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1986 GL no spark from coil to disty


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25 replies to this topic

#1 MadMatt

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Posted 04 August 2011 - 07:35 PM

Got a 1986 GL (EA81) that the engine turns over, but I get no spark. I have checked all the wiring & fuses, replaced the coil & distributor, and patched around the fuel control module (it collapsed 2 months earlier). I also replaced the wire, but still no spark from the coil to the distributor. Everything else works!

#2 GeneralDisorder

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Posted 04 August 2011 - 10:44 PM

You should have +12v to the positive side of the coil with the ignition on. If you don't find out why.

Coil primary winding resistance should be approx. 1 Ohm.

Coil secondary winding resistance should be approx. 10k to 15k Ohms.

It either winding is out of spec - replace the coil.

When you crank the engine you should get a 12v pulse from the negative side of the coil. Use a test light.

If you don't get a pulse and the coil is good and properly powered then the distributor has an issue - bad module or wireing.

GD

#3 MadMatt

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Posted 08 August 2011 - 10:00 AM

Thanks for the response....the coil checks out (primary- 1.6 ohm, secondary- 9,750 ohm) the distributor checks out....I'm starting to think it's a problem with one of the four wires attached to the coil. Let me verify, two black wires on the positive post (the 'hot' wire & the one that goes to the distributor) two yellow on the negative post (one that goes to the dist., & tach wire)...Question: could it be a break somewhere in that yellow 'tach' wire? I know that it can't be on the route to the black box, because the box is giving me the correct problem code (7-3). What equipment is on the rest of that wire? Also- is there an Ignition Control Module on this model year?

#4 GeneralDisorder

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Posted 08 August 2011 - 10:15 AM

For sure you have 12v to the coil +?

How does the distributor check out? Did you get a pulse from the negative side of the coil while cranking?

There is no module. And the tach wire doesn't matter for spark.

GD

#5 MadMatt

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Posted 09 August 2011 - 11:41 AM

Thanks again for the information....Yes, I get 12 volts on my meter from the positive side of the coil. At this time, the only verification that the new distributor works, is that I see it rotate when I crank the car over. There is no pulse coming from the negative side.....Another Question- would the 'air gap' in the distributor be too wide? I just assumed it would be set right at the refurbishing factory.

#6 GeneralDisorder

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Posted 09 August 2011 - 12:24 PM

No pulse from the coil negative when cranking means the distributor module is bad. Air gap, etc would be set at the factory.

GD

#7 MadMatt

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Posted 10 August 2011 - 11:01 AM

Ok, got an update to your question about 12 volts going to the positive post of the coil. I have been using an old analog meter up to this point, but yesterday a friend of mine brought over his new digital meter. AHA! Positive post reading is 11.4, negative post is 0.26 (and no pulse). The yellow 'tach' wire reading is 8.7. There is no reading when measuring from post to post....What would be causing the draw-down of 11.4 and the 8.7 wiring?

#8 GeneralDisorder

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Posted 10 August 2011 - 11:27 AM

Ok - couple things:

1. You need to use a test light to check for the pulse at the negative side of the coil. Digital meters don't respond fast enough and the analog needle might not either. You should see the light flash when you use a test light from battery ground to the negative side of the coil.

2. 11.4 is normal for a 12v battery when the ignition is on and some accesories are drawing power. It should be sufficient.

3. You say the negative post is 0.26v and you say the yellow tach wire is 8.7v..... that doesn't make any sense because they should be connected to each other. The yellow lead from the distributor and the tach wire from the cabin should be attached to the negative post. The black w/white stripe wire from the cabin and the distributor should be attached to the positive.

GD

#9 Cougar

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Posted 10 August 2011 - 10:15 PM

Since you say the minus side of the coil is only .26 volts it means the coil windings are either open or the minus side is being grounded somehow. If the coil gets hot when the ignition is turned on for a bit then there is a ground problem. GDs advice about the tach wire is correct. It sounds like the wiring to the minus side of the coil is not correct.

#10 MadMatt

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Posted 11 August 2011 - 10:46 AM

Thanks to all the info, I think I know what the problem is. At the top of the year, the new fuel pump quit working. I traced it to a nondiscript light blue module bolted to the firewall, underneath the dash. I find out that it's called the 'fuel control module'. I shove a paperclip between the black & blue wires in the connector, and the fuel pump started clicking again. Unfortunately, when I opened the module, the p.c. board fell apart like it was made of dust. So I forgot about it (the car was working). It is obviously affecting the ignition system....Question: Does anybody have a diagram so I could solder up a clone?

