Coil problems

[blhickson]

Why does my coil go bad so fast? How long should a new one last? The PO had 2 used coils on board(as spares I guess?) but this one is only 6 months old and shows from 1.8 to 2.9 resistance. Is this an alternator prob and could it be related to fuel starvation shutdown issues? I've looked for arcing and cracks-nothing there. Any ideas? Coils are expensive!

[ndutton]

We need to know more before we can help. Can you tell us:

1. if you have electronic ignition?
2. the voltage between the small coil + post and the engine ground (NOT the other small coil post) when the engine is above 1000 RPM?
3. under what conditions you measure different resistances on the same coil?

With that information I bet we can solve this quickly.

edit: coil performance and fuel starvation are completely isolated from each other except for maybe a voltage issue supplying an electric fuel pump but that's really reaching.

[BunnyPlanet169]

Originally Posted by blhickson

The PO had 2 used coils on board(as spares I guess?)

Follow Neil on the coil troubleshooting - he's driven this topic and really sorted it out.

I keep a new spare, and my used coil is on the engine. I can't think of a good reason why I'd have spare 'used' coils, but a compulsive hoarder might keep a couple 'intermittent problem, but nearly as good as new' coils around. I'd consider them suspect at best.

[sastanley]

Originally Posted by BunnyPlanet169

but a compulsive hoarder might keep a couple 'intermittent problem, but nearly as good as new' coils around. I'd consider them suspect at best.

Hey, now...don't judge..

[blhickson]

Electornic ignition here. Should the resistance change with the rpms of the engine? I may not be using the voltmeter correctly. I found a new coil on board (from Indigo) and I tested its resistance (in hand) and it was the same poor 1.5 to 2.8 as the one mounted on the engine. ??? The alternator was tested and it read about 25, so not so good there. The alternator reads "Transpro" on the back. It looks old and the PO was definitely not into the engine work. Just sayin'. The contacts on the alternator to the fuse are corroded on the inside.
I'm taking both alternator and coil to a reliable car mechanic to see what he says about a bench test for both. The engine was very hard to start today as has been the case since the carb rebuild, but once started, she sounds good if the idle stays up. The choke does not seem to affect the starting at all, just the throttle. I'm concerned that the starter itself is compromised. Is that in line with what is going on? I tried to start 4 times and wouldn't start, then there was nothing. There seemed to be a "tiring" of the sound of ignition so I stopped and checked the batteries. Both read 12 v.
I'm trying to locate a remotely held tach to check the rpms but they seem to be for pro mechanics and digitial and very expensive and I cant pull the trigger on that. I'm not going to change anyting until I suss out the alternator/coil problem. I have always believed the misfiring of the engine was an ignition problem, not a fuel problem. I cleaned everything 6 months ago.

[blhickson]

Also, the engine DID start after several (6) tries with the throttle and no choke and stayed running unti I shut her down to remove alternator.

[blhickson]

And I have a mechanical fuel pump rebuilt in the last year and still intact seems to be working ok.

[BunnyPlanet169]

Originally Posted by blhickson

Also, the engine DID start after several (6) tries with the throttle and no choke and stayed running unti I shut her down to remove alternator.

Are you sure the choke is operating (especially since rebuild/reinstall)? It might be a good idea to take the flame arrestor off and look into the carb with a flashlight while someone moves the choke cable. The A4 has an 'updraft' carb design, pulling fuel up through the carb body into the manifold. It really prefers having the airflow choked to help get gas flowing, especially when cold. A lot of throttle has a similar result, but then will usually race to uncomfortably high RPM.

[ndutton]

Now that we know you have electronic ignition it's important you read this thread:
http://www.moyermarine.com/forums/showthread.php?t=5845
It's not the only thread on the subject but is sort of a Cliff Notes version.

[JOHN COOKSON]

Originally Posted by BunnyPlanet169

I keep a new spare, and my used coil is on the engine. I can't think of a good reason why I'd have spare 'used' coils, but a compulsive hoarder might keep a couple 'intermittent problem, but nearly as good as new' coils around. I'd consider them suspect at best.

