Nissan CDI failure mode?

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km1125

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I have an NSF-5B that was converted to 6HP with a carb. It has been running flawlessly for a year.

Was running it over the weekend and after about 15 minutes of almost full throttle (about 5200 RPM) I noticed it miss a couple times. A few minutes later it started losing power. We were almost at the destination, so I dropped down to about 3000 and ran for another 3-4 min, then when down to just over idle as we were approaching the anchorage. Before we got there, the engine quit. It stumbled a couple times just before it quit. I tried to restart and noticed the oil lamp blinking crazy, so I thought I might actually be low on oil... as I hadn't put any in for months (didn't seem like it ever needed it). It was low on the dipstick, so I put a little in, but being careful to NOT overfill per Paul's previous guidance on here. Ran it again on the way back, but due to lake conditions didn't go as fast. As we were approaching the marina I noticed a few more misses, but it made it back to the dock ok. It was one of the hottest days we've had this year.... ~90.

Today I took it out on the lake today (and it was hot again). I ran it back and forth for a bit and started to notice an occasional miss but also a hesitation at mid-throttle when throttling up. Took a while but it finally died. As it was dying, I was careful to observe the oil light and it DID NOT light at all. When I tried to pull-start right away, the oil light was blinking like mad, just like the day before. I popped the top and checked over everything and nothing seemed amiss. The coil and CDI were hot, but not more than you'd expect being connected to the block or 1" from the head. I had a cup handy, so I poured some lake water over both for a minute or so. Pulled the cord and it started up. Ran around again till it stopped and repeated the exercise and it started up again. The oil light was not blinking or lit before it died, but blinking when I tried to pullstart right away.

If I was foaming the oil, wouldn't the low oil pressure light blink before the engine would die?

Is it possible the oil pressure switch is bad? This would make sense for the blinking light when trying to start, but does not explain why it dies in the first place. I didn't think of it while I was out there, but I should have disco'd the oil switch wire and tried to start it.

I'm wondering if it's a heat-related CDI issue, but I'm not familiar with different CDI failure modes. Is this something that anyone has seen before? However, since the oil light is blinking, I don't know how that could happen without the oil switch making contact.

Suggestions? I do have the real service manual and can do all the resistance checks but wonder if this would show anything unless the CDI is heated to temperature. This unit has the exciter coil and pulser coils, and I can check those too (but have the same heat-related concern).
 

Sea Rider

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For a starter install a new spark plug well gaped and check OB behaviour . Don't know if a bad oil switch will account for those symptoms. When dealing with electrical components behaviors there's 3 conditions : Good, Kaputt or Intermitent, being the latter the most PITA to troubleshoot and diagnose properly.

When cold electric components works well, when internally heated OB starts to miss, when cools down will work ok momentarily till heats up again, a never ending repetitive issue. When measured cold will be Ok, the issue is measuring them when heated up and missing while OB sits at back transom.

Have learned that the fastest way to find the culprit is swapping new for previous electrical components which have in stock. Plan to keep my OB for a looong time, but that's me...

Happy Boating
 

pvanv

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Luis is correct that troubleshooting bad electronics that are intermittent will test your patience. The oil lamp is working properly; It should be OFF when at pressure, and always blinks when pull starting, so that's OK.

Your issue could be anything from an overheating CD to a chunk of crud in the carb to who knows. I would try running with the cowl off to get a little cooler, and see whether you still have problems. If you do, then if thinking it's electrical (pull the plug, and if wet, there's no spark), test when hot. Having a spare exciter and pulser (about $30 each MSRP) might be money well spent as these items may disappear from the shelves in future years.
 

km1125

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The oil lamp is working properly; It should be OFF when at pressure, and always blinks when pull starting, so that's OK.
That's why I elaborated a bit on the light. I do always see it blink just A LITTLE when I pull start, but when this is acting up, it is blinking A LOT when I pull start.

I don't know if it's coincidental or not, but I had just added a tach that day. It's a KEDSUM, the kind that wraps around the coil wire to sense the spark. I have since removed it but it got me thinking... I wonder if there is some impact when you wrap that lead wire around the coil wire... it's acting as a slight choke to the spark current and if something like that could affect a CDI by adding some type of 'back EMF' into the primary side of the coil... not unlike just leaving the coil wire unplugged when you're cranking the engine.
 

Sea Rider

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Installing induction tachs pick-up wire wrapped 2-3 turns on any of both spark plugs cable won't interfere with anything electrical or mechanical related. Just curious, are all grounds and electrical components contacts in well cleaned and shinny cond ? Seen some electrical components contacts fail due to rusty conditions which can heat up and even short any component.

If oil amount is adequate and oil light goes off when OB has started nothing to worry about. Get a Spark Indicator (Lisle) has some nice ones and check spark strength, but will not indicate which electrical component is intermittent if that were the case..

