Hey all, needing help with my 1973 Dodge Dart Sport. While driving yesterday the engine lost all power. The engine turns over fine, carb getting plenty of fuel, new coil, new alternator. Not sure what it could be maybe something with the distirbutor or electrical since it doesnt appear to be getting any spark. Any ideas.
Thanks
DJ

 

Try a new ballast resister.

 

the one that bites a lot of people in the *** is the pick up / reluctor gap inside the dist , it should be .008

 

"Doesn't appear" to be getting any spark.

You should be able to CONFIRM, so how did you check spark?

It is important to realize that the ignition power from the switch is DIFFERENT in start and run, and that testing for spark while jumpering around the start relay changes things.

That is, in "start" using the key, the IGN2 (brown) circuit jumpers direct battery voltage to the coil, giving you a stronger spark for starting.

But testing for spark while jumpering the relay allows the "run" wire (dark blue) from the IGN switch to be engaged, and runs through the ballast resistor, giving you a very weak spark because when cranking, the battery pulls down the voltage.

SO

TO check spark, you either need to rig a spark gap/ spark tester which you can see while engaging the key to start, or use two people.

OR you can jumper a clip lead from a battery source (starter relay stud) to the coil + terminal, and then jumper around the start relay. This is good and bad -- it directly powers the ign system, but also cuts out the ignition switch, so if the switch, the ballast resistor, or bulkhead connector terminals are the problem you will get a nice spark.

Get a multimeter. Turn the key to "run" engine off. If you cannot identify which ballast resistor terminal is from the switch, it is the one with the highest voltage reading. This reading should be "same as battery."

Next, clip your meter to coil + and crank the engine USING THE KEY. You should see more that 10.5V and in no case below 10. The higher the better

If the car does not fire on the key and then die when the key is released, it PROBABLY is not the ballast resistor.

Unbolt the ECU, clean the mount and firewall and remount using star washers. While you are at it, do the same with the voltage regulator. THEY MUST be grounded

Remove the ballest connectors, the ECU connector and the distributor connector, and work them in / out several times to scrub the terminals clean, and "feel" for tightness. Inspect them for corrosion

Remove the cap and carefully inspect the cap and rotor for damage, carbon tracking, cracks, moisture or other dirt// debri. Inspect the pickup and reluctor for rust, debri, and strike damage. Go pick up a .008" (inches not mm) BRASS feeler and check the reluctor to pickup gap. O'Reallys had these last I needed one.

Hook your multimeter on low AC (NOT DC) volts to the distributor connector. Crank the engine and read, it should generate about 1V AC while cranking.

If none of this results in spark, check the pickup coil or replace it, and if not, replace the coil or ECU. It's a tossup. You can check the coil for continuity, but that's no guarantee the coil actually works.

With all wires disconnected from the coil NO coil terminal should show continuity to ground.

Neg terminal to Pos. terminal should be a low resistance, and will depend on what coil you have, anywhere from 1? to 5? ohms, and this also depends on the accuracy of your meter.

Neg terminal to the high tension terminal will be several "K" ohms, 10-15K or 10-15 thousand ohms This reading also depends on what you have for a coil.

IF you don't have a shop manual, you should get one.

 

Put a timing light on it . Check the timing to see if the chain jumped. Check to see if the e distributor is turning

 

Ballast Resistor it was... a $4 part available at Autozone............

Thanks Bremer and everyone who gave me suggestions..........

 

I carry an extra resistor with me along with tools to change it.

 

I wonder how often the ballasts go out..Maybe I should stockpile a few while they are still readily available

 

Dj - It's rare but does happen. Yes, keep a spare resistor in your glove box or trunk tool kit. Since you hand an immediate failure, you did right by the A F S method, (Air, Fuel, Spark). Next go to the most obvious before looking at the more esoteric. Remember, these engines are pretty darn simple when you think about it. Archer

 

Use that big thumb on the right for me.

 

check th dist gap anyway , often they are not set even close to where they should be , carrying a spare ballast is just part of owning an old Mopar !!

 

Part of the ballast failure problem MAY be due to the modern poor quality of 3rd world import parts

Other things are

Is the battery showing signs of overcharge, or do you ever actually check battery charging voltage?

You ever leave the key on with engine off?

"Hot" non factory coils

Water, either from leakage or washing down the engine bay, can crack/ damage the ceramic, even in the back, and cause thermal stress and lead to failure

The GOOD news

I often wonder, if these systems were correctly installed, IE as per factory, proper coil, etc, just how many failures there would be, or how many there actually ARE

I've junked out several Mopars, and you could tell by the grease/ dirt that the still good ballast had been there for a very long time

In my own case, I've owned several Mopars over the years, and have not replaced more than two or three ballasts in all that time. May have been only two.

My first breakerless Mopar system was one a guy jerked out of a 73-4 and he converted to points. This was about 73-4 I bought the harness, dist, and ECU from him for a dance, not even a song, and strapped it immediately into my 70 RR which had a 340 at the time. I ran that until I sold it around 78?? or so.