Can Not Figure Out Why No Spark at Plugs

[Kern Dog]

SOME people thought that I am the OP.
I am not. I chimed in to provide help. ONE member didn't, instead he decided to just chatter.
Look at post # 4, then 5.
SOME people think that they can dictate how the OP or others treat their cars.
These cars often sit awhile between uses. Sometimes stuff happens and we have to fix it to be able to drive the car.
For example...
This afternoon I went out back to start up my 72 Duster. I had ether and a battery jumper box. It was getting fuel so I assumed it wasn't starting due to the dreaded random no spark issue. You know, the only car I have here that never fails to start is the oldest and the only one with a points ignition?
My 2 '70 Chargers, the 75 Power Wagon and this 72 Duster have factory type electronic ignition and they all (except Jigsaw) have had the occasional no spark issue that often just goes away as fast as it comes along. Why is that?
The Duster had spark coming from the coil wire so the distributor was getting spark. It was dry inside. I removed the plug wire from #1 cylinder, put a loose plug in it and tested it for spark. Suddenly, it fired right up and ran on 7 cylinders. I shut it down and attached the plug wire and then it started normally.
Why? What did I change to induce it to start when it wouldn't before?
See? Weird stuff does happen and can be hard to diagnose and hard to prevent from happening in the future.

 

[kiwigtx]

SOME people thought that I am the OP.
I am not. I chimed in to provide help. ONE member didn't, instead he decided to just chatter.
Look at post # 4, then 5.
SOME people think that they can dictate how the OP or others treat their cars.
These cars often sit awhile between uses. Sometimes stuff happens and we have to fix it to be able to drive the car.
For example...
This afternoon I went out back to start up my 72 Duster. I had ether and a battery jumper box. It was getting fuel so I assumed it wasn't starting due to the dreaded random no spark issue. You know, the only car I have here that never fails to start is the oldest and the only one with a points ignition?
My 2 '70 Chargers, the 75 Power Wagon and this 72 Duster have factory type electronic ignition and they all (except Jigsaw) have had the occasional no spark issue that often just goes away as fast as it comes along. Why is that?
The Duster had spark coming from the coil wire so the distributor was getting spark. It was dry inside. I removed the plug wire from #1 cylinder, put a loose plug in it and tested it for spark. Suddenly, it fired right up and ran on 7 cylinders. I shut it down and attached the plug wire and then it started normally.
Why? What did I change to induce it to start when it wouldn't before?
See? Weird stuff does happen and can be hard to diagnose and hard to prevent from happening in the future.

Bob might come across as a tad negative, but jeez that post #18 had me laughing my *** off.

now...

No harm in having a bit of fun sometimes.

 

[Photon440]

The point of having an old car is to fix it ONCE ...then drive it and enjoy it, going to cruises or take it to the Woodward Avenue Dream Cruise.....50,000+ cruise cars, last weekend in August (google it) The OP is dealing with minutiae, like one or two distributor advance degrees is something to worry about. Or setting the reluctor pickup gap or how to set the timing ir use vacuum advance or not or how to wax the hood or how to air the tires or how to use a timing light. These things are fundamental principles....like condensation under the distributor cap...dry it out and move on......if a person does not understand these aspects, perhaps they should become viewers and not participants or owners ...... just a thought......
BOB RENTON

Why so negative, Bob? Not everyone is a professional mechanic but that doesn't mean they can't ask questions. I've never had an old car that needed fixing only ONCE, sometimes unexpected problems arise, sometimes even a newer car has repeat problems. Especially with vehicles that are not daily drivers and may sit for long periods of time.

If somebody has an issue with their vehicle and have already taken the time to do some troubleshooting and provide information regarding potential problem areas that have already been addressed, and I have an idea that may help, I'll have no problem with adding my idea of where to check next. Typing a possible cause takes about the same time as typing a negative opinion.

Suggesting that because something went wrong and the solution wasn't readily apparent or understood that the person should then not participate or own a car would eliminate a lot of enthusiasts.

 

[RemCharger]

Why so negative, Bob? Not everyone is a professional mechanic

 

[Kern Dog]

I'm okay with people poking fun at me. I don't mind if the joke is based on something legitimate.
If someone makes insulting comments related to me posting too much or starting too many threads....WHY wouldn't you just IGNORE me?
Click the IGNORE option.
It costs nothing.
I'm just the guy that is curious about mechanical things and motivated to work on my cars. Join in and maybe we can learn from each other.

