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kalamykid, Shop Owner/ Tech
Category: Chevy
Satisfied Customers: 4182
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1993 chevy: distributor/module, cap, rotor, plug wires and plugs

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1993 chevy s-10 pickup

Died instantly driving down the road at 55 mph. Towed home and found it had no spark. I replaced the distributor/module, cap, rotor, plug wires and plugs.

I now have spark coming from the coil (hooked a spark plug coming straight from the coil to the block) but I have no spark from the distributor cap to the spark plugs. I am stumped!


this could be a weak coil,,these will do this sometimes..also,the rotor is the only thing between the coil and the wires,,these rotors will sometimes burn a pin hole in the bottom of them..causing them to ground out...may be a weak sure to remove the distributer cap and make sure the rotor is turning,i have seen the gear strip off of the distributer


please ACCEPT my answer so I can get credit for my work.i don't receive commission unless you do ..I'm not always going to be giving you good news,so please don't let this stand in the way of you accepting my does not cost you more money.we will still be able to communicate.. Bonuses and positive feedback are appreciated!if you are not satisfied with my answer,please do not leave bad feed back,i will gladly opt out and let another expert handle the question.PLEASE ASK IF YOU NEED MORE HELP

Customer: replied 7 years ago.

I just installed a brand new coil ....since your advice.


It sparks fast and blue from the coil to a spark plug grounded to the block.


STILL no spark to the plug from the distributor cap! (I have tried 2 different cap and rotors from 2 different companies.)

Rotor is turning


this makes no sense to me if it isn't the rotor..i will opt out..maybe one of the other guys has an idea


Customer: replied 7 years ago.
Ok. Thanks for your honesty. I am rarely stumped....this one has me scratching my head. I have asked alot of mechanics, no one seems to have an answer.
Customer: replied 7 years ago.
Relist: Didn't have the answer I needed. Very professional, honest and straight forward. Seemed knowledgable..
Didn't have the answer I needed. Very professional, honest and straight forward. Seemed knowledgable.
Do you have a vortec engine or a tbi engine?
Customer: replied 7 years ago.
4.3 TBI? what's the difference?
The two engines use two totally different distributors and ignition systems. If you can tell me the 8th vin digit I can tell you which one you have. It will be a w or a z. W is a vortec and the z engine is a tbi.
Customer: replied 7 years ago.

I am almost positive it is "Z"


I m not home to check now.


There is nothing special inside cap/rotor can I have good spark from the coil to the distributor cap and nothing to the plug wire and plug?

Before I can answer that I need to know what distributor you have.Is there any one at home that can check the vin for you?
Customer: replied 7 years ago.
I have seen the rotor button not be put on correctly or not all the way down and when you put the cap back on the rotor button will catch the bottom side of the cap and not let it spin. There is a notch on the shaft for the rotor button to go down over. There is a bump inside the hole in the rotor button that must match up with the notch and the rotor button bushed all the way down. Most often the rotor button is not pushed all the way down when I have seen this problem in my shop.
Customer: replied 7 years ago.

I will check it. The rotor can only go on one way as there is a groove in the underside of the rotor that fits the slot in the distributor shaft. I would think it would strip or snap if caught on the cap as the engine turns over fine.


It HAS to be a cap/rotor issue doesn't it? Nothing else in there....



If you are getting good spark out of the coil then yes it has to be a cap or rotor button problem. When you take the cap back of before you do anything to the rotor try to turn the rotor button, if it turns look to see where it is turning "the rotor not the shaft or the shaft is turning with the rotor".
Customer: replied 7 years ago.
Thank you. It seems embarrasingly simple but I will check it and close this out in the morning.
Just let me know if you do not find anything and I will do my best to help you solve this problem.
Customer: replied 7 years ago.
Didn't work. The rotor is firmly seated in the only position it can be placed in. The rotor and shaft do not turn by hand but the rotor turns normally when the engine cranks. Still no spark from the distributor wire to the plug. Plenty of fast blue spark from the coil wire.

Where does the coil wire go on your cap?

Here is a diagram of what wire goes where.graphic
If you put the coil wire on a post for one of the plug wires by mistake you will not get a spark to the other plug wires accept for one, and that would be the spark plug wire that is connected to the coil post and will only fire once per revolution of the rotor button.
Customer: replied 7 years ago.

Definitely not. Coil wire is in the top center of the cap.


I don't understand why if I'm getting spark to the top of the cap, why it is not being distributed to the plugs.


1) Does the top carbon pin located on the underside of the cap (from coil) have to make contact with the rotor? There is no way to know if it is...and the cap and rotor seats firmly and evenly.

Yes the carbon pin must contact the rotor button. Did you pull the cap off and see if you could see spark inside the cap? " you will need to leave it upside down to be able to see inside the cap to see the spark?
Have you replaced the coil? If the coil has a crack in the tower the spark can leak out to the body of the coil. Spark will always take the path of least resistance.
Customer: replied 7 years ago.
Replace the coil. No change.
When you checked for spark out of the coil did you leave the coil wire in the coil and put a spark tester into the other end of the coil wire?
Customer: replied 7 years ago.
I put a plug in the coil wire and grounded to the block while turning the engine over.
Are you near the truck now?
Customer: replied 7 years ago.
no, I'm "working"
When you get home take the cap off and turn it upside down and see if you see sparks jumping with some one trying to start the engine. Also spry some water form a squirt bottle on the coil wire to see if the spark is jumping out and not making it into the cap.
Customer: replied 7 years ago.
If I take the cap off, there won't be an electrode close to the center carbon tab on the inside of the cap....I don't think it will spark with the gap so wide.
If the coil and coil wire are good it should jump the distance.
The spark from the coil should be able to jump a distance of at least 3 inches to a ground.
Customer: replied 7 years ago.

