't work, I will take the carb off and clean it.

[ndutton]

You solicited my advice and I responded with the best I could offer. In the end as always it's your boat and your choice. I wish you the best of luck.

[Bryan Howell]

You solicited my advice and I responded with the best I could offer. In the end as always it's your boat and your choice. I wish you the best of luck.

No, Neil, frankly I don't think you do. Why are you so dead set pre-determined that the problem is fuel, and specifically carb, related? Is it not at least as possible that it is ignition related? And if so, and if you are knowledgeable with the ignition system, which I have admitted I am not, why do you decline to offer any input on the possible ignition issues? Instead, you basically blow me off because I have decided to pursue ignition first because since it IS my boat, and I have experience with my boat, which leads me to think it more likely to be ignition? I am not disrespecting you, I just disagree, but even then it is not a strong disagreement, I just think it more likely than not to be ignition, based upon all of the facts related to my boat. Seems like in the spirit of this forum that I have experienced before that you would say ""ok, I think you are barkng up the wrong tree, but check this on ignition".. Instead yoiu wish me ""good luck"..disappointed, frankly. Oh well, whatever. Thanks for the advice, anyway.

[ndutton]

I'm not dead set it's fuel at all. At this point I'm following the information you provided and it suggests to me a fuel issue for the reasons I listed clearly. It may turn out to be just that or it may not, I can't say with certainty.

However, if you want to continue to track down ignition possibilities when it has already been established there is spark, that's your prerogative.

Like I said, I offered my best response and tried to explain it every step of the way. What you do with it is up to you. There are excellent diagnosticians on this forum, maybe they'll step up with different opinions. The goal is for you to resolve the issue to have a reliable engine by whatever means and to that end I do wish you luck.

[Bryan Howell]

I'm not dead set it's fuel at all. At this point I'm following the information you provided and it suggests to me a fuel issue for the reasons I listed clearly. It may turn out to be just that or it may not, I can't say with certainty.

However, if you want to continue to track down ignition possibilities when it has already been established there is spark, that's your prerogative.

Like I said, I offered my best response and tried to explain it every step of the way. What you do with it is up to you. There are excellent diagnosticians on this forum, maybe they'll step up with different opinions. The goal is for you to resolve the issue to have a reliable engine by whatever means and to that end I do wish you luck.

Ok, great, thanks. I appreciate your input and well wishes.

[tenders]

FWIW I happen to agree with Neil. Either you are systematic about this or you are just guessing, and guessing hasn't been working but he wished you luck, which is what it takes for guessing to succeed. You have spark. Move on. Next step is fuel. You have fuel. Next step is carb. If you don't want to check the carb now, fine, then check compression. But a sudden loss of compression at idle is not the more likely explanation of the symptoms.

I hear ya on the frustration of having to take a new carb off/apart. You paid to NOT have to worry about this stuff. But sometimes you do anyway.

[JOHN COOKSON]

Bryan
There are two parts to both the ignition system and the fuel system. The boat's part and the engines part. Which part of system is giving you the problem?
Sound trouble shooting practice is to bypass or confirm that the boat's part is not the problem then move to the engines's part of the system.
Ignition: Take a voltage reading a coil + when the key is in the on position.
Fuel: Put a fuel pressure gauge just before the carburetor and supply the fuel pump with clean fuel from an auxiliary tank.
After you have done these steps report back and we will tell you what to do next.

TRUE GRIT

[roadnsky]

...The surging issue resolved itself, magically, and the engine was running perfectly.

Bryan-
That sentence says a lot IMHO...
If it were my vessel, I would want to KNOW why an issue was resolved.

I took a bit of time and read thru your past threads and posts to get a better feel for the history leading to where you are today...

http://www.moyermarineforum.com/forums/showthread.php?t=10183

No resolution

http://www.moyermarineforum.com/forums/showthread.php?t=10263

Scavenge Tube & Carb issue

http://www.moyermarineforum.com/forums/showthread.php?t=10493

Resolution? No answer to carb question in POST #15

Something that really stands out, that I agree we should resolve BEFORE moving on to the next "step"... (IGNITION) is to assure that we can eliminate fuel.

We need Fuel, Spark and Compression to run our beasts.

Here is one of my favorite Don troubleshooting methods...
“Have you performed any maintenance on the engine recently?”
It always provides me with a bit of tension releasing amusement when I'm told: "Why yes, I just replaced the plugs, points, and condenser last week, - so I know that the problem can't be in that area!" (Not necessarily so)! Whenever you experience problems after performing maintenance, always go back over every step of your work to see if you overlooked something.
This is one of the most fertile places to find reasons for intermittent shutdowns.

Attached is a document with some more of Don's troubleshooting wisdom.

[Bryan Howell]

Bryan
There are two parts to both the ignition system and the fuel system. The boat's part and the engines part. Which part of system is giving you the problem?
Sound trouble shooting practice is to bypass or confirm that the boat's part is not the problem then move to the engines's part of the system.
Ignition: Take a voltage reading a coil + when the key is in the on position.
Fuel: Put a fuel pressure gauge just before the carburetor and supply the fuel pump with clean fuel from an auxiliary tank.
After you have done these steps report back and we will tell you what to do next.

TRUE GRIT

Great, thanks John. Will do and will report back.