Spark at coil and distributor but no spark after plugs installed and crank at key

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Duster509

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All my 1972 Duster seems to be having electrical issues. I have done the following:

-New battery
-New heavy cables
-New ignition switch
-New starter
-New starter relay
-New ballast resistor
-New coil
-New Distributor cap
-Pertronix electronic ignition conversion
-New plugs and wires
-Additional grounding cable from cylinder head to master cylinder bolt on firewall

I take a spark plug out and hold it the the engine block while bumping the starter relay and I get spark and the engine cranks beautifully. When I put the spark plug back in the cylinder head and try to start it with the key it cranks as it should for 1-2 seconds then it’s almost as if the motor is bound up or like I have a weak battery then goes back to cranking ok for 1-2 seconds then binds up again. The moment I release the key it shoots smoke out of the carb. I then go pull a plug and try to bump again from the relay but now no spark. I’m at a loss, can anyone point me in the right direction?
 
THIS QUESTION --and I'm not trying to preach, but rather simply make a point.........is exactly why it is important to understand the Mopar electrical system

When you turn the key to "run" and start it by jumpering the starter relay, the key switch is providing power to the ignition system, through the ballast resistor

BUT when you crank the engine by using the key "in start" you change the entire system

First, the key KILLS the "run" voltage (IGN1) to the ballast during "START"

That power is replaced by a SEPARATE contact in the ignition switch, (usually the brown wire) which runs out the bulkhead connector and goes to the coil+ side of the ballast. So the coil is supposed to get power by this wire in start

IF you have something an aftermarket, MSD, etc, ignition, and you have not properly bypassed the ballast, you may not have included the brown/ IGN2/ bypass circuit, and will not get spark at the coil in "start."

If you DO still have the ballast resistor in circuit, it may be that the ignition switch, it's connector, or the bulkhead connector is losing connection.

IF you do not have one, run over to "MyMopar" and download a free service manual, as well as the aftermarket 2 page wiring diagrams, which are not as detailed, but may be sometimes easier to follow
 
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The easy way to set up a pertronix is to pull power off the coil + terminal, leaving the original coil + wire in place, then go and bypass the resistor

If you had breaker points, either connect all wires at the 2 post ballast together or make a little jumper with male 1/4" flag/ spade terminals and plug it in just like the ballast.

If you had electronic, and a 4 wire ballast, look at the wiring. Two of the wires at one end have a short jumper from factory, so that amounts to 1 junction. The other two wires, one goes to the coil, the other goes back to the box. You do not need the "box" wire, so take the two at one end that are jumpered, and jumper them to the coil + wire and off you go
 
I'm guessing he just now installed the Pertronix
 
Duster509 said:
The moment I release the key it shoots smoke out of the carb
Click to expand...
Check and recheck the firing order, and rotation direction.


Some of what you are saying sounds like what 67dart273 said but some sounds like you have the firing order off or the timing is way off

You don't really know if you have no spark when everything is put back in place, you just know it won't start.

So if the firing order was off you could get firing on an open intake maybe and if it was too far advanced or retarded it could pop out the intake too
 
My friend just went through this with his E-body. Check and confirm that every connection is where it is supposed to go. My friends problem was at the bulkhead connection, power into and back to the firewall connector, but wasn't coming out of the connector to the coil.
 
I had a similar issue.

It was an intermintent connection at the firewall bulkhead connections.
Had spark on "start" but when I let off the key to transition back to the "run" position it would not run.
In my situation it was difficult to diagnose and it was happening randomly on a good running car otherwise. Figurrd it out after 7 hours of troubleshooting.
Cleaned the bulkhead (firewall) plugs real good and was back on the road to Virginia for an autox weekend that evening.

Good luck!
 
Dana67Dart said:
Check and recheck the firing order, and rotation direction.


Some of what you are saying sounds like what 67dart273 said but some sounds like you have the firing order off or the timing is way off

You don't really know if you have no spark when everything is put back in place, you just know it won't start.

So if the firing order was off you could get firing on an open intake maybe and if it was too far advanced or retarded it could pop out the intake too
Click to expand...
He may be getting some spark when he releases the key, and the engine is still moving a bit
 
67Dart273 said:
He may be getting some spark when he releases the key, and the engine is still moving a bit
Click to expand...
Agreed, but if it was timed correctly or firing on the right cyl I would not expect fire throught the intake.


As you pointed out it is super simple to check voltages at the ballast resister under start and run conditions.

And to check the firing order and the timing. If the dist was pulled to install the proteomics the dist might be180 out for that matter.

The thing that gets me is, spark and free cranking with a plug out, odd cranking and carb pops with the plug in.
 