I'll try it......


This is a tough one......

Yes this one is one for the books. But we will find the problem. Do you have a multi meter? Can you check to see what the voltage is at the coil?
Customer: replied 7 years ago.

I have a multimeter.....


voltage could be 5000-40000 depending on the coil.


I can tell you the spark was fast and blue white which has always been my standard for a strong spark.


I have been working on this for 4 days now and have asked tons of people...No luck yet.


1) If there is spark going into the cap, it HAS to be going somewhere or stopped by something.

Not the output of the coil but the voltage going into the coil from the ignition switch.
Customer: replied 7 years ago.

I tested it a few days ago...12+ volts

continuity read within book parameters on all leads.

That is what it should be. Check the spark again in the morning when you get off of work. This time when you check for spark use a screw driver in the cap end of the coil wire and see how far the spark will jump, then do the cap check as described above.
Customer: replied 7 years ago.

screw driver in the cap end and hold varying distances from the block?


Yes but make sure the screw driver has a good plastic handle so you do not get shocked.
Customer: replied 7 years ago.

I won't be holding it.....I'll check it in the morning.



You must have a younger brother.
Customer: replied 7 years ago.


Poor fella.
Customer: replied 7 years ago.
I'll check it and get back with you tomorrow.


Customer: replied 7 years ago.

1) Turned the cap over and tried starting it. No visible spark.


2) Put screwdriver into wire coming from coil and attempted to have spark fump to ground. .......Nothing.


3) Rechecked voltage to coil. connector from wiring harness :

Pink and white wire = 0 volts

Pink wire and block (ground) 12.5 volts


4) I continue to have fast, bright blue/white spark from coil wire to plug/block ......No spark from distributor to plug.

You have two plugs that go to the coil, one from the distributor and one from the engine wire harness. Both plugs should have a pink and a white wire. If you unplug both of them do you have 12 volts to the pink wire from the engine wire harness?
Customer: replied 7 years ago.
Yes. when I connect one multimeter lead to pink wire and one to block (ground)= 12.5 volts
With the ignition switch on both coil plugs plugged in do you have 12 volts to the white wire?
Customer: replied 7 years ago.

How would I check if they are plugged in? ....splice a wire?

If you take the test lead it should fit down the side of the wire into the plug itself. If it will not then take a safety pin and poke a small hole into the cover of the wire and then stick your test lead to the safety pin. This will not hurt the wire.

Do you have a test light? If not can you barrow one? If you can not then you will need to make one or go get one to do the next test.

Edited by kalamykid on 3/20/2010 at 2:41 AM EST
Customer: replied 7 years ago.

Ok. I will test tommorrow. I am working now.


I am assuming that the white wire must be a control from the computer?

I do believe I know what is wrong with your truck. The pick up coil is bad in the bottom of the distributor. If you take the cap back off unplug the pick up coil from the back of the ignition module and check the resistance of the two leads. Then check the resistance of each wire to a good ground. With you multi meter set to ohms, when you test the two wires for continuity the meter should read 0.000. then check against a ground, it should read 0.L. If you get a reading of 0.L across the two leads replace the pick up coil. If one or both wires show 0.000 then replace the pick up coil.
Customer: replied 7 years ago.
I will go out and check it now. It would be odd..the distributor is new, I already replaced it.
I have seen them bad before on a rebuilt distributor. Any time you are dealing with electronics there is a 60-40 chance that it will actually be good.
Customer: replied 7 years ago.

I checked the pickup coil per the haynes manual:


I connected the multimeter (ohms) to the two connectors from the pickup coil plug and got "805" The book says I should have a steady value between 500 and 1500 ohms.


I connected one end of the multimeter to one of the pickup coil plug contact and the other end to a ground and got "1" which I believe to be infinity (normal)


When I connect both ends of the ohmmeter to each other It goes from "1" to 0000

which I believe indicates the ohmeter is working correctly.

If you are getting a 1.0 then the wire in the coil is shorted to a ground. What is the reading on your multi meter set to ohms with the to leads not touching anything but air?
Customer: replied 7 years ago.
what are the readings when you touch the two leads of the meter together?
Customer: replied 7 years ago.
And when you tested the wires for the pick up coil to ground did any of them show 0000?
Customer: replied 7 years ago.
No. It remained unchanged at "1"
Now that I have all the data I can tell you there is a problem with the ignition module. All the test point to a bad module.
Customer: replied 7 years ago.
I guess I will replace the distributor again as the module was part of the distributor I replaced. Is there anything that would make the module go bad?
There are so many things that can cause the module to go bad. It could have been dropped during shipping, got to close to a magnet. All I know is the one you have is bad and it was not your truck that caused it.
kalamykid, Shop Owner/ Tech
Category: Chevy
Satisfied Customers: 4182
kalamykid and 4 other Chevy Specialists are ready to help you
Customer: replied 7 years ago.

When the leads of the ohmeter are not connected to anything that reading (in my case"1") would be considered infinity right?


The reason I ask is that if it is the Haynes book tests of the pick up coil that I performed shows "normal"

Yes you are correct. The pick up coil is not the problem. You are not getting a good ground form the module to the coil on the white wire. The ground will be in a pulse not a constant.
Customer: replied 7 years ago.
Thanks. I will replace the distributor again in the morning. I will advise you what happens/close this out. You have been very helpful.
please let me know if this fixes your problem. Thank you
Customer: replied 7 years ago.

You were right on the money!


The Distributor/ignition module that I bought (new) was defective. I replaced it with another new one and it fired right up. The truck runs better than it did before!

I am glad you are happy. Thank you for the GREAT feedback you left for me and the bonus. Is there any thing more I can do to help you with your truck?
Customer: replied 7 years ago.
Nope. Your great. Later.
Thank you for coming to just