Ignition help - no spark

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Slant6power

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Hello all. I recently purchased a 74 Duster slant 6 that hasn't been started in 14 years. I replaced all ignition components (except ignition switch and starter) and still have no spark. engine cranks kind of slow as well. I did have a little spark last week and it seemed like it might start, but now nothing. Will dist. p/u not gapped properly cause no spark?
I am at a loss at this point, so any suggestions would be greatly appreciated. Thanks!
 
Slant6power said:
Hello all. I recently purchased a 74 Duster slant 6 that hasn't been started in 14 years. I replaced all ignition components (except ignition switch and starter) and still have no spark. engine cranks kind of slow as well. I did have a little spark last week and it seemed like it might start, but now nothing. Will dist. p/u not gapped properly cause no spark?
I am at a loss at this point, so any suggestions would be greatly appreciated. Thanks!
Click to expand...

Yes, the reluctor gap is important.
You can temp jump a wire from the battery pos to the coil pos and check it that way to see if you have spark.
This tells you the components are good.
Then you can work your way through the ignition system to find the problem.

Make sure the ignition box is well grounded also, because it won't fire unless it is.
 
I tried the jump wire, but still no spark. In fact I've tried every suggestion I have read to no avail. With ignition on, I have 4.5 volts at the positive side of coil and 1.2 on the negative (shouldn't be any there right?) I have sanded to bare metal behind the ignition box.
 
Disconnect the coil wire from the distributor cap And put it near a gound. Disconnect the 2 pin connector from the distributor. Turn the ignition on, get a piece of wire and short across the 2 pin connector (the side that goes to the ignition box not the distributor). Now remove the wire and you should see a spark from the coil. If you see a spark the problem is in the distributor. Hope this helps.
 
Did you replace the points and condenser? If so did you set the points cap correctly?
 
Cranks kinda slow, too.
Well if battery voltage falls too low......or battery connections are sub-par....Hmmm, I wonder? If you fix the slow cranking, the spark may fix itself. Especially since you say it did have spark last week.
 
AJ/FormS said:
Cranks kinda slow, too.
Well if battery voltage falls too low......or battery connections are sub-par....Hmmm, I wonder? If you fix the slow cranking, the spark may fix itself. Especially since you say it did have spark last week.
Click to expand...

That right there was one of the things I didn't like about Mopars and the ballast system ignition, and that was one of the main motivators behind the HEI swaps.
They solve that problem immediately.
 
First thing to check on any vehicle is do you have a good 12 volt source? If no, than fix that first.
 
I have a new battery (And everything else!) But still nothing. The only spark I got was a yellow spark as I turned off the key. Starter sound bad, so it may be partial problem.
Two things I noticed... 1 a lot of play in distributor where ignition pickup sets, making it hard to adjust air gap (when tooth goes nr pickup the magnet pulls it againt it. And 2 on the back of alternator there are 2 wires marked fld. Does it matter whch wire goes where? One has voltage. Thanks for any help or suggestions, I'm about ready to dump this car out of frustration.
 