 

[kiwigtx]

So back to the spark plugs.....any closer to a clue on the problem? @73LemonTwist

 

[dan juhasz]

The point of having an old car is to fix it ONCE ...then drive it and enjoy it, going to cruises or take it to the Woodward Avenue Dream Cruise.....50,000+ cruise cars, last weekend in August (google it) The OP is dealing with minutiae, like one or two distributor advance degrees is something to worry about. Or setting the reluctor pickup gap or how to set the timing ir use vacuum advance or not or how to wax the hood or how to air the tires or how to use a timing light. These things are fundamental principles....like condensation under the distributor cap...dry it out and move on......if a person does not understand these aspects, perhaps they should become viewers and not participants or owners ...... just a thought......
BOB RENTON

I can’t agree with your take on it Bob. I’m always fiddling with my cars and and doing subtle things to make things better in looks or performance. Usually when I complete a car to my standard or liking I move it along and look for that next project with whatever challenges it brings.
My background is an auto mechanic. I’ve been a certified master tech with A1 advanced level for 30 plus years ( retired now) . Having said that I still find myself reaching out to the forum for advice or help if I come across a problem that I can’t solve in short order. I think that’s a big part of why this community exists. If we push away people that ask for help with what might be rudimentary issues and tell them to take it to someone who understands the systems or to sell the car is very counterproductive.
Just my 2 cents.

 

[67 Coronet Conv]

I’ve had the same problem, except my car would stall while driving. After an hour or so of sitting it would start right up. Very frustrating at times to the point of where I stoped driving the car. Thinking something was getting hot and not making a connection somewhere in the distributor, thinking reluctor gap maybe. I wanted reliability so I replaced ever single electric part forward of the firewall, alternator, voltage reg, new distributor with ECM and Coil, wire harness. Have a few items to button up on the fuel system the. I can see if this gremlin has been eliminated. Stay tuned for a report out in the future…

 

[kiwigtx]

I’ve had the same problem, except my car would stall while driving. After an hour or so of sitting it would start right up. Very frustrating at times to the point of where I stoped driving the car. Thinking something was getting hot and not making a connection somewhere in the distributor, thinking reluctor gap maybe. I wanted reliability so I replaced ever single electric part forward of the firewall, alternator, voltage reg, new distributor with ECM and Coil, wire harness. Have a few items to button up on the fuel system the. I can see if this gremlin has been eliminated. Stay tuned for a report out in the future…

I had my GTX cut out on me one day.....I pulled over and checked things over.

Found the blue wire on the ballast resistor had worked loose. Squeezed it up a bit and re-fitted.
Car started right up, and I got home fine ....replaced the connector when I got home, and it was never an issue again.

 

[73LemonTwist]

Mystery solved... I don't have an ignition problem, I have a diagnostic problem.

Fran and Photon440 - your posts pointed me in the right direction. If I know my cap and rotor are good and there is no ground there - the only route to ground has to be through the plugs.

I scored one of these inline testers and it showed me that I did in fact have spark at the plugs
https://www.princessauto.com/en/inline-ignition-spark-tester/product/PA0009154691

I have always used my timing light to tell me if I have spark. In this case that turned out to be lying to me. I borrowed two other timing lights from friends (older and non-dialback types) and they did show spark on the plug wires while cranking. Why on earth my timing light shows me spark on the coil wire, but not on the plug wires (while cranking) is beyond me.

I guess my learning to share is, when your test results don't make sense, check your test equipment - don't assume its telling the truth.

 

[Road Grabber]

Electricity follows the easiest path of resistance. The suggestion of a poor ground is a good one. Make sure your engine is grounded to the frame or body. Not just a ground cable to the engine. You should have a large cable to the engine and a pigtail heavy wire from the battery cable to the from/body. Make sure you have a clean connection and not over paint. Some people add a ground cable from the engine to the firewall too.
Make sure your wires are completely inside the cap and coil and that the crimped ends of the coil wire are contacting the center core. When people pull wires in and out troubleshooting they can loosen or move the connections.

Having said that since you are using an MSD system you could always call for tech support and get their input. Go to the source. Stock systems are not the same when it comes to random problems. Doesn’t hurt to make a phone call. They might even walk you through it or have others calling them with the same issue.

If the car ran but doesn’t run now it’s usually something simple. Don’t lose sleep over it.

 

[P Dubya]

SOME people thought that I am the OP.
I am not. I chimed in to provide help. ONE member didn't, instead he decided to just chatter.
Look at post # 4, then 5.
SOME people think that they can dictate how the OP or others treat their cars.
These cars often sit awhile between uses. Sometimes stuff happens and we have to fix it to be able to drive the car.
For example...
This afternoon I went out back to start up my 72 Duster. I had ether and a battery jumper box. It was getting fuel so I assumed it wasn't starting due to the dreaded random no spark issue. You know, the only car I have here that never fails to start is the oldest and the only one with a points ignition?
My 2 '70 Chargers, the 75 Power Wagon and this 72 Duster have factory type electronic ignition and they all (except Jigsaw) have had the occasional no spark issue that often just goes away as fast as it comes along. Why is that?
The Duster had spark coming from the coil wire so the distributor was getting spark. It was dry inside. I removed the plug wire from #1 cylinder, put a loose plug in it and tested it for spark. Suddenly, it fired right up and ran on 7 cylinders. I shut it down and attached the plug wire and then it started normally.
Why? What did I change to induce it to start when it wouldn't before?
See? Weird stuff does happen and can be hard to diagnose and hard to prevent from happening in the future.

