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Old 07-04-2020, 04:51 PM   #1
Jmoney01
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Ignition module issue

My girl has been sleeping peacefully in the garage for a few years. Finally got around to messing with her. Now that she's running again, I'm stumped. It is burning up ignition modules almost daily. I have 12 volts to the hei only when key is on. What would cause these to pop? Maybe the truck doesn't like being out in the sun? Any ideas?
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Old 07-04-2020, 05:10 PM   #2
Sheepdip
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Re: Ignition module issue

It's possible your coil is bad. It heats up and shorts out making you think it's the module. Have you tried putting one of the burnt modules back in to see if it fires up? Once the coil cools down it works again for a little while and while you are putting a new module in it's cooling down only to fire up making you think you solved the issue.
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Old 07-04-2020, 05:32 PM   #3
Jmoney01
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Re: Ignition module issue

I've let it sit for a few days between it running and then won't fire. Should be plenty of time to cool off, right?
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Old 07-04-2020, 05:40 PM   #4
toolboxchev
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Re: Ignition module issue

Check the wiring coming out of the HEI, The wires from the module circuit are know to get pinched by tuning on the manifold.

Also use a DVOM to get the actual voltage at the battery, both running and not.

HEI's modules do not like over voltage issues at all. The came out in congunction with the internally regulated alternator.

Here are the finer facts about the HEI and how to diagnose issues:http://www.crankshaftcoalition.com/w...EI_distributor
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Old 07-04-2020, 06:03 PM   #5
Steeveedee
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Re: Ignition module issue

Are you certain that you have the internal ground strap installed? The one that goes under the coil. If left out, you will get this symptom.
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Old 07-04-2020, 06:55 PM   #6
BROWN 70
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Re: Ignition module issue

hi guys, are you putting heat sink compound under the module? when i bought my hei from summit, there was not any under the module. put some on and havent had a problem so far. 3-4 years. also check the ground as stated above, good luck. BROWN 70
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Old 07-04-2020, 08:12 PM   #7
Sheepdip
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Re: Ignition module issue

Quote:
Originally Posted by Jmoney01 View Post
I've let it sit for a few days between it running and then won't fire. Should be plenty of time to cool off, right?
Yep that's plenty! So it's probably not the coil itself.
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Old 07-04-2020, 08:36 PM   #8
HO455
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Re: Ignition module issue

Lots of information in this recent thread that may help you.

https://67-72chevytrucks.com/vboard/...d.php?t=806473
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The WMB repair thread http://67-72chevytrucks.com/vboard/s...d.php?t=698377
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Old 07-04-2020, 08:35 PM   #9
'68OrangeSunshine
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Re: Ignition module issue

You can pull your Module and get it tested at any FLAPS. I carry a spare, known-good Module in the glove box of both trucks w/HEI. A new one averages about $15. Easy swap in the field as a troubleshooting step.
Fresh Module, still no-start?
OK, Coil?
Fuel Pump?
Etc.
Unlike points, you won't have to reset timing.
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