Well, Thats the magic statement right there: I got a spark when I turned it off. That means; A) the ECU is alive, and B) the coil is working, and C) all the primary wiring is good. So now, the number one thing is this; is your brand new battery any good. Second is are your connections good; to/from the battery?, to the start relay?, to the starter?, ground returns? Is your starting system still suffering with slow cranking?
- All these questions lead to this; If during cranking, the battery voltage falls too low,below about 9vdc, the ECU may not trigger the coil.
-Say you have a bad starter, which pulls the voltage down to 9volts or less, or a weak battery, or a discharged new battery, or poor connections, etc, or any combo of things which result in the low cranking voltage. That could be your problem.
-Now on the off chance that your cranking voltage is not in the basement, try part 2 of the spark test that you already started.With the coil wire removed from the cap and air-gapped to ground about 1/4 inch or so, again prove the ECU by cycling the key on/off. Each time the key goes to off you should see the one spark.same as before.Are you good? if yes part 2 is crank it for just a couple of seconds. The coil should be shooting a river of sparks.If it is streaming sparks, that proves the distributer shaft is turning, the trigger is working, and if your no start problem is ignition related, then the problem is somewhere in the cap/rotor/wires, or plugs. Now if it isnt streaming sparks, you have to add the trigger and dist shaft to the list.And quite possibly the dual ballast resistor.Although I have never seen an ECU successfully do the key-off,one-spark test with a bad resistor block.
If your system passes all above tests, then your no-start is not an ignition problem.
In my experience the reluctor gap is not critical.If it falls between 0 and .020, it will trigger the ECU. A gap around .011 is pretty good and is set with a non-metalic feeler gauge, usually brass.Otherwise you get the problem you experienced. Im not saying it cant happen, just that I havent seen a sloppy upper end in the electronic dizzy cause a no-start.
-The two small wires on the back of the alternator; blue and green, dont care which F terminal they go on.The blue wire brings battery voltage through the ignition switch. the green returns it to the regulator. The engine will start/run just fine with them disconnected, at least for a while.
 
I recommend getting one of these.
IIRC it was $5 at O'Reiley's.

Makes cheeking a HELL of a lot easier.

Plug wire positively snaps on, and I use the shock tower as a ground.

Distributor wire will slide on loose, but weight will usually allow a good contact to check the coil as well.

I like this style MUCH better than the style with a light bulb.

I'm going through the same issue on my latest /6 parts car.

Something in the points distributor was wacked, despite it passing every test I did.
Wasn't telling coil to fire.

I just got a JY electronic dist, and wired that up.
Now the coil is firing, and after replacing a third cap, at least one plug is firing.

It's fighting me every step of the way, but I'm making progress.
 

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To YY1
Well, if by shock tower, you mean the upper end of the shock-stud, as a ground, that may not be the best idea. Both ends of the shock are rubber isolated from the chassis.While its possible for the shock to ground at the bottom end, its not all that likely. A way better idea is to find something on the engine.
And yes, that tool is handy.
 
AJ/FormS said:
Well, Thats the magic statement right there: I got a spark when I turned it off. That means; A) the ECU is alive, and B) the coil is working, and C) all the primary wiring is good. So now, the number one thing is this; is your brand new battery any good. Second is are your connections good; to/from the battery?, to the start relay?, to the starter?, ground returns? Is your starting system still suffering with slow cranking?
- All these questions lead to this; If during cranking, the battery voltage falls too low,below about 9vdc, the ECU may not trigger the coil.
-Say you have a bad starter, which pulls the voltage down to 9volts or less, or a weak battery, or a discharged new battery, or poor connections, etc, or any combo of things which result in the low cranking voltage. That could be your problem.
-Now on the off chance that your cranking voltage is not in the basement, try part 2 of the spark test that you already started.With the coil wire removed from the cap and air-gapped to ground about 1/4 inch or so, again prove the ECU by cycling the key on/off. Each time the key goes to off you should see the one spark.same as before.Are you good? if yes part 2 is crank it for just a couple of seconds. The coil should be shooting a river of sparks.If it is streaming sparks, that proves the distributer shaft is turning, the trigger is working, and if your no start problem is ignition related, then the problem is somewhere in the cap/rotor/wires, or plugs. Now if it isnt streaming sparks, you have to add the trigger and dist shaft to the list.And quite possibly the dual ballast resistor.Although I have never seen an ECU successfully do the key-off,one-spark test with a bad resistor block.
If your system passes all above tests, then your no-start is not an ignition problem.
In my experience the reluctor gap is not critical.If it falls between 0 and .020, it will trigger the ECU. A gap around .011 is pretty good and is set with a non-metalic feeler gauge, usually brass.Otherwise you get the problem you experienced. Im not saying it cant happen, just that I havent seen a sloppy upper end in the electronic dizzy cause a no-start.
-The two small wires on the back of the alternator; blue and green, dont care which F terminal they go on.The blue wire brings battery voltage through the ignition switch. the green returns it to the regulator. The engine will start/run just fine with them disconnected, at least for a while.
Click to expand...