#11 MadMatt

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Posted 29 October 2011 - 01:48 PM

Well, it's not the fuel control module. Still not getting a tach pulse, so I don't know what it is.

#12 Cougar

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Posted 29 October 2011 - 05:22 PM

You said there was very little voltage on the minus side of the coil. Remove any wires tieing to that side of the coil and then check the voltage on the minus side of the coil with the ignition switch ON. You should see close to 12 volts there. If you do see that then one of the wires that ties to that point is going to ground somehow.

I assume you are aware that the fuel pump won't run unless the ignition is working.

#13 mm88swrt

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Posted 12 November 2012 - 09:48 PM

Would the same diagnostics pertain to an 87 gl-10 (ea82) ? I'm having the same issues.

#14 Cougar

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Posted 13 November 2012 - 08:28 AM

Yes, the ignition system is basically the same.

#15 mm88swrt

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Posted 14 November 2012 - 06:11 PM

So on my end of the story I've got a new coil, new to me ditsy out of a running car, 12v on both sides of the coil. Slight pulse on - side of coil. It's faint on my test light. Is it possible the ecu got fried? The wires on my old coil were backwards.

Edited by mm88swrt, 14 November 2012 - 06:22 PM.


#16 mm88swrt

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Posted 15 November 2012 - 03:25 PM

Also have no codes from the ecu. Read memory I get no led at all

#17 Cougar

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Posted 15 November 2012 - 06:10 PM

You might have a bad ignitor module.

#18 mm88swrt

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Posted 15 November 2012 - 07:17 PM

Where would this be located? And is there a way to test it?

#19 Cougar

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Posted 16 November 2012 - 11:04 AM

I think the ignitor module is mounted on the shaft of the disty or close to it. It isn't real easy to test it. From what you describe about the trouble it sounds like it is bad.

#20 mm88swrt

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Posted 16 November 2012 - 11:15 AM

Could it perhaps be the little round guy on my strut tower, right below the ignition coil? Runs online off the black wire that goes to the ditsy I think. Not 100% sure of the wire color but it is off one of them for sure. Just so I'm sure we are on the same page mine is an 87 gl10 with the "seeing eye" ditsy

#21 Gloyale

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Posted 16 November 2012 - 11:26 AM

Would the same diagnostics pertain to an 87 gl-10 (ea82) ? I'm having the same issues.


No.

This thread was about a carbed disty.

You have Fuel injection, which uses the Optical Pickup type disty.

Have you checked that the rotor screw is still in place?

#22 Gloyale

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Posted 16 November 2012 - 11:28 AM

So on my end of the story I've got a new coil, new to me ditsy out of a running car, 12v on both sides of the coil. Slight pulse on - side of coil. It's faint on my test light. Is it possible the ecu got fried? The wires on my old coil were backwards.


If your new disty is from any other year besides 87, you will need to swap the position of the Green and the White wires in the disty connector.

87 only, the signal and reference wires are reversed at the ECU......but it's easier to swap the disty to match the ECU, rather than repin the ECU connector.

#23 mm88swrt

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Posted 16 November 2012 - 01:18 PM

If your new disty is from any other year besides 87, you will need to swap the position of the Green and the White wires in the disty connector.

87 only, the signal and reference wires are reversed at the ECU......but it's easier to swap the disty to match the ECU, rather than repin the ECU connector.


Could this switch be done by simply swapping the ditsy plugs? The one i got was off an 88 I believe, had the square 4 pin on the ditsy. My car has the round 4 pin, so I simply swapped the ditsy harness. I will look closer at them to double check the wires match up the same. Is the difference the actual wiring coming off the crank angle sensor itself? Correct me if I'm wrong, you are saying I can take the green and white wire from the ditsy and swap/splice so it has the green hooked up to the white and vice versa?

#24 mm88swrt

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Posted 18 November 2012 - 03:01 AM

Correction, do not have a pulse from the ditsy on - side of the coil.

#25 Cougar

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Posted 18 November 2012 - 11:52 AM

Correction, do not have a pulse from the ditsy on - side of the coil.


I assume that you have voltage on the minus side of the coil while the ignition is on. Make sure fuse 5 is ok and has power to it. Then check for power to the disty leads.




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