Troubleshooting No Spark

[rpowers]

Hi freinds,

The engine wouldn't start last weekend after a nice sail on the SF bay. Luckily we were able to sail right into the slip, under control with little effort.

We had motored out with great performance and a good sounding engine.

So now I am troubleshooting.

Compression? check.

Fuel? Plenty out of the pump. Carb area gets fuel smell fumes.

Ignition? There lies the problem.

Plugs don't spark out of the cylinders while grounded.

OK, so I started working the problem, but need your help please.

I have a multimeter, and can measure 12V going to the coil. With the ignition switch "on", Both positive and negative terminals have 12V when connected to ground. The central post on the coil also shows 12V.

How many volts should that center post read with the ignition "on"?

I tried the called-for experiment of arcing the coil central wire to the cylinder block, but saw no spark.

So I replaced the coil with a new one, and still no big spark.

I checked the connectivity of the coil wires (and also the 4 plug wires) and my multimeter could not detect connectivity on ANY of the wires.

Is that possible, or do they have too much resistance for a multimeter to connect through them?

Help, I am stuck!

(PS- From Ken at MMI I have coming tomorrow a new set of wires and new rotor head.)

[sastanley]

I am not very good at this part...there should be a resistance number for the spark plug wires that would indicate if they are OK. The coil should be producing a LOT of voltage thru these wires hence a visible spark when grounded. Even if the fittings are poor to the wire's core the engine may still run as they should arc over. Also, if you have 5 wires, it is unlikely they all go bad enough at once to cease engine operation.

I don't think you'll find the solution in the wires, although I'll also admit they were the 2nd thing I replaced on my A-4. I found the fitting on the coil side of the wire detached (although the engine still ran), and had no idea on the age/history of the wires.

[Baltimore Sailor]

Do you get a spark coming off the points? Here's Don explaining how to do that:

"The thing that you may be missing (at least in your report) is that you not only have to supply 12 volts to the positive terminal of the coil, you have to also switch the 12 volts on and off. The secondary voltage (approximately 24,000 volts) is delivered to the end of the coil lead at the instant you break the circuit through the coil. In the ignition system, the circuit to the coil is broken on the negative side by the points.

"The way I like to check for coil function is to bump the starter until the points are definitely closed. Then, with the ignition switch on, I open and close the points using a pencil or small screwdriver. Each time the points open, I look for a good secondary discharge between the end of the coil lead and the top of the head."

Give that a try and see what you get.

[Rick_Powers]

I have the electronic points (rotating magnets).

[Baltimore Sailor]

Do you still have the old points? If so, put 'em back in and make the test. (I kept my old points and stuff around "just in case.") It sure sounds like you're having problems along those lines.

There might be a way to test with the electronic ignition in place, but I sure don't know what it would be.

[rpowers]

Hi Baltimore,

I bypassed the points issue completly by wiring a spark plug directly to the coil.

When I crank the engine I get no spark. So I replaced the coil. Still no spark.

I do have 12V going into the coil.

Arg! What is going on?

[rpowers]

What is the difference?

My coil is labeled for external resistor, but I think I don't have one...

Could that be a clue?

[Baltimore Sailor]

Have you seen this yet? Don explains it much better than I can:

http://www.moyermarine.com/forums/attachment.php?attachmentid=544&d=1210423270

[67c&ccorv]

What is the difference?

My coil is labeled for external resistor, but I think I don't have one...

Could that be a clue?

What kind of ignition system do you have and is it an early or late model A-4?:confused:

PS - this story sounds familiar Don!

[rpowers]

It is a late model engine, with the electronic points.

The short of the problem, is that even with a new coil, I can get 12 volts to the positive terminal, but yet cannot get a spark out of the top of the coil to ground.

I am perplexed!!!

[Don Moyer]

It's not enough to provide 12 volts to the positive terminal of the coil. In order to get a secondary discharge from the coil you will have to open and close the circuit to the primary windings (the positive and negative terminals). This switching function is done by the points (or an electronic switching module in an electonic ignition system) opening and closing the path to ground. Each time the swithing device opens the circuit, you should see a secondary discharge between the end of the coil lead and ground by holding the end of the wire 1/4" or so from the head.

Don

[rpowers]

OK, I'm going to swap back from the electronic ignition to my old points and condenser.

Although it seems unlikely that the electronic ignition would fail, that must be the case...

Will report back later...

[Rick_Powers]

Baltimore, you get the prize!

I switched back from the electronic ignition to my old points and condenser plate and viola', it started right up.

Although I was told that the electronic ignitions rarely fail, it failed on me.

Lesson learned: Always keep your old analog points on hand.

Thanks for the help.:)

Over and Out.

[rigspelt]

I switched back from the electronic ignition to my old points and condenser plate and viola', it started right up. Although I was told that the electronic ignitions rarely fail, it failed on me.
So, what caused a normally reliable part to fail? The wrong coil, over-volting the EIM, and ... what else?

[67c&ccorv]

So, what caused a normally reliable part to fail? The wrong coil, over-volting the EIM, and ... what else?

I am going to bet on wrong coil without the necessary 3 - 4 ohms resistance!;)

[Azul]

I would bet on the wrong coil as the cause of your spark failure. How long were you using the electronic ignition on your boat?