Thanks very much for the great info!
I will go back thru the system. Pulled the starter, taking to get tested. Recharging the new battery to be sure it's all there. Hopefully I see progress soon.
Thanks again!
 
I know that, but it was close, and fit the alligator clip well.

To my surprise, it sparked, so I'm still using it.
 
YY1 said:
I recommend getting one of these.
IIRC it was $5 at O'Reiley's.

Makes cheeking a HELL of a lot easier.

Plug wire positively snaps on, and I use the shock tower as a ground.

Distributor wire will slide on loose, but weight will usually allow a good contact to check the coil as well.

I like this style MUCH better than the style with a light bulb.

I'm going through the same issue on my latest /6 parts car.

Something in the points distributor was wacked, despite it passing every test I did.
Wasn't telling coil to fire.

I just got a JY electronic dist, and wired that up.
Now the coil is firing, and after replacing a third cap, at least one plug is firing.

It's fighting me every step of the way, but I'm making progress.
Click to expand...


Thanks, I will get one of those. Good luck on your project as well.
 
To YY1
Well I can find my way to the toilet in the dark.But I prefer to turn on a light.
If you choose to continue to use that source as ground, you sure wont get any help from me.
 
Slant6power said:
Will dist. p/u not gapped properly cause no spark?
Click to expand...


FYI: The distributor reluctor gap will allow the car to start cold, but not hot when at .030".... (I know from experience...) I found the "grey area" by accident by not checking a new distributor once.... Don't assume a brand new MP distributor has the gap set correctly.... :???:


It should be set to .007" - .008" with a brass feeler gauge. :D
 
When you check the reluctor gap, you need to do it with a non-magnetic feeler or paper of the right thickness; a steel feeler gage can mess up the pick-up or the wheel.
 
Hence I said "brass" feeler gauge... (non magnetic)
 
krazykuda said:
FYI: The distributor reluctor gap will allow the car to start cold, but not hot when at .030".... (I know from experience...) I found the "grey area" by accident by not checking a new distributor once.... Don't assume a brand new MP distributor has the gap set correctly.... :???:


It should be set to .007" - .008" with a brass feeler gauge. :D
Click to expand...
We were writing at the same time....LOL. And I just popped in to say what you just said about running cold with a wide gap but not being able to run or fire warm; the sensor sensitivity goes down when hot (A LOT).
 
Slant6power said:
I tried the jump wire, but still no spark. In fact I've tried every suggestion I have read to no avail. With ignition on, I have 4.5 volts at the positive side of coil and 1.2 on the negative (shouldn't be any there right?) I have sanded to bare metal behind the ignition box.
Click to expand...
When you made these measurement, was the ignition in RUN? 4.5v is too low; shoudl be closer to 8-9 volts. Do this again, and check the voltage on the blue wire into the ballast resistor under the same conditions and let us know waht you measure at all 3 points.

Also, please confirm that this car has a dual ballast resistor with 4 terminals. There is a high resistance side to that part and a low resistance side.

Refer to a similar thread at this time in this forum.
http://www.forabodiesonly.com/mopar/showthread.php?t=304276
It turned out that the connections to the dual ballast resistors in that fellow's car were reversed. That put the high resistance side of the dual ballast in series with the coil and killed spark.
 
I finally got my Duster started after 14 years sitting. Now... about that knocking noise. When I rev above idle there is a kind of knocking noise. Could this be from timing off (had dist out and eyeballed it back in (no timing light), or is the engine about to go? Thermostat area was completely clogged with powdery substance (outside of engine) so water was stuck in motor.
 
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