Do you know of anybody that will lend momentarily a CDI or a Ignition Coil to test on your OB. Pulser and Exciter Coils usually don't go bad.

Happy Boating
 

km1125

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Just curious, are all grounds and electrical components contacts in well cleaned and shinny cond ?
The engine and connections are "showroom clean".

If oil amount is adequate and oil light goes off when OB has started nothing to worry about.
Once running, there is no issue with the oil light. Only when attempting to restart after it has quit does this become a concern and it exhibits a different behaviour than when normally starting it.

Do you know of anybody that will lend momentarily a CDI or a Ignition Coil to test on your OB. Pulser and Exciter Coils usually don't go bad.
Last year I had another motor (4A that I converted to 5HP) that I could have used as a 'parts loaner'... but I sold it! ARRGH! :)
 

Sea Rider

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Minimum investment, check running cond with a new spark plug gaped to specs, see what happens..

Happy Boating
 

km1125

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Still haven't resolved this issue but very strongly suspect the CD unit. I done many tests and could easily reproduce the issue and when I cool the CD with a cup of water, everything works OK. This is also the same CD unit that I had in a different thread where I measured the timing and it was always at -25 degrees, whereas the manual said it should be at 0 degrees at low RPMs and 25 degrees at high RPMs. I could never confirm if those specs applied to ALL revisions or just certain ones. If it was supposed to apply to ALL CD units, that could have been an early indication of a failure.

However, my question NOW is "when did they make the change from having the separate exciter and pulsar coils to an integrated unit?" Mine has the separate coils and I'm guessing that the ones with the integrated coils use a different CD. Just want to make sure when I'm looking at used replacements (if I can find one) that I'm looking at the right one.

OR, maybe a different question: Could I use a 3GR-06041-0 integrated unit if I wanted to pull the flywheel and install it in place of the existing exciter (or does it go in place of the pulsar?) Is the machining in the block the same and is the flywheel the same?
 
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km1125

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OK, I might have answered my own question. I started going through the various parts books for the various models, and it looks like in the "B" series 4/5/6B they had an "old" and "new" ignition. The "new" used an integrated part. The "old" used the same non-integrated parts of the "A" series. Then it looks like they changed the part for the "C" series.

That didn't quite answer my question regarding if the block machining allows to you interchange the parts though. Will a 5C integrated module fit on a 5B block? Seems like if they used both systems on the 5B model that it would. I don't know if I'd go that way, but it would give me an option.

Checking the parts list also gave me questions about the flywheels. There appear to be three... the 3R1060010 that comes with the 5A and prior, then they switched to either a Mark 48 or Mark 50 for the 5B and newer. It appears that you need the Mark 50 if you have an alternator on the 5B and 5C. I did buy an alternator to put on my motor (the 399060231) and it looks like that will work with the original 3R1060010 flywheel that I have.

It looks like the flywheels are all interchangeable in terms of ignition, but if you need the newer alternator (higher output?) then you need the Mark 50. Does that sound correct?
 

Sea Rider

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Sorry, usually like replacing the exact model part that corresponds..Paul should know about that...

Happy Boating
 

pvanv

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If it works when you cool it with lake water, but fails hot, it sounds like you have diagnosed a thermal-failing CD. Yes, the newer 1-piece ignitor will work electrically, but the early blocks don't have the provision for mounting it. Best way to go, again assuming that you have a failing CD, is to just replace it. I don't have any used ones in the shop. There were two different versions, depending on serial number. The very early model unit was revised for better performance. All that is available now is the better unit. For SN 020184XE and below, the part you will want is:
3R1060601MC.D. IGNITION UNIT (CU2568) NEW STYLE$131.17
 

km1125

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If it works when you cool it with lake water, but fails hot, it sounds like you have diagnosed a thermal-failing CD. Yes, the newer 1-piece ignitor will work electrically, but the early blocks don't have the provision for mounting it. Best way to go, again assuming that you have a failing CD, is to just replace it. I don't have any used ones in the shop. There were two different versions, depending on serial number. The very early model unit was revised for better performance. All that is available now is the better unit. For SN 020184XE and below, the part you will want is:
3R1060601MC.D. IGNITION UNIT (CU2568) NEW STYLE$131.17

OK, I'm done having fun playing it and have decided to replace it. It's pretty predictable in the failure mode, but I'm sure some day it will get worse... or I'll really need it when it decides it's too tired!

Paul, I sent you a PM for contact info... do you have one in stock?
 

pvanv

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I can send you one in 2 days. I've replied to your PM. Darned system doesn't tell me when I have a PM...
 

GA_Boater

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Done deal and too open for this forum.

Look for a red number by your username if you have PM notifications turned on.

Closed.
 
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