Just checked and my firing order is correct. Bypassed the resistor and I’m still experiencing the same issue. Ran through the ignition again and I get spark from coil as well as to the plug when I jump the relay. I had a helper observe the spark plug to engine block while I tried from the key this time and it had spark, which is good news, but the cranking went back to sounding weak and bound up, this time with the plug out. It only does that when I start from the key, when I jump from the relay it cranks as it should.

I will check bulkhead connections tomorrow and maybe that is where the problem is? Anything else I should check?
 
Duster509 said:
Just checked and my firing order is correct. Bypassed the resistor and I’m still experiencing the same issue. Ran through the ignition again and I get spark from coil as well as to the plug when I jump the relay. I had a helper observe the spark plug to engine block while I tried from the key this time and it had spark, which is good news, but the cranking went back to sounding weak and bound up, this time with the plug out. It only does that when I start from the key, when I jump from the relay it cranks as it should.

I will check bulkhead connections tomorrow and maybe that is where the problem is? Anything else I should check?
Click to expand...
Get a multimeter. Connect to the coil + and ground. Since you have the resistor bypassed, turn the key to "run" and you should have very close to "same as battery."

Twist the key to start and read meter while cranking. Once again you should have very close to "same as battery."

Connect meter to battery. Turn key to run. Note reading at battery, then crank and read meter while cranking, and again note meter reading

Unless you have upgraded the wiring, ALL these girls have some wiring voltage drop. If the readings between battery and coil are more than 1/2V apart you need to dig in.

Post results here.
 
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Have you verified the engine is in time? Found TDC with a piston stop?
 
Duster509 said:
It only does that when I start from the key, when I jump from the relay it cranks as it should
Click to expand...
When cranking from the relay is the key in the run position?

Was it in the run position the last time when it sounded like the other times from the key?


How do you know that the distributer is timed propperly?
 
Duster509 said:
Just checked and my firing order is correct. Bypassed the resistor and I’m still experiencing the same issue. Ran through the ignition again and I get spark from coil as well as to the plug when I jump the relay. I had a helper observe the spark plug to engine block while I tried from the key this time and it had spark, which is good news, but the cranking went back to sounding weak and bound up, this time with the plug out. It only does that when I start from the key, when I jump from the relay it cranks as it should.

I will check bulkhead connections tomorrow and maybe that is where the problem is? Anything else I should check?
Click to expand...
Oh so it actually RUNS? Is that correct? Sorry if I missed that buried in all this "other" mess.
 
Are you sure there is NOT some foreign liquid inside the cylinders ?
I would take out all the plugs and crank it.
If that works, and nothing comes out, then I would suspect the starter ground , or the starter itself.
To test the ground I use a booster cable from battery neg to the starter case. Normally the starter grounds to the bellhouse then block, then to the cable at the driver's side front, then the battery. Corrosion or paint, at any junction can prevent good contact.
To test the starter, I remove it and clamp it solid in the bench-vise. Then connect a battery to the appropriate terminals. I use a remote starter to energize the solenoid, but in a pinch you can use a screwdriver. If it spins that's a good sign, but you still gotta load test it.
To load test the starter, I use a wooden stick rubbing hard on the starter drive. If I can't stall it, then it goes back on. If I can stall it, I take it apart and figure out why, or I replace it. If I obtain a replacement starter, I test it just the same.
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The basic Mopar ignition test is the one-spark test.
In a factory stock Mopar System, every time you cycle the key from run to off,
the coil should send one spark to near-ground. If it does, them the entire ignition system (except the pick-up) is dandy fine..........<<IDK anything about the Pertronix>>
To test the pick-up only, all you gotta do is pass something made of iron across the pole-piece in either direction which should then send a spark ; a screwdriver works.
You can test your entire ignition system, by removing the cap and wires, taking the Distributor out but leaving the pick-up connected, near-ground the coil wire, turn the key to run, and just manually spinning the drive, in the correct direction. a stream of sparks shoud issue from the near-grounded coil-wire. You can do the same in "crank" mode , but you'll likely want to disable the starter which is easy; just pull the ground-side spade connector off the start relay; I think it's brown.
I keep a spare distributor handy for this, so I don't have to pull the D. In less than two minutes I can know everything I need to know.
The Mopar pick-up is directional. There is one for CW rotation and another for CCW. They have different colored wires. IIRC, the SBM one has one Orange wire, and the other a Grey one, or at least NOT Orange, lol.

Again; <<IDK anything about the Pertronix>>
 
the reluctor is marked for BB or SB as the rotation is different on each. if it was reversed you would have spark when you did not want it and it might be when the rotor is not pointing at a post
 
From the OPs description the engine rotates freely from the starter but with all spark plugs in and connected he gets a pushback and a pop out of the carb. the pushback seems more like a cylinder firing way too early and the pop out the carb is another clue that the spark is happening when an intake valve is open.


