Diagnosing Distributor - No Spark Chase

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Below, distributor "one wire" test. I have removed the other distributor wire for simplicity. Take the bare connector end or this clip lead (the yellow) and with everything hooked up, ground it repeatedly. Each grounding should result in a spark (In this photo you need to hook up the ECU ground wire, I left it off for the photo)


So I finally got around to trying this out. I don't get any spark, but I do get an electrical buzzing of sorts that sounds like its coming from the coil every time I ground it out. It is more of a constant buzzing if i leave it grounded. What is this telling me? Its car week out here in montery and everyone else is driving their cool cars around town I feel left out.
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Ok did this system EVER work? If so, we can assume it's wired correctly. If it did not, I would recheck the wiring carefully. Make certain that when you are grounding the trigger wire, that the coil + continues to remain at at least 8V or so. You might ALSO try jumpering the coil+ directly to battery just to be sure

Otherwise I'd try whatever you can get easily / cheap, coil or ECU and replace one or t' other. Coils for testing do not need to be exact, or grounded. If you can drum up another coil "of of something" I'd try that first.
 
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67Dart273 said:
Make sure you have power to coil + WHEN CRANKING

Measure power to coil + both with key in "run" and in "crank"

With power in "run" disconnect distributor connector. Take the engine harness end of the connector, and tap the exposed terminal onto ground. Each time should produce a "snap!" spark at the coil

Remove/ and work all connectors in/ out several times to scrub the terminals and "feel" for tightness, ESPECIALLY the distributor. Examine them with a flashlight for corrosion

Remove cap, inspect for dirt/ water in cap, rotor "punch through." Inspect the reluctor/ pickup for damage, rust, debri, and shaft wiggle. Set the gap I've forgotten, .008" I think. INCHES, not mm. Make certain the reluctor and pickup don't touch. TB above already posted checking for AC voltage

MAKE ABSOTLUTELY CERTAIN that the ECU is grounded!!!

Measure coil + voltage with key in run........should be no less than say, 6V and no more than, say, 10V. Measure coil NEG it should be quite low, say, 1-3V or so. If you have a tach DISCONNECT THE tach wire for testing. The tach may be shorted
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Do not hold that connector on ground; this must be a tap.
And it is a one-tap/one-spark deal.
and the coil wire must be removed from the cap,and near-grounded for you to witness the ONE spark.
 
sorry to revive a dead thread. Life has been crazy. I got a new chepo ignition module and still nothing.

I've noticed that I get 12 volts at both the positive and negative terminals of the coil when the ignition is in run. when it is in crank the light is a little duller but appears to be the same at both terminals. Is this normal? Also, there is no spark coming from the coil which bench tested ok.

Thanks for helping! I'm still trying to get a good grasp on the electrical side of things.
 
you can't bench-test a coil in the usual way.
You have to make and break the negative side very rapidly. What I do is use a long coarse file like a set of points. Just strip off a half inch of insulation off a wire and jumper the other end to the coil (-), and ground the file back to the power source. Then lightly caress the file with the bare wire. As the wire bounces from high point to high point, a good coil will issue a stream of sparks from the center tower, to the ground return, when near-grounded.
 
perko said:
I've noticed that I get 12 volts at both the positive and negative terminals of the coil when the ignition is in run. when it is in crank the light is a little duller but appears to be the same at both terminals. Is this normal? Also, there is no spark coming from the coil which bench tested ok.
Click to expand...
Yes and no.
With the coil not grounded on the (-) side; The test light should be brighter on crank than on run, and the crank voltage to the coil should be near battery voltage, while in run it should be down at about 60% of battery voltage...... but you will have to wait for the ballast to get hot to measure the final voltage. Recall that this is with the coil (-) disconnected, and open circuit, so the ballast will not get got. You will have to pull some amps thru it to warm it up.
With the coil (-) open circuit, both sides of the coil will read similarly but not the same, because the MOPAR coil primary side is just a really long thin wire spooled up inside the canister. This is not true with an old GM coil, which looks the same but may have the ballast internal. These coils are usually stenciled with I forget the wording, maybe " not for use with external resistor", or something that means the same. If you have a Mopar, you gotta use a Mopar-specific coil.
 
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update:
Well, I re-did the ignition system bench test. I must have done something incorrectly last time, but this time I was able to determine that there was something wrong with the distributor. I put a new one in and now I have spark! Thanks 67Dart273 that was really helpful!

Unfortunately its still not starting and it seems to have developed a new problem. when the engine is turning over it periodically makes a scary grinding sound and stops turning over. But when i try again it will turn over like normal? Weird? just one thing after another.
 
final update:
project was on hold for a long time due to weather and life. Turns out it WAS the distributor I just screwed something up with the test. Also, right after i installed the new distributor It ran for like ten seconds and then the coil went out so i thought i'd screwed something else up.

Anyway, thanks for the advice everyone, especially Dart273. The photos of the testing with jumper leads really helped and when I did it right it totally worked. Anyway, hope this thread helps someone else. Made my life a lot easier. Thanks!
 
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