I have a 71 dart with a 440 factory electronic igination.when i turn the key on i get spark.i will lose spark when the engine is tryin to start.when i let go of the key i kinda have spark again. Possibly the ignition switch or coil?

Ballast resistor sounds like perhaps..

It sounds like one of two things, loose or dirty connection on the ballast resistor or a wiring problem from the ignition switch to the ballast resistor.
Someone put that motor and ignition in that car, check all the connection closely first and then use a volt meter to check the voltage (check the voltage at the battery first, if it is around 12.6 volts) to both ends of the ballast resistor, you should have almost the same voltage,12.4 to 12.6 V, at the ballast on one end and around 6.0 to 8.5 volts to the other end with the key on and the engine not running Next thing is to put the shifter in some gear position other than neutral or park and have a helper turn the ignition switch to the start position while you check the end of the ballast resistor that had the lower voltage with the key on, it should increase to battery voltage or a tiny bit less in the start position to that end of the ballast resistor to make the coil fire when in the start position
Mopar electrical engineers made it harder on us to trouble shoot problems in their design of theses cars
Let us know what you find and have to do to fix it, that will help others on here later

check the air gap on the distributor also...

5 pin/4 terminal "dual" ballast system or 4 pin/2 terminal "single" ballast system? As said: bad box/open in ballast/too much reluctor gap

Since the ballast is bypassed in start and he's only getting spark in run I seriously doubt it's the ballast resistor.

Since you get a spark at all I doubt it is the coil.

Since the ignition switch is what bypasses the ballast I suspect that or the wiring/connectors.

Crusty wiring at bulkhead etc. Bad ign switch, doubtful.

I had that exact same symptom once & it was either the box or the ballast I can't remember which

Wiring is new

11 out of 10 times it's the ballast resistor...

in that case definitely pay attention to ign1 and ign2.
one is hot when ign is in start, the other hot while ign is in run. they both need to go to...the coil...or the ign box (in my case my msd) or wherever depending on yr ignition setup. look at a schematic.

OK guys..... look at the original post. If I'm reading it correctly, then he has spark at "run", but no spark at "start" position of the key.

This is the OPPOSITE of the typical ballast resistor burning out. If I'm reading that correctly, then there's either a problem with the brown wire coming out of the bulkhead disconnect (the one that bypasses the ballast resistor) or the ignition switch itself.

One way to test this would be to run a jumper wire from the + of the battery to the disconnected ballast resistor plug that has the brown wire. If the car starts & stays running, then you've found the problem. Don't just leave that wire hooked up though since your ignition voltage is supposed to be "stepped down" with the ballast resistor during normal running & this jumper wire isn't going through the ballast resistor.

put it in run and then jump the starter relay.
if it starts, you have a circuit problem.
if it doesn't then the computer probably has an issue.

You mean the ignition box? 71 dart doesnt have a computer.

sure. same thing to me. electronic part.

if the key movement is allowing something to happen in the box even though it isn't working, then you won't be able to start the car by bridging the start relay.

if it does start then you have an issue with the circuit that should power the coil/spark box when in start.

it should be pretty quick to see which.

The ECU doesn't care if the key is in run or start, it is powered the same regardless. What is powered differently is the coil. So, if the ECU makes a spark at all it is working.

sure, but my statement is still good.
if he can start it in run then there is a circuit issue.
if he cannot, then maybe it isn't the ecu, but something died and has to be replaced.
it narrows down this chase.

Rarely a starter can have so much drag or a very poor starter cable or connection can suck all the amps out of a battery, there is nothing left over for the coil to fire off the engine.

However when you release the key, all the battery's pent up energy can be diverted to the coil and either succeed or try to anyway fire off the still rotating engine.

Unlikely, however at times when you hear hoofbeats, it really may be a Zebra and not a Horse.

Run a jumper from battery positive to coil positive, bypassing everything in wiring that is the more likely problem. If starts, work backward toward ignition switch thru all wiring and connectors. My money is on this or ballast.

True, but for any test to be useful you have to know what it is doing.

I'm thinking it might be hard to decipher if it is on "run" or "crank" in that split second when the key is being released from crank to run when there is the one spark. What I would do is pull the yellow wire off of the "ign" terminal on the starter relay to disable the starter (we know it cranks & no need to run the batt down for this testing) and charging the battery up with the alt causes system problems and have a helper hold the key to "crank" & see if the coil positive primary terminal and the blue/yellow ECU terminal is hot (the red/green terminal on an OE 5 pin ECU needs to be hot also) then release the key to "run" & see if everything is still hot. grab your meter.

