No spark, need help......

[JTB321]

OK, I'm having a huge problem solving this no spark problem. But I'll not bore you with all the previous fault finding but say I have replaced the TFI, distributor is new, coil is new and wiring point to point checked, and a re-manufactured EEC IV installed.

So back to basics and check that the coil would spark off the car. With the connections below what do you think momentary connection of the black wire to battery negative would do?
Just for clarification the red lead is to the coil + and the black is switching the coil - to 0V.



I was expecting a nice fat spark but no? Tried the original coil, no spark and even checked with another new coil, still no spark?

What am I missing, this problem is a PITA

Could someone please replicate this set up in their garage and let me know what happens?

John

[Excaliber]

The basic wiring looks like it should work. Assuming... The positive wire resting on the top of the pos terminal of the battery is actually getting a good connection, it doesn't look like a good connection. Did you use a meter to verify 12 volts at the two coil terminals?

If so, then a sharp and sudden break of the negative connection at the battery terminal should result in spark.

[Rick Parker]

Doesn't the missing module step up the primary voltage, I believe so.

[Excaliber]

If I recall the MSD module's step up in the neighborhood of 400 volts, so it's a good question Rick.

That would be: Does THIS coil require the high primary voltage in order to fire?

[Excaliber]

Uh oh, it just dawned on me that many of todays modern coils work fine with a module but will BURN UP if you use 12 volts direct to the primary circuit. Many of them REQUIRE a ballast resistor that drops the 12 volts to about 6 (7 or 8 maybe).

It's possible the coils that have been tested with the above wiring schematic are now toast.

[JTB321]

Thanks guys but the coil wiring for the Mustang does not include a ballast resistor.
The circuit does have good connections, the photo is just to show the configuration.
No spark, engine not run, no complete project......running out of ideas...

[Excaliber]

Very few cars, these days DO include a ballast resistor. It's function is handled by an electronic type ignition control module. But what your doing is like an old school point and condensor type wiring, no electronics, just wired straight to the battery with the negative wire acting, as it were, "the points". A mechanical switch that makes or breaks the current, with a condensor that helps to limit arcing across the point contacts which would lead to burned and pitted contacts.

SOME coil's have an INTERNAL ballast resistor, some require an external one. Often, with todays modern coils designed to work with electronics, they do not have nor require an INTERNAL resistor. A resister can be purchased from any neighborhood parts store. They all serve the same basic function, reducing the voltage from 12 to 6 or 7 volts. It really doesn't matter what vehicle you have, if it came with points, it had a resistor OR (like GM) a resistor WIRE included in the wiring harness.

12 volts to a coil without a resistor will burn up the primary wiring inside the coil, you will not see the damage.

[Murky781]

Adding to this thread because I have NO SPARK. 69' 428, MSD-6AL, replaced coil, voltage reg. ignition switch. Did the paper clip test on the MSD, it was good. Car turns over quickly, but will not fire. Screwdriver in coil wire doesn't spark. Dist. is turning, rotor looks good, not carbon trails in cap. Battery fully charged and grounds checked.
Car ran great, then was hard to start, (20 secs. cranking) turned it off, then 40 sec cranking. one last start of close to a minute cranking, got it home and it will not spark now. I'm open to help, dash is out and i have power to ign. switch with power on and cranking. Beautiful day and I'm stuck!!! thanks guys
It's an ERA if that makes any difference

[davecobra]

I had a msd pickup coil in the dist go bad and that is how it acted, paper clip test said box was okay, but the pickup coil in the dist failed, replaced it and it worked. For the record it started to act up several days earlier, would be very hard to start, had to crank and crank and finally it would start, then it left me stranded at the store, no spark, had to tow it home, took a week for me to find the problem. Hope that helps.
David

[patrickt]

Originally Posted by Murky781

Adding to this thread because I have NO SPARK. 69' 428, MSD-6AL, replaced coil, voltage reg. ignition switch. Did the paper clip test on the MSD, it was good.

When you do this, what is the result? Do you get a spark to ground?

1. Make sure the ignition switch is in the “Off” position.
2. Remove the coil wire from the distributor cap and set the terminal approximately 1/2" from ground.
3. Disconnect the MSD magnetic pickup wires from the distributor.
4. Turn the ignition to the On position. Do not crank the engine.
5. With a small jumper wire, short the MSD’s Green and Violet magnetic pickup wires together several times. Each time you break this short, a spark should jump from the coil wire to ground.

[Murky781]

To Dave... that's what went on with this. Haven't checked that yet..any easy way to do it? Patrick..I did that and I get a good spark to ground. I'm just lost as where to go. No spark from coil wire to ground by cranking.
thanks

[patrickt]

Originally Posted by Murky781

Patrick..I did that and I get a good spark to ground. I'm just lost as where to go. No spark from coil wire to ground by cranking.
thanks

The the next step is to keep everything exactly the same and plug the magnetic pickup back in and crank it. If you see no spark going to ground while cranking then it is the magnetic pickup.

[Rick Parker]

One other item to mention, doesn't the coil frame require a ground also?

[Rick Parker]

Magnetic pickup ..........replace it, you have an open circuit

[Rick Parker]

When you are installing it, if you get the MSD OEM unit, they caution you as to the correct magnet orientation. Get it wrong and you will open another can of worms. Do NOT crack it either. Be careful of the wires being connected properly, it it easy to do it wrong .

[patrickt]

Originally Posted by Rick Parker

When you are installing it, if you get the MSD OEM unit, they caution you as to the correct magnet orientation. Get it wrong and you will open another can of worms. Do NOT crack it either. Be careful of the wires being connected properly, it it easy to do it wrong .

OK, in other words, "Don't put it in backwards, don't wire it up the wrong way, and don't break it when you're screwing it in."

[Rick Parker]

All of which can be done easily if you are unaware of the consequences.

Right Patrick??

[patrickt]

Originally Posted by Rick Parker

All of which can be done easily if you are unaware of the consequences.

Right Patrick??

Yes, that is true.

[Rick Parker]

One more thing, if you do not ha a readily available source for OEM MSD parts, the same pickup is used for mid 70's Fords although the pickup is riveted to a base plate it can easily be removed, wire colorings are the same but the connectors would need to be soldered on from the take out unit. The magnets ARE brittle be careful whether you do the above or use MSD's part. I have both T shirts and felt silly after having worn them

[Murky781]

Ok ... you guys have me scared now! LOL looks like 2 nuts to remove and the whole thing comes out. Already made a drawing of the plug and which side is which for the wires. I just put the dash back in, the steering I'll do tomorrow morning. Another question. I have very carefully taken the rotor out noting the orientation, but I don't see anything that puts it back right, automatically. Last time I changed a rotor it had a key slot on the shaft so you couldn't screw it up. I do notice that I have one blue spring and one natural on the top thingy, blue is to the right if I can read MSD on the rotor, but that's all I see.
Any tricks to installing the mag. pick? looks like mine has some glue between it and the edge of the distributer. haven't removed it until i get the new one so I can match exactly. I'll try Pep Boys in the a.m. Thanks, Murray