Ignition Module Issue

[7TDuster]

Good afternoon. I am in Nova Scotia, Canada and have a 70 340 Duster. Motor is a 72. I recently started having issues with no spark when the car has reached operating temperature. It will usually start right after shutting it off but after 15-30 minutes it will just continue to whirl over with no sprak then all of a sudden catch and start. I bought 2 NAPA units 3 years ago, and purchased a box this week from National Moparts in Ontario. All 3 will start the car when cold but the same issue occurs when the engine is hot. I tried an old OEM box and it starts at the touch of the key. I have replaced the coil, the ballast resistor etc and we've tried everything we can think of. My friend is a red seal mechanic and we are baffled. I put one of the boxes on the car after the car was wrmed up - the box was at ambient temperature and it wouldn't start so it's not a matter of the box getting hot.
The odds of 3 basically new - 1 a day old - being faulty are too much to think it's a box issue. The distributor is a Proform? and is about 7 years old. All under dash and engine wiring was replaced about 10 years ago and there hasn't been an issue until recently. Box, engine and body grounds are all good. My concern is that whatever is causing the issue will affect the old box that works and kill it. The back side is quite gooey.
Any ideas or suggestions of what further to check is will be greatly appreciated. Extremely frustrating.

 

[halifaxhops]

Pick up coil?

 

[mygasser]

have you pulled a plug to check for spark when it won't start? it could be fuel evaporation in the carb so the bowls have to refill before it'll start after sitting a while when hot.
neil.

 

[7TDuster]

Pick up coil?

Distributor is about the only thing we haven't checked. Have an old one that worked that we'll try.

 

[7TDuster]

have you pulled a plug to check for spark when it won't start? it could be fuel evaporation in the carb so the bowls have to refill before it'll start after sitting a while when hot.
neil.

Yes. Have done that. As well we've used an inline spark tester and nothing. All of a sudden it'll start and have a strong spark showing

 

[7TDuster]

Yes. Have done that. As well we've used an inline spark tester and nothing. All of a sudden it'll start and have a strong spark showing

Also the site glass on the carb side shows they're good

 

[Darter6]

Any ideas or suggestions of what further to check

I had a 79 doing that. The Lean Burn was replaced with the normal Mopar parts, the car would start,run and drive.But when you stopped say for gas, just crank.Try by-passing the ballast with a jumper and see what happens.Also just resent had a coil go bad on a points car. Start right up,run for a few minutes then die.
My 2 cents.

 

[DartGTDan]

A buddy's A100 pick up would do the same thing. We thought gas boiling, ballast resistor, coil, ignition module, distributor, etc... We pulled everything off of my car and put it in his truck, same scenario.

After a lot of head scratching I started chasing wires. I discovered the wiring harness to the ignition module was crushed when the previous owner installed the new engine. I replaced (cut & spliced) the wires from a new ignition module connector back to known good wire (past the crushed area). All was fine after that. What a hunt!!

 

[Dana67Dart]

After a lot of head scratching I started chasing wires

That's where I'm heading.

And the ballast resister and the ignition switch and the bulkhead connectors.

The fact that a room temp box on the hot car has the issue says it's other than the box

 

[67Dart273]

I too would "guess" the pickup coil in this case. Try to catch it when it's dead and be prepared to grab your meter and do some testing.

You need a multimeter, and a way to rig a spark gap either a plug or a gap type spark tester out of the coil tower, and using a METAL core wire, not a factory radio suppressor wire. You can use low voltage wire if you can devise a way to "hang" it in air away from metal parts.

Do testing USING THE KEY and not jumpering the start relay, as that changes the circuit

1. With key in "run" and engine stopped, measure voltage at the key side and at the coil side of the ballast, or right at the coil. Measure both sides of the coil

A...Key side of the ballast should be very close to "same as" battery voltage.

B...Coil side of ballast or coil + should be somewhat lower, and it varies. Perhaps 6--10V. This shows the coil and the box are drawing current

C...Coil NEG should be very low, the lower the better, 1 or 2V. This again shows the box is pulling the coil neg low and is drawing current

2....Rig a test gap to the coil tower. Pull the dist connector apart and take the engine bay end, NOT the coil end, and repeatedly tap the bare terminal of that connector to ground. Each tap should make a nice hot blue spark at least 3/8 and typically 1/2" long

4...Work the dist connector in/ out several times to feel for tightness and to scrub oxidation off the terminals. That connector can be troublesome. If you can round up a .17 caliber rifle bristle brush, many of them will fit inside those terminals

5...Remove dist cap and inspect, for loose bushings, shaft wobble, and rust and debri on and around the reluctor and pickup.

6...Check resistance of the pickup coil. Try to do this right away when it quits to see if you can see a problem. Actual resistance might not be important, as they changed over the years. Usually below 300 ohms or so.

7...Make absolutely certain that box is grounded. Check all connectors. If you have sharp probes, you can back probe the ECU connector to be sure it is getting power. Round up a basic diagram, so you know which ones.