+1
I'd consider them dead.
Coil heat damage is progressive. A heat damaged coil is no spare at all IMO.
Barbara is on the right track. Figure out what is causing coils to fail.

TRUE GRIT

[sastanley]

Barbara, You can get cheap photo sensor optical tachs now at places like Harbor Freight for about $40.

I think more important than a tach, would be a timing light. One symptom of timing being off a few degrees can be hard starting.

You have a lot of stuff going on at once..we really need to work on them one at a time.

I see there is another thread you started about carb work...multiple threads sometimes get confusing..that seems to be an older outdated thread now compared to this one.

I'd get the carb, fuel & choke under control first, and then move to the ignition. Jeff mentioned proper choke function. If choke position makes no difference when you try to start, it is NOT set correctly. It needs to be fully closed to start a cold A4 quickly. pull the flame arrestor and visually check.

[blhickson]

I will definately check the choke mechanism. I misunderstood the thread that says "always start with a closed choke." Normal operating is open and you close it "choke" it to start a cold engine. Now I get it. No wonder I smell gas so quickly! LOL and yes the blower is always on and I am very careful.
A guy at NAPA was kind enuf to let me borrow his digital multimeter and the present coil measures 4.2. Must have been operator error testing coil with analog voltmeter. The alternator needed a new voltage regulator. I will reinstall that tomorrow then I will visually check the choke. I'll find a timing light-out of curiosity, I moved the distributor back and forth to see what effect it would have so I'm sure the timing needs setting.
Thanks for the great advice.

[sastanley]

OK, Barbara, great. Making progress. Did you move the distributor around while the engine was running? If so, be sure to lock it down with the motor running the best, for now.

Yes, pulling the choke cable "closes" the choke, and allows less air into the motor, which helps it start when cold. I've found that about one hour or so after shut off, I can start without choke, but anymore than that, I need some choke to start, and fully closed choke when cold. Choke cable in = fully open..

4.2 Ω at the coil is good...the problem those of us around here have experienced with bad coils is when cool it is just fine and when it gets hot, we suspect one of those tiny little windings separates, and makes the ignition circuit fail..hence the discussion that once a coil fails once, it is toast...Once it cools off, the skinny wires reconnect and the process repeats. let's hope the resistance at the coil is still 4.2Ω after running for an hour or more.

Again..one thing at a time...but good data on the coil & alternator.

[JOHN COOKSON]

Originally Posted by blhickson

Must have been operator error testing coil with analog voltmeter.
.

Maybe a weak battery. Try a new battery in the meter.

TRUE GRIT

[Rbyham]

Haven't seen the other basic warning that is part of these discussions. If cranking a non starting engine be sure and close raw water intake if RWC... Look at me giving advice... Woohoo! ☺

[Golfdad75]

Ken at Moyer Marine recommends a coil between 3.5 and 4.5, perfect would be 4.
I am putting in the PerTronix electronic ignition and they recommend the Flamethrower Coil which is rated at 3.0.

Ken has not ever let me down, however the Pertronix is in the business and they made the system.
Any suggestions

[edwardc]

Add the extra 1 Ohm resistor. You'll be happy you did.

[sastanley]

GolfDad, Ed gave you the short answer, which is perfectly acceptable.

Another alternative is to buy one of the coils that Moyer sells...it is in the range you are looking for.

If you REALLY want to understand it..read this thread, below.

www.moyermarine.com/forums/showthread.php?t=5748

[Golfdad75]

The people at Moyer Marine are so friendly that I hate not to buy from them. I ordered the coil yesterday.
Two weeks ago I knew nothing about coils.

[ndutton]

Originally Posted by Golfdad75

Two weeks ago I knew nothing about coils.

And in time you'll be better versed on the intricacies of the Atomic 4 than the vast majority of professional marine mechanics out there.