Kern Dog.... I fought basically the very same issue with my car recently and it did nearly the exact same thing right down to starting and running on 7 cylinders and then all 8 after attaching last wire. I previously posted about this with a post titled 'Sunday and no spark' or something along those lines. What did I come up with as the cause? Well, first 'I' didn't. Lots of help from this forum and what I count to be a new friend in my contacts list on my phone.... The most likely thing that we can come up with is a loss of ground... Not sure why. I had spark from the coil to the intake one day but couldn't get spark at a plug grounded to the engine. I cranked the engine with the plug in my hand and got one helluva shock. I had become the ground... Frustrated, the car sat for a few days. When I went back to it to do more testing I went back to the coil to test for spark and had it. Held coil wire a ways out of the coil tower on the cap and was able to watch spark jump into cap. Plugged coil wire into cap and bumped starter.... Car immediately lit off on 7 cylinders!

 

[66 Sat]

Bob, I treat my car like my dick.
It might not get driven every day but I like to tinker with it so when I do take it out, it's ready to go.

 

[RJRENTON]

Bob, I treat my car like my dick.
It might not get driven every day but I like to tinker with it so when I do take it out, it's ready to go.

I thought you drove a Mopar vehicle.....but....it sounds like a FORD (Fix Or Repair Daily) ......why do you have to "tinker" with it, IF it's ready to go? Does it or something deterrioate from just bring parked??? Just curious...
BOB RENTON

 

[66 Sat]

I thought you drove a Mopar vehicle.....but....it sounds like a FORD (Fix Or Repair Daily) ......why do you have to "tinker" with it, IF it's ready to go? Does it or something deterrioate from just bring parked??? Just curious...
BOB RENTON

I use a formula that you may be familiar with or maybe even wrote:

Where F = How fast I want to go today, K = Carburetor cfm, D = Initial Timing, and R = How many cups of coffee I've had

 

[RJRENTON]

I use a formula that you may be familiar with or maybe even wrote:
View attachment 1650209
Where F = How fast I want to go today, K = Carburetor cfm, D = Initial Timing, and R = How many cups of coffee I've had

Fairly impressive...but....you forgot to include the 4th power of the definite integral with the min-max boundaries, including the PI constraints. In the second iteration, the inverted function is incorrectly stated. Should be positive. Perhaps greater accuracy could be attained if converted to the INDEFINITE INTEGRAL.....just a thought
BOB RENTON

 

[Kern Dog]

I use a formula that you may be familiar with or maybe even wrote:
View attachment 1650209
Where F = How fast I want to go today, K = Carburetor cfm, D = Initial Timing, and R = How many cups of coffee I've had

That is some funny ****.
Some engineers complicate even the simplest things, making them a bigger problem than they really are.
Some are better “ grounded”, (so to speak) and are actually practical thinkers.
I respect the members that take the time to offer help but when a guy asks what time it is, you shouldn’t tell him how a watch is built, the processes involved in the manufacturing of it, the metallurgy of the components or the unit costs of the watch…. Just tell the man what time it is.

 

[kiwigtx]

I use a formula that you may be familiar with or maybe even wrote:
View attachment 1650209
Where F = How fast I want to go today, K = Carburetor cfm, D = Initial Timing, and R = How many cups of coffee I've had

That's a step or two more difficult than the quadratic equations I had to solve in High School.

 

[RemCharger]

That is some funny ****.
Some engineers complicate even the simplest things, making them a bigger problem than they really are.
Some are better “ grounded”, (so to speak) and are actually practical thinkers.
I respect the members that take the time to offer help but when a guy asks what time it is, you shouldn’t tell him how a watch is built, the processes involved in the manufacturing of it, the metallurgy of the components or the unit costs of the watch…. Just tell the man what time it is.

But if the guy genuinely doesn't know what time it is.. divert and distract.

 

[Bee1971]

Bob, I treat my car like my dick.
It might not get driven every day but I like to tinker with it so when I do take it out, it's ready to go.

I thought you drove a Mopar vehicle.....but....it sounds like a FORD (Fix Or Repair Daily) ......why do you have to "tinker" with it, IF it's ready to go? Does it or something deterrioate from just bring parked??? Just curious...
BOB RENTON

Sunday AM

Should I Laugh , or should I Cry

Both