Just a couple of questions about coils

[a_kraker99]

Our old thread started by my brother HERE sort of died off. I think the post count scared everyone away. I just have a couple questions relating to coils....

We just replaced the power pack and realized the for some reason we had to reverse the DVA testing wires to get the correct reading on the orange wires to the coils. So the old one may or may not have been bad.

What we did find out was that there are 2 coils that will not jump a 7/16 air gap and 2 that will. 1 on each side of the engine so it doesn't have anything to do with the sensors. We also switched the power pack coil output wiring and put the coils on different plugs/cylinders to make sure it wasn't the power pack output or a bad plug causing the problem.

If you touch the top of the two bad coils while it is running you will get a poke. I would assume that is a bad sign right? What causes them to short out like that? Is there something we should look at to make sure new coils wont go bad too? Should we just replace the 2 or is it best to just replace them all at the same time?

 

[emdsapmgr]

Re: Just a couple of questions about coils

Would be helpful to know just what hp and year engine you are having problems with....

 

[tx1961whaler]

Re: Just a couple of questions about coils

Our old thread started by my brother HERE
"I have a 1974 135hp Evinrude. v4 "

Had to look at the old thread....

 

[fireman57]

Re: Just a couple of questions about coils

If you get a shock then they are arcing to ground most likely. You should be able to just replace those two coils. If you run it in the dark you will probably see a blue or yellow lightning strike going to the block.

 

[emdsapmgr]

Re: Just a couple of questions about coils

Make sure the ground surfaces are perfectly clean. Sometimes the grounds get aluminum oxide (or rust) on them with age and won't conduct current. It is a good idea to run the engine in the dark to visually check for spark jumps to ground. Spark plug coils are usually fairly reliable. Those coils don't have to be replaced in sets.

 

[a_kraker99]

Re: Just a couple of questions about coils

Thanks, we will check and clean the grounds first. The coils are fairly new so it seemed a little odd that they would go bad already. I didn't know if there was something else we should be looking at that might make them go bad.
I can't believe the oxidation could get so bad that the path of least resistance is through the coil itself.

 

[emdsapmgr]

Re: Just a couple of questions about coils

Have you tested the stator for voltage output? If a stator is weak, it may not always fire the coils.

 

[a_kraker99]

Re: Just a couple of questions about coils

Yup, Stator is fine and we have a new power pack which tested fine.

I just cleaned all the grounds and cut a little off both ends of the spark plug wires and reattached them. If I go from a 7/16 gap to a 5/16 gap I will get spark while the engine is running but only intermittently while cranking. The spark I get through the gap looks pretty weak though.

 

[AlTn]

Re: Just a couple of questions about coils

are you using the trouble shooting guide at cdielectronics.com?

 

[emdsapmgr]

Re: Just a couple of questions about coils

That engine's stator makes it's own voltage to fire the ignition. The starter must crank the flywheel between 200 and 250 rpm's in order to make enough voltage to fire all the coils/plugs. Make sure you are cranking with a strong battery and that the starter will rotate the flywheel fast enough.

 

[a_kraker99]

Re: Just a couple of questions about coils

Yes, my brother used that guide to test everything I believe.

The issue with the spark not jumping the gap at 7/16 is both while cranking and running. But it is only on 2 of the 4 cylinders.

We got new coils coming in tomorrow so we will see if thats the issue or not.