No spark from coil???

-
H

hoop

Well-Known Member
Joined
Jan 24, 2012
Messages
242
Reaction score
16
Location
Kentucky 40862
My 72 Dart with electronic ignition, turns over, but will not start, no spark from coil wire plug, on + side wire it has 10.75v, on ballast resistor I got 2.1ohms & timp outside when tested was 96 deg. so don't know why I'm getting no spark???
 
+ side of "what" and under what conditions?

Turn key to "run". Measure coil + to ground and coil NEG to ground and post back

Make certain ECU is grounded.

Again with key "in run" disconnect the distributor connector, and take up the engine bay harness side of the connector. Tap the bare end of the connnector to ground, each time should make one single "snap" spark

Hook meter to coil + and crank engine, read meter while cranking. Post back.

Inspect interior of distributor, for debri, shaft wobble, and strike damage on reluctor/ pickup

Hook your meter to the two distributor connector terminals. Crank the engine and read the meter on AC --that's right AC volts. It should generate about 1V AC

"Wiggle" test all the connectors. Remove and work in/ out the ECU connector, ballast connector, and MOST especially the distributor connector

When you get time run down to the parts store and pickup a .008" (inches) brass feeler gauge. This is the gap you need between the reluctor and pickup
 
Here's a post I made about the simplest way I know to get across testing the ECU/ ignition parts

You need a coil, the ECU and the distributor

Lay it out on the bench. Follow the diagram. Find the two distributor pickup terminals on the ECU. Hook them to the distributor

Hook the ECU case to battery NEG

Coil does NOT need grounded

Distributor does NOT need grounded.

Hook coil + to the power lead terminal on the ECU. Get a clip lead hooked there and let dangle. This is your battery "hot" when you are ready

Hook something from coil "case" to a probe for testing spark.

Hook up your power clip lead. Twist the distributor shaft while holding the test probe near the coil tower. The thing should make sparks

If not, unhook distributor. Take first one, then the other pickup clip leads, and "tap tap" ground them at the battery connection. Coil should make 1 spark each time you do so.

If not, try another coil. If that does not fix it replace the ECU

IF you hook it all up and it WORKS, then there is something AFU in the car harness. SUSPECT a bad ECU connector OR a bad DISTRIBUTOR connector
=============================================
This is all you need to test the basics of the ignition. You can easily test the ballast separate. A battery, the ECU, distributor and a coil, and of course some test leads

2ai0wsj.jpg


Below, the basic diagram for a 4 pin ECU

166lmj7.jpg


Below, the wire for testing spark. I use my 12V test light. No, LOL the spark won't blow up the bulb

166lmj7.jpg


Below, the ground connection. ALL you need is one wire from batt NEG to the ECU case

xawjl.jpg


Below, the two distributor connections. In the car these are polarity sensitive, but for testing does not matter

b3opvm.jpg


Below, the coil NEG connection

6jfywp.jpg


Below, battery PLUS connection, one wire to this terminal of ECU and jumpered over to + side of coil


11lqu5l.jpg


Below, all hooked up and ready to test (except for battery ground). Should produce sparks at least 3/8" and typically 1/2" long

1zzoya0.jpg


Below, distributor "one wire" test. I have removed the other distributor wire for simplicity. Take the bare connector end or this clip lead (the yellow) and with everything hooked up, ground it repeatedly. Each grounding should result in a spark (In this photo you need to hook up the ECU ground wire, I left it off for the photo)

vgitld.jpg
 
hoop said:
My 72 Dart with electronic ignition, turns over, but will not start, no spark from coil wire plug, on + side wire it has 10.75v, on ballast resistor I got 2.1ohms & timp outside when tested was 96 deg. so don't know why I'm getting no spark???
Click to expand...
O its a 318 also!
 
67Dart273 said:
+ side of "what" and under what conditions?

Turn key to "run". Measure coil + to ground and coil NEG to ground and post back

Make certain ECU is grounded.

Again with key "in run" disconnect the distributor connector, and take up the engine bay harness side of the connector. Tap the bare end of the connnector to ground, each time should make one single "snap" spark

Hook meter to coil + and crank engine, read meter while cranking. Post back.

Inspect interior of distributor, for debri, shaft wobble, and strike damage on reluctor/ pickup

Hook your meter to the two distributor connector terminals. Crank the engine and read the meter on AC --that's right AC volts. It should generate about 1V AC

"Wiggle" test all the connectors. Remove and work in/ out the ECU connector, ballast connector, and MOST especially the distributor connector

When you get time run down to the parts store and pickup a .008" (inches) brass feeler gauge. This is the gap you need between the reluctor and pickup
Click to expand...

+ side of coil!
 
I forgot to put when testing power on + side coil wire, key was in on, at + wire 10.75v, battery was just a little lower at 12.26v. So is thats what you should be getting to coil?
 
hoop said:
My 72 Dart with electronic ignition, turns over, but will not start, no spark from coil wire plug, on + side wire it has 10.75v, on ballast resistor I got 2.1ohms & timp outside when tested was 96 deg. so don't know why I'm getting no spark???
Click to expand...
forgot to put, I did try a used good coil from a /6 car, steel did not start, tested for spark from coil, steel no spark, tested for ohms on premier & security of coil on my car, it did have ohm on both!
 
hoop said:
I forgot to put when testing power on + side coil wire, key was in on, at + wire 10.75v, battery was just a little lower at 12.26v. So is thats what you should be getting to coil?
Click to expand...


Well you didn't fully answer the question but that's close enough

With the battery at 12.2 (OK) and the key in "run" you are going through the ballast to the coil. If the ECU is causing the coil to draw current (it should) the coil + will be considerably below the battery

So far so good.

Did you try tapping the distributor pickup test? Re-read above
 
There is an air gap between the rotor and pickup, in the distributor, it needs to be set at .004" If the g is wider than that, no spark. The gap widens as the distributor gets warm, so sometimes you'll get a car that will start cold but not hot.
 
I did try another pickup coil from another disturber I had put up that was out of a 74 scamp, but steal would not start & took coil wire loose, put it close something metal, steal no spark!
 
hoop said:
My red repair book says .008 on gap for electronic ignition!
Click to expand...

Yep, Joe is rightish and your red book is right.

The most common causes of ignition problems are these:

  • Poor ECU grounding
  • Distributor pick-up coil gap too wide
  • Distributor pick-up coil failure (often intermittently)
  • Ballast resistor failure
  • ECU failure
  • Poor connection (wiring issue)

^^^^These are the top six, IMO. Start at the top and work down. Yes coils do fail, but they don't make the top six :)

Good luck!
 
It was the ECU, got a cheep blue box from autozone, put it on & it started right up!.. later on I'll get me a mopar orange box back & keep the blue one for a back up!
 
You must log in or register to reply here.
-

Back
Top