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1987 305 suddenly stopped running - no spark

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Old Nov 22, 2010 | 03:10 PM
  #1  
Chris51's Avatar
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1987 305 suddenly stopped running - no spark

My Z28 suddenly stopped running last year and I am finally trying to get it going again.

I determined that it wasn't getting spark, even though I have power at the coil. Looks like the ECM is not pulsing the coil. Fuel pump, etc seems fine.

I changed the coil, cap, rotor and ignition control module. Insides of the distributor were really nasty, so I bought another just in case.

Only thing that looks suspicious at this time is that I have 12v on one side of the ECM fuse in 'run' position and about 4v on the other side with the fuse removed. This doesn't seem normal to me. Is it?

Otherwise, I am thinking that I have a short somewhere, but really don't know where to look.

Thanks.
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Old Nov 22, 2010 | 05:02 PM
  #2  
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From: Mid Mo.
Car: 1989 GTA - Gunmetal grey
Engine: 5.7 ltr.
Transmission: 700R4
Axle/Gears: 3:27 9 Bolt Borg Warner
Re: 1987 305 suddenly stopped running - no spark

How about checking your electronic ignition module under your distrubitor cap ?
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Old Nov 22, 2010 | 05:31 PM
  #3  
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Re: 1987 305 suddenly stopped running - no spark

I replaced the ignition control module but not the distributor pickup coil. For this purpose, I bought a complete distributor, as others have told me that the control module and pckup coil should be replaced in pairs, and to get to the coil you need to remove the distributor.

Next on my list of things to do, but I wish there was I way I could test it first.

Thanks for the input.
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Old Nov 22, 2010 | 06:24 PM
  #4  
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From: Dardanelle, AR
Car: 1985 El Camino SS, 2004 Trailblazer
Engine: Hybrid 305, 91 SD TPI, lots of mods
Transmission: 200-4R
Axle/Gears: 3.42
Re: 1987 305 suddenly stopped running - no spark

The ECM does not control the spark, just the timing advance. You should have a spark even with the ECM disconnected. The ICM makes the coil spark and the ECM controls the timing EXCEPT on 85 and 86 models with an external ESC Module. Is the distributor shaft turning when you crank the engine?
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Old Nov 23, 2010 | 03:04 PM
  #5  
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Re: 1987 305 suddenly stopped running - no spark

Distributor turns.

When the car quit, it was just idling in the driveway. Started up fine prior to that, and had run relatively well, considering that for 2 years prior to the previous 2 months it just sat.

Only thing that I can think of at this moment is the distributor coil pickup. The pickup and the ICM were pretty nasty - covered in a brown goo. The plug from the pickup to the ICM had disintigrated, and the connections were green with corrosion.

Next on my list is to replace the distributor. Now, if I could only find my timing light.

My other note about 4v on the ECM side of the fuse with the fuse out is apparently normal, as this is just the computer backfeeding as it drains off energy.

Thanks for the reply.
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Old Nov 23, 2010 | 03:14 PM
  #6  
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From: San Antonio, TX
Car: 1989 Trans am
Re: 1987 305 suddenly stopped running - no spark

check my no spark thread out, hopefully that will help https://www.thirdgen.org/forums/tech...989-trans.html
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Old Nov 24, 2010 | 05:06 PM
  #7  
Chris51's Avatar
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Re: 1987 305 suddenly stopped running - no spark

Looks like someone added an aftermarket coil in this instance, which explains their problem.

My car is totally stock and has the correct connection at the coil. I have power to the coil/ICM, but the coil isn't getting pulsed, so no spark. I will replace the distributor in the next day or so, and hopefully the new distributor coil pickup will cure the problem.

Thanks for the feedback.
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