I went to check why I am getting no spark to my car last night. Come to find out upon start up the coil is giving no power to the dizzy. I should be getting something from the coil on startup right?

 

Yes. If you pull the coil wire it should be sparking 4 times per engine revolution. Nice hot, blue spark.

Could be a bad coil but it could just as easily be a bad module, pickup, etc. inside the distributor that is causing it not to fire. It can also be a bad tachometer since the pickup for the tach is on the same (-) side of the coil that the module switches on and off.

First things first, make sure you're even getting 12V+ to the coil while cranking. Then diagnose from there. To check the coil I just keep a known-good junkyard unit on hand for easy back-to-back plug-n-play testing.

FYI- the plug on your coil that has wires from the vehicle's wiring harness (not the other coil plug that goes to the distributor) is what supplies both power (big pink wire) and the signal back to your stock tach (smaller white wire).

 

Sorry to hijack, but...

Damon,
Can you expand on the bad tach causing a no-spark condition? I've been battling a problem with my 92RS for several weeks now. I just can't get the thing to spark AT ALL. Nothing. Actually, I got it start about a week ago, but it wouldn't stay running. I assumed this because the timing was off, but when I went to time it it wouldn't start again.
Anyway, I've checked, replaced, and rechecked absolutely every part of the ignition system with no luck. Your suggestion of a faulty tach makes me wonder if I need to be focusing my attention elsewhere.
Thanks!
Dave

 

The tach reads the on-off switching of the ground (negative) side of the coil that the module has control over. The positive side of the coil is always powered any time the ignition is on. The negagive side of the coil is run by the module which alternately provides a ground (charging coil) or breaks the ground connection (firing/discharging the coil).

The tach is only supposed to monitor the - side of the coil. However, if the wiring or the internals of the tach short out in a certain way they can become an alternate ground path, always charging the coil but never allowing it to fire. You get no spark.

Temporarily removing the tach signal wire from the coil connector is a quick way to take the tach out of the loop and see if you suddenly have spark again. Don't clip the wire- just run a short jumper between the coil connector and the coil, but only hook up the big Pink wire- leave the little white wire unconnected. Make sure you know which pole of the distributor that big Pink wire goes to before putting a jumper in it's place- hook it up wrong and you can blow out the module and other stuff.

Diagnose, don't just assume this is the problem. A bad tach causing a no-spark condition is fairly rare, but it can happen. Simply not getting a full 12V to the coil's + terminal (in both the RUN and START key positions) is a much more common problem, as are bad electronics inside the distributor.

 

Thanks Damon, very helpful. I converted this car to TPI a few years ago and the donor car was running an aftermarket tach... there just happens to be a connector I installed to reconnect it to the stock gauges in my car (guy just clipped the white wire about 6" from the coil). So that will come in handy.
I do have 12v+ to the coil with ignition on and cranking, and literally every part of my ignition system is new and checked out good.
The car died on me suddenly too, so something shorting out somewhere kind of makes sense.

Dave

 

im having a VERY similar problem, was the problem ever sloved?

 

anyone?

 

Mine's still down. Can't figure it out.

Dave