How to tell if a Pertronix Electronic Ignition has gone bad

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cvan1971man

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Arlington, TX
My son came home from college. The 78 '40 was driving fine. One day it just started acting up - stuttering, missing, sporadic backfiring, running bad until you get it up to 40 or 50MPH. even at higher speeds, it isn't running 100%. At low speed it is very sluggish.

I checked the timing, it is correct. I bought new plugs and wires and it didnt make a difference.

It has a Pertonix Electronic Ignition in it and I was wondering how to tell if that has gone bad.
 
cvan1971man said:
My son came home from college. The 78 '40 was driving fine. One day it just started acting up - stuttering, missing, sporadic backfiring, running bad until you get it up to 40 or 50MPH. even at higher speeds, it isn't running 100%. At low speed it is very sluggish.

I checked the timing, it is correct. I bought new plugs and wires and it didnt make a difference.

It has a Pertonix Electronic Ignition in it and I was wondering how to tell if that has gone bad.
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Pretty sure they electrically 1 or 0.
Did you look at the cap and rotor?
 
brian said:
Pretty sure they electrically 1 or 0.
Did you look at the cap and rotor?
Click to expand...
I went out and looked at the cap, it had a bit of oxidation in it towards the top. I scraped that off. The Rotor looked fine. No issues. No cracks in the cap.

It is just odd that it went from running great to - running rough.

I even checked to see if anyone was trying to mess with the vehicle and change the spark plug wire configuration - everything was fine.
 
Given the above scenario. Is there anything else that you would check?

Spark plugs - good
Wires - Good
Coil is kicking out 13.5+ Volts

I did a search for Pertronix issues and ran across this. None of these appear to be what I am experiencing. I'll check "STICKER ON MODULE DAMAGE". That could be the only one that I see. Each of the scenarios below talk about higher RPM issues. All of the main issues that we are experiencing are at lower RPM's.
SymptomDescriptionLikelihood It's the Module
No Spark at AllEngine cranks but won't start; no spark from coil wire to ground.Very high (classic total failure).
Intermittent Misfire/Engine Dies When HotRuns fine cold, then misfires, backfires, or stalls after 20-30 minutes (heat soak).High (overheating damage).
Engine Cuts Out RandomlySudden loss of power while driving, tach drops to zero.High (if restarts cold).
Coil Gets Excessively HotCoil too hot to touch after short run (even with correct coil).Medium-high (module shorting).
Weak or No Spark Under LoadMisfires at higher RPM/throttle.Medium (partial failure).
Sticker on Module DamagedBackside sticker wrinkled, burned, cracked (visible sign of overheating).Definitive (PerTronix official diagnostic).
 
They either work or they don’t if it is acting up the igniter should be fine. Also for the burned sticker sometimes they can looked burned and you can see a black spot burned through the face by the magnetic pickup and it is still fine that Sticker burn thing isn’t always correct either. They can still get warm and wrinkle. Did you pull the igniter plate and pickup out and clean underneath ? For fun ground the distributor body and see what happens they are finicky on bad grounding also. Also what is the voltage at the igniter itself they like 12-14 volts to be happy.
 
Sounds like the pickup module may have come loose
 
Take the carb apart and clean, check the bowl, flush fuel pump, filter, lines. Also, When these random things pop up I like to check voltage, many times a simple corrosion on a fuse block terminal lowers supply voltage causing many random symptoms sending people on long, mysterious searches, worth a check.
 
peesalot said:
Take the carb apart and clean, check the bowl, flush fuel pump, filter, lines. Also, When these random things pop up I like to check voltage, many times a simple corrosion on a fuse block terminal lowers supply voltage causing many random symptoms sending people on long, mysterious searches, worth a check.
Click to expand...
Good call on the carb ,, his post had me thinking just about the pertronix. Haha.
 
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