I wish the OP would answer some of the questions I have asked. The answers help guide to a solution.

  1. When cranking from the relay is the key in the run position? (car will only start if the key is in the run position when cranking from the starter relay, and it might not start if there is too low a voltage to the coil due to no bypass on the IGN2 cir)
  2. Was the key in the off position when it cranks freely from the starter relay with a plug out?
  3. How do you know that the distributer is timed properly?
  4. Was the dist pulled to install the protronix?
  5. Is the firing order rotation direction correct? BB rotates CCW, SB rotates CW
  6. is there 12V (nominal) on the ignition side of the Ballast with the key in the run position
  7. Is there less than 12V on the coil side of the ballast with the key in the run position (6-10V)
  8. is there cranking battery voltage to the coil side of the ballast while cranking (cranking battery voltage will be less than battery voltage because of the load of the starter, might be as low as 10V)
  9. did you follow the Protronix wiring diagrams and instructions
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Best way to verify proper sparking is to remove the distributor and spin it by hand with key in "run" and viewing for spark on a "spark tester". Best to wire from the coil HV wire straight to the tester, which can be a spark plug with its body grounded to BATT- or just the metal wire tip held close to a bare bolt on the engine. As a further "bench test", flash a timing lamp (pickup clamped over HV wire) at the distributor's reluctor wheel (distributor cap off). You should see the pickup teeth aligned when it flashes. BTW, same basic checks if changing to a GM HEI module, especially to check the polarity of the pickup wires is correct. For those w/ an old points distributor, ground the body of the distributor with a jumper wire.

I wonder if you can view the "pickup teeth" (or such) in a Pertronix under-cap. Perhaps they are nice enough to provide alignment marks. Going even further, some people drill a hole in an old distributor cap at tower #1 to verify w/ timing lamp that the spark occurs when the rotor tip aligns with the tower, termed "phasing". Of course you need to have the engine running, or at least cranking, to verify this. Chevy guys can even buy a transparent cap. You can find youtubes for most of this.

As 67Dart273 stated, also check that the Pertronix gets IGN power both with key in "crank" and in "run". That is a common issue when retrofitting, and even in the OE ignition if the ballast resistor gets broken.
 
67Dart273 said:
Get a multimeter. Connect to the coil + and ground. Since you have the resistor bypassed, turn the key to "run" and you should have very close to "same as battery."

Twist the key to start and read meter while cranking. Once again you should have very close to "same as battery."

Connect meter to battery. Turn key to run. Note reading at battery, then crank and read meter while cranking, and again note meter reading

Unless you have upgraded the wiring, ALL these girls have some wiring voltage drop. If the readings between battery and coil are more than 1/2V apart you need to dig in.

Post results here.
Click to expand...
11.7v at coil +
12.3v at battery

8.5v at coil + while cranking from key
10.7v at batt while cranking from key
 
Dana67Dart said:
From the OPs description the engine rotates freely from the starter but with all spark plugs in and connected he gets a pushback and a pop out of the carb. the pushback seems more like a cylinder firing way too early and the pop out the carb is another clue that the spark is happening when an intake valve is open.


I wish the OP would answer some of the questions I have asked. The answers help guide to a solution.

  1. When cranking from the relay is the key in the run position? (car will only start if the key is in the run position when cranking from the starter relay, and it might not start if there is too low a voltage to the coil due to no bypass on the IGN2 cir)
  2. Was the key in the off position when it cranks freely from the starter relay with a plug out?
  3. How do you know that the distributer is timed properly?
  4. Was the dist pulled to install the protronix?
  5. Is the firing order rotation direction correct? BB rotates CCW, SB rotates CW
  6. is there 12V (nominal) on the ignition side of the Ballast with the key in the run position
  7. Is there less than 12V on the coil side of the ballast with the key in the run position (6-10V)
  8. is there cranking battery voltage to the coil side of the ballast while cranking (cranking battery voltage will be less than battery voltage because of the load of the starter, might be as low as 10V)
  9. did you follow the Protronix wiring diagrams and instructions
View attachment 1716034783

View attachment 1716034786

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Click to expand...

1. Yes the key is in run position
2. No
3. I don’t know if it is timed properly
4. Dist wasn’t pulled
5. It rotates clockwise
6. I bypassed the ballast
8. Just checked cranking voltage at battery and it drops to 10.7v
9. Yes I followed the instructions and double checked at it is installed correctly.
 
All,

I have noticed that it only feels bound up after I try to add gas to the carb. This afternoon after having it sit all night I cranked from key and it cranked just fine, after I added gas to see if it would fire it started acting up.

Heading to the auto store to get a piston stop now to check TDC.
 
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