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The engine turns over but no spark, no start?

Tiny
SOLO58
  • MEMBER
  • 1975 CHEVROLET CORVETTE
  • 5.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 71,000 MILES
Engine quit while driving. Carb is getting fuel, tried either. Still no spark. Replaced cap, center spring, coil, ignition module. No spark but will turn over. Checked coil with multimeter primary.2 and secondary8.14 coil are good. Checked voltage to distributor and good 11.8.
Checked compression on 2 cylinders on off chance that timing chain jumped. 110 pounds in each cylinder. I don't know where to go next. Ignition switch on column maybe?
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Tuesday, September 3rd, 2024 AT 3:06 PM

5 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
Hi,

It sounds like you have already done a lot. Have you checked the pick-up coil in the distributor? That will prevent spark if it has failed. See pic below.

If you have a spare distributor you could try, that would help eliminate any of the internals.

Let me know. Also, and don't laugh, remove the distributor cap and confirm the rotor is turning when you crank the engine. Also, if there was a timing related issue, you would still have spark. It would just be at the wrong time.

Let me know.

Joe
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Tuesday, September 3rd, 2024 AT 8:12 PM
Tiny
SOLO58
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  • 3 POSTS
Good morning, Joe, thanks for the input. Yes, the distributor is turning. No laughing here. This morning, I tried running a direct line from battery to distributor 12.59 V. Didn't work either. You said something about the pickup coil? I don't want to seem stupid but is that the circular ring of magnets I. The pic. I have an MSD HEI ignition not stock. I will check back on your answer. One other thing. In the past when I turned the key on, the gauges all jumped up indicating the circuit was energized. The tachometer no longer does that.
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Wednesday, September 4th, 2024 AT 8:00 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
Hi,

If the tachometer doesn't move, that is a good indication there is no RPM signal. Yes, you are correct about the pick-up coil. And yes, it can cause a no spark condition. It functions much like a crankshaft position sensor does on a newer vehicle.

If you have a spare distributor, switch them to see if that changes things.

Let me know what you find.

Joe
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Wednesday, September 4th, 2024 AT 8:01 PM
Tiny
SOLO58
  • MEMBER
  • 3 POSTS
Good news, when you mentioned the magnetic pickup, I went to Ohms to check it and found that the power wire in the harness had back out of the retainer clip enough to break contact. I reinserted the wire and she started right up. Problem solved. Should have checked the harness more thoroughly. Thanks for your help!
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Thursday, September 5th, 2024 AT 5:08 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,700 POSTS
Hi,

Thanks for the update. I'm glad you found that. Things like that can drive you crazy. LOL

Regardless, take care of yourself and feel free to come back anytime in the future.

Joe
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Thursday, September 5th, 2024 AT 6:59 PM

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