CRANKING

Cranking power is a real trick. The IGN1 "run" power coming from the key GOES DEAD during cranking. The ONLY power source for ignition for starting is the IGN2 ballast bypass circuit. This comes from IGN2 on the ignition switch, is ONLY hot in "start" and feeds out to the coil + side of the ballast.

BUT IF THIS IS TRUE how does the box get power when cranking? This power feeds from the coil + "BACKWARDS" through the ballast, and backfeeds over to the ECU through the ballast resistor!!!

 

[67Dart273]

By the way I don't suppose you happen to have a breaker points distributor lying around?

If so you can use it for testing.

First, you can easily wire it without the ECU to test the wiring/ etc in the car

Second, you can wire it to the bare terminal of the pickup connector as I detailed the "tap" test, and this will eliminate the pickup coil temporarily

 

[Dan the man]

Alot of good suggestions, have you checked all of the ground wires for being tight?

 

[RustyRatRod]

Pick up coil?

Yup. That's all that's left. You get a red seal. Whatever the crap that is. lol

 

[Bewy]

But is it really an electrical problem?? The problem occurs when the engine is hot, correct? Next time it happens, remove a spark plug lead & stick a s/driver shaft in the end of the spark plug socket. Lay the shaft it on a valve cover to create a 1/4" air gap. Crank the engine to see if you get a spark.

 

[1MeanA]

Is there a ground strap on the ECU? If not I would add one...can't hurt.

 

[toolmanmike]

Is there a ground strap on the ECU? If not I would add one...can't hurt.

They do need to be grounded well like the voltage regulators. We own 50 year old cars and if those components were changed out mort than once, the so called "threads" made by the sheet metal screws are worn out. Sheet metal screws are a one time install and not made to tighten up and provide a good ground path after they have been removed and replaces numerous times.

 

[7TDuster]

I had a 79 doing that. The Lean Burn was replaced with the normal Mopar parts, the car would start,run and drive.But when you stopped say for gas, just crank.Try by-passing the ballast with a jumper and see what happens.Also just resent had a coil go bad on a points car. Start right up,run for a few minutes then die.
My 2 cents.

Thanks. We did a jumper direct to coil and no difference. New coil yesterday.
Trying different distributor today.

 

[7TDuster]

They do need to be grounded well like the voltage regulators. We own 50 year old cars and if those components were changed out mort than once, the so called "threads" made by the sheet metal screws are worn out. Sheet metal screws are a one time install and not made to tighten up and provide a good ground path after they have been removed and replaces numerous times.

Thanks. Did a really good ground and also a jumper from module direct to neg battery. No change

 

[mopar head]

Yup. That's all that's left. You get a red seal. Whatever the crap that is. lol

Old Continental industrial engines, I`m guessing modern variations still exist?

 

[7TDuster]

But is it really an electrical problem?? The problem occurs when the engine is hot, correct? Next time it happens, remove a spark plug lead & stick a s/driver shaft in the end of the spark plug socket. Lay the shaft it on a valve cover to create a 1/4" air gap. Crank the engine to see if you get a spark.

Thanks. Tried all those things. No spark then all of a sudden it'll fire.

 

[7TDuster]

Success!! Swapped out my distributor and put my old one in. Gave it a good run to warm it up. The 2 silver NAPA and the orange box all start it with a touch of the key while standing out side. This was the last thing to try but I felt because the distributor was about 7 years old it was something else. No doubt the pickup coil.
Thanks to all of you for your comments and advice. A great spot to come for technical issues.
Have a great summer everyone and stay safe!

 

[7TDuster]

Just to explain the Red Seal mechanis - which I didn't realize is just a Canadian thing -

A Red Seal mechanic is a skilled tradesperson in the automotive service technician trade who has achieved the Red Seal endorsement, signifying they have met the national standard of competency for their trade in Canada. The Red Seal endorsement, when placed on a provincial or territorial trade certificate, demonstrates that a technician is qualified to work anywhere in Canada.

 

[7TDuster]

That's where I'm heading.

And the ballast resister and the ignition switch and the bulkhead connectors.

The fact that a room temp box on the hot car has the issue says it's other than the box

We had done the bulkhead checks etc with no luck. I've noted below that problem has finally been resolved

 

[RustyRatRod]

Just to explain the Red Seal mechanis - which I didn't realize is just a Canadian thing -

A Red Seal mechanic is a skilled tradesperson in the automotive service technician trade who has achieved the Red Seal endorsement, signifying they have met the national standard of competency for their trade in Canada. The Red Seal endorsement, when placed on a provincial or territorial trade certificate, demonstrates that a technician is qualified to work anywhere in Canada.

Yeah, I figured something like that. Sorta like our ASE. I've seen lots of ASE certified "technicians" who barely knew which end of a wrench was which. Paperwork and credentials really mean nothing. Experience is the best teacher.


.....and yet he didn't know what was wrong. Gimmie my red seal. LOL

 

[Dana67Dart]

Success!! Swapped out my distributor and put my old one in

I had the same experience with a points dist.

It started misfiring then would no longer start or run

Towed the car home and after changing the likely parts I grabbed the OE side oiler point dist that had been in the rebuild's box on the shelf since the 80s. Popped it in and it fired right up.