[hcrisp]

All too true, Niel. I was just advised by a mechanic that no fuse was necessary if any wire run was shorter than one foot. Egad! Similar experience last week with the manager of the local WestMarine.
Important to stay connected with this forum.
Howard

[ndutton]

Originally Posted by hcrisp

I was just advised by a mechanic that no fuse was necessary if any wire run was shorter than one foot. Egad! Similar experience last week with the manager of the local WestMarine.

The ABYC allows a length of unprotected (unfused) wiring and depending on certain conditions the length can be 7, 40 or 72 inches. The basic allowance is 7 inches. I believe their reasoning is, "What can go wrong in 7 inches?" (plenty if you ask me). In non-authoritative, seat of the pants, common sense application, unprotected wiring is bad practice period. For Mr. Mechanic, his distance is wrong and his suggestion fusing is unnecessary, unsafe.

As an example of official standards that are often eschewed, the National Electric Code allows wiring of different voltage systems to be placed in the same conduits and junction boxes provided the wire rating meets the highest voltage present. No responsible electrician does that however. 120/208 voltage systems are completely separated from 277/480 systems with their own conduits and boxes. Point being although allowed, true craftsman apply a higher standard. Same with the fusing discussion and the ABYC.

Speaking of "experts", you ought to hear some of the Shinola dispensed by the experts wearing orange aprons in the Home Depot electrical department. Someday they'll kill someone if they haven't already.

[roadnsky]

Originally Posted by ndutton

As an example of official standards that are often eschewed, the National Electric Code allows wiring of different voltage systems to be placed in the same conduits and junction boxes provided the wire rating meets the highest voltage present. No responsible electrician does that however. 120/208 voltage systems are completely separated from 277/480 systems with their own conduits and boxes. Point being although allowed, true craftsman apply a higher standard. Same with the fusing discussion and the ABYC.

A Gold Star for Neil for proper (and timely) use of expanded vocabulary.

[ndutton]

That word was branded on my brain a few years ago on this forum, took me out of the running for a free set of spark plugs too. I could have eschewed "eschew" but my strategy is if I use it enough it will become ubiquitous and hopefully level the playing field next time.

Originally Posted by Golfdad75

Ken at Moyer Marine recommends a coil between 3.5 and 4.5, perfect would be 4.
I am putting in the PerTronix electronic ignition and they recommend the Flamethrower Coil which is rated at 3.0.

Ken has not ever let me down, however Pertronix is in the business and they made the system.
Any suggestions

This is from post #179 of the "Coil Input Information" thread. The basis of the math is Pertronix's own advisement, buried deep in their literature, of a 4 amp system maximum.

If all of us who made the move to EI had only followed Don's advice from February 2005 of a 4 ohm coil, none of this would have happened. None of it.

I used a 3 ohm coil. After all, Pertronix - whose name is on the EI unit - said their coil (3 ohm) was the perfect match to their EI system. Well, it ain't. The math works out at 12 volts but once you consider alternator voltage when the engine is running - somewhere between 13.8 and 14 + volts (less system voltage drop), their math flies out the window.

Using a coil or coil and resistor combination of 4 ohms protects the EI system up to 16 volts. Pertronix won't tell you that (why I don't know) but Don did nearly seven years ago.

The math or alternatively the provided resistor calculator varies because all of us have different voltages at the coil due to differences in wiring systems and their resultant voltage drop and differences in alternator output voltages (the manually adjustable crowd often being the worst offenders). The 4 ohm coil figure works well for those who flunked math.

[warefuller]

Almost all coils are 6-volt coils - they have a low impedance (resistance). If they are run at 12-volts they will get quite hot and eventually fail. Either use a high-resistance coil or add an external resistance (auto parts store) in series with the coil. An even better choice (with a 6-volt coil) is to wire the coil so that it gets 12 volts when the ignition switch is in 'start', and 6 volts when in 'run'.

Ware

(without a silly quotation)