Electrical Issues.

[chargerdave]

Well, the sage continues. Replaced the distributor cap this evening, and still same result. Fire to the coil and a good spark at the points, but no fire at any of the plugs. Even tried trading out the rotor for a spare I had on hand but still no fire to plugs. About the only thing left to change is to assume that my coil wire is bad, even though its new, and replace it. Otherwise, i am out of answers. Anybody have any ideas? And, yes, in answer to the last poster, the distributor shaft and rotor are rotating just fine.

Edited April 27, 2012 by chargerdave

[JBNeal]

check the coil wire spark like a plug wire spark by holding the end near the block while engaging the starter motor with the ignition is on...if it ain't bluish white but more of a yellow, then the ignition coil may be the culprit.

[chargerdave]

Hold the distributor end of the coil wire up to the block? or the coil end of the wire up to the block?

[JBNeal]

the coil wire connected to the coil, disconnected from the distributor cap, and held close to the block should let the coil's secondary voltage arc to ground at the block. Jumper cables attached to the block and the battery ground can help with ground continuity for testing purposes.

[chargerdave]

Already have a heavy ground strap from the block to the firewall.

[Dave72dt]

did the points make the sparks when turning the engione over with the starter? If not, you still have some work to do on the primary, but you're close. Coil or coil wire is next. Switch coil wires and check for spark to the block. Sometimes the coil wire isn't fully seated in the coil and will fail to arc to ground.

[chargerdave]

Well, took the coil wire loose at the distributor cap and arc it to the block. It sparked well to the block, but still no fire to the plugs. Then I took off the distributor cap, turned the engine over and had a good steady spark at the points as they opened. So, I still don't know why no fire to the plugs.

Edited May 4, 2012 by chargerdave

[Young Ed]

Sounds like you might have a bad rotor/cap combination. Did you make sure you bought the proper ones for your dist number?

[Dave72dt]

You know for sure the primary system is OK and most of the secondary. As Ed said, cap and rotor may now be the culprit. They need to match the distributor. Center pin in the cap needs to contact the metal tab on the rotor so some measuring may be in order. Center pin in the cap? Sometimes they fall out.

[chargerdave]

Cap and rotor do match and the center post and spring are in the distributor. The cap and rotor are exactly like the ones that come with the distributor. I am now getting a very weak spark at the #1 plug when I ground it against the head and turn the engine over. There is a spark but it seems weak.

[JBNeal]

take some jumper cables and ground the spark plug directly to your battery ground and see if the spark changes intensity. If it gets more intense, your engine head isn't grounded properly, possibly from rusty threads at the head bolts and block.

[chargerdave]

Attached another ground strap from the head to the cab, but still too weak of a spark at the plugs for it to try and fire.

[Jeff Balazs]

ChargerDave;

I would try replacing the coil.....sounds like it is producing a spark that is breaking down to me. I have seen this a few times.

Hope this helps,

Jeff

[chargerdave]

have already tried two different 12V coils that require external resisted coils on it with the same results. The one on it now is a universal Accel Super Coil. I do also have an internally resisted coil that I haven't tried yet but not sure how to wire it up, since it has two posts on each side. (Two on pos. side, two on neg. side.).

[Jeff Balazs]

chargerdave;

Well then it is probably not the coil.

You do know it is likely going to be a "gotcha" thing.....like a bad piece of wire or a faulty connection.

I am curious though....did you actually try running a jumper directly from the battery to the head to make certain it is not a grounding issue? I learned a long time ago that you can never take ground for granted.

Keep at it.

Jeff

[chargerdave]

Connected a jumper cable from negative battery post to head, but still not enough fire to start or even to try and hit. Going back to my body work for a while and walk away from the starting issue for a few days, before it drives me crazy.

[Dave72dt]

One more thing to try before throwing in the towel. Bypass the resistor and check the spark. You won't hurt anything while in a testing mode. Just don't leave the key of for longer than you need.

[chargerdave]

Have been doing that for a while now. Still no difference

[Dave72dt]

battery is 12V neg ground and coil has neg post going to points if I recall. 3 new coils including one of those Accel super sparks. Any place you can have the coils tested? Can you swap the coils onto something you know has good spark and compare?

If they spark good on another system, the only thing I can think of is a weak condenser, be it new or not, that doesn't unload fast enough or is leaking down.

Edited May 10, 2012 by Dave72dt