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No spark? [1985 tpi L98]

8

85Fever

Guest
Greetings,
I have a 1985 corvette that lost its spark. It died over a year ago and I can not figure out why I can not get a spark. I have tested or replacement almost every component of the distributor yet I do not get any spark out of the plugs. I've done almost every check out of the service manual. Any suggestions?

John :W
 

Achilles

Well-known member
Joined
Oct 31, 2004
Messages
447
Location
Back in Sunny California!
Corvette
1982 CE, 03 MY Z06
With the ignition on, do you have power to the "Battery" terminal of the distributor cap?

If so, check the coil.

If the coil checks out ok, could be the ignition module has gone bad inside the distributor.
 
8

85Fever

Guest
thanks

Assuming that everything in the distributor is good, is there anything outside of the distributor that could cause a no spark condition. So far everything in the distributor has been replaced, and I have 12v at the battery terminal of the distributor.
 
8

85Fever

Guest
Just the 2nd post ... to make sure my response wasn't missed... thanks for inquiring... we have no spark to any plug
 
8

85Fever

Guest
response

ignition coil has been replaced
and the module has been replaced
everything as been replaced.

it is so hard to figure out. Everything on that distributor has been replaced. double checked... is there anything else that could cause that?
 

McSnagg

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Joined
Nov 26, 2006
Messages
59
Location
Nebraska
Corvette
1988 Triple Black Convertible Z52 4+3
Is the distributor rotating when the cap is off?
 

Achilles

Well-known member
Joined
Oct 31, 2004
Messages
447
Location
Back in Sunny California!
Corvette
1982 CE, 03 MY Z06
If the "pick up" is bad, you have to remove the dist., drive the pin out to remove the dist. gear and slide out the dist. shaft to replace. Or just replace the whole distributor. It sounds like that is what is causing you the trouble. But I would still check to see that the new parts you have already replaced might be defective. Just because they're new doesn't mean they always work. You can take things to Autozone or Napa to have them checked out.
 
8

85Fever

Guest
response

yes it is definitely spinning also the pickup coil was replaced even though it tested good. Module was replaced but that had tested bad... it failed at advance auto. computer terminal board and leads tested good (4 wire ecm cable passed continuity test). Ground seems to test okay.... thanks

Is the distributor rotating when the cap is off?
 
8

85Fever

Guest
Complete response

I'm writting this for my father. He just wanted ya'll to know that he has been a long time not a mechanic but grew up with cars, so its not a "have no clue about a car question". He's been trying to diagnose it for a year and still hasn't been able to fix it. it's been sitting in the garage for all this time. He's run almost all the tests in the shop manual.

The 1985 service manual page 6D-27 step 5 and 6 seem impossible to do because he gets zero voltage at the tach. Except up on step 3..

what is the coil output terminal? (step #4) ?
 
8

85Fever

Guest
the is the shop tests. What should we run?

corvette.jpg
 
8

85Fever

Guest
tests

I can not see the purpose of #4 because if they are referring to the output terminal of the coil, they must mean the little plate that goes into the center of the distributor button. Which feeds down into the rotor, which feeds into the indiv. spark plug leads. Assuming the wires are good and the rotor is good, and making contact with the center coil button... it serves the same purpose as number one.... comments? plus to get to that... the output terminal if they are referring to to that center button. You have to have the coil out or the cap off to do that test. :confused
 
Joined
Aug 30, 2002
Messages
1,533
Location
Colorado Springs, CO USA
Corvette
84 Z51 auto R.I.P. 89 black roadster SOLD
Don't have time to look through the chart at the moment, but a thought...

The HEI coil has a small tab that sits underneath one of the corners...for the ground connection maybe? Been a while since I've looked at one so I don't really recall. Could that be not making a good electrical connection?

Bill
 

navy2kcoupe

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Joined
Dec 16, 2006
Messages
799
Location
West Central FL and SE Mass.
Corvette
2000 Navy Blue Coupe A4 Z51
The 1985 service manual page 6D-27 step 5 and 6 seem impossible to do because he gets zero voltage at the tach. Except up on step 3..

what is the coil output terminal? (step #4) ?
Are you trying to measure the voltage at the tach itself? If you are, I don't think that's where you should be looking. I think that you should be measuring for voltage at the terminal on/near the distributor that's refered to as "the tach terminal" because that's where you would connect a tach if there was one. Don't know if that's what your problem is or not, just thought I would chime in when it sounded confusing to me. Maybe someone else with more experience on 85's will put in their 2 cents worth.
Andy :w
 

Achilles

Well-known member
Joined
Oct 31, 2004
Messages
447
Location
Back in Sunny California!
Corvette
1982 CE, 03 MY Z06
I can not see the purpose of #4 because if they are referring to the output terminal of the coil, they must mean the little plate that goes into the center of the distributor button. Which feeds down into the rotor, which feeds into the indiv. spark plug leads. Assuming the wires are good and the rotor is good, and making contact with the center coil button... it serves the same purpose as number one.... comments? plus to get to that... the output terminal if they are referring to to that center button. You have to have the coil out or the cap off to do that test. :confused

Sounds like what #4 is refering to is the button under the dist. cap. If so, yes you would have to have the cap off and enough slack in the ingition wire to have it still connected to perform this test while cranking the engine. I personally have never had to do this test before since I've always been able to resolve the issue without this test. But if the coil tests good, I would check what the other poster suggested regarding the ground strap under the coil. Also is the rotor cap making contact with the coil button. I know these may sound very basic, but if you've replaced everything, I have a feeling it is something very simple that is causing the problem. The only other thing I can think to try is a junkyard distributor to see if that makes any difference before spending big $$ on a new one.

BTW, are you getting 12 volts to the dist.
 

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