I had the electronic ignition box tested at autozone they had a tester it came back bad.i could still test for the resistor and switch.

Progress! looking good. EDIT I'd get the new ECU in & see what happens. Standard Motor Products used to make a good American made parts house ECU but it is made in China now (iirc it is $25).

I had lifetime warranty on the ecm box.i got another one.i did more testing its failing the ability of the module to control coil and the capability of coil by actual firing.im thinking the coil is bad.

Lets do this, hook everything back up & hold the coil secondary wire (dist end) 1/4" away from the intake (ground) and with the dist pickup zigzag pull apart connector seperated, drag the male tip end of the body half across the intake surface (ground) & see if the coil wire sparks (do it with key on and with key held to start with the yellow wire terminal pulled off of the "ign" terminal on the starter relay). then reconnect the zigzag connector and remove any and all wires off of the dist neg primary post (might just be the one) and with a jumper wire connected to the coil terminal itself (not to the ring terminal you removed from it), tap tap the other alligator clip on the other end of the jumper to the intake & same thing see if the coil wire sparks (with key on & key held to crank). Holler back.

If the coil sparks it's not the coil, though I did have a coil that would intermittently fail when it got hot, but it failed in either mode. It would work when cooled off. Took awhile to sort it out but I got it.

Eventually you will have to break out a meter and find out what is going on.

I have a meter and will test the coil and see what the reading says. It was hot when the last time i tried starting it.

Try changing ECU.
It may be on its way out.

Too bad you weren't closer... I have a coil tester.

Neat tool, What is the gap when it gets to "super"? it would be a "cold" test. EDIT now I see the numbers for the gap

It actually has a "heat" setting that is used to heat the coil up before testing if wanted as well.

I don't use it often, but still a kind of cool thing to have around.

Instructions on it, if you were curious..

https://ia601209.us.archive.org/12/items/HT660/HerbrandHt-660.pdf

If you read some of the post i did.

Are you saying it sparks once when you turn the key off ? As it sounded like thats what you were saying at first ? No spark while cranking but a spark when the key is turned off ? I just want to be sure just what it is doing. Ron

I turn the key on i have spark.when i crank the key the over to start it,i loose all spark.when i let go of key i have alittle spark again.

when key is still in the on start position not run and not off.

You say you turn the key on and get spark ? Now are you jumping the starter and cranking the eng with the key on to get spark or are you saying you get a (1 Spark) spark when the key is turned on ? I ask because I have seen some throw a constant continuous spark with the key on and not cranking and also just get one spark when key turned on and then off? So I want to know if you are cranking the eng by jumping the starter and/or starter relay to crank the eng with key on and see spark ? Ron

No spark when crankin engine over.only spark is when the key is on and not crankin the engine trying to start.

I had the same problem intermittently in my Charger. Months would go by where it would be fine, then it would do the following: Crank, crank with no fire, then just as I release the key, it would snort and the engine would spin backwards a little as if it were ready to backfire. The wiring was original but in good condition.
I have a MP electronic ignition conversion in the car. I tried swapping spark boxes, coils, ballast resistors...It turned out to be in the distributor. The reluctor wheel had clocked out of phase. I repositioned it and replaced the magnetic pickup and have not had it happen again. This was almost 5 years ago.

Ok i replaced the distributor last year in it,maybe its bad again. I have replaced all those items.would fouled up spark plugs cause a no start as well?

Yeah I see the heat setting on it.

I think fouled plugs may make it harder to start, misfiring at all speeds but not a "no-start" condition unless the electrodes are burned off or there are so many deposits in there that no gap remains between the tip and electrode.

Ok now you say only spark when key is on ? Now is that just one spark when key is turned on and or off or a continuos constant spark as I have seen a bad ECU actually cause a spark that just keeps sparking with the key on and the coil wire held 1/4" away from ground. Or if its just one spark when key is turned on then off then that tells you the coil and wiring is good. And if you jump the starter and crank the eng with the key on and get no spark then it may just be a bad pick-up coil. Because if you get at least one spark when key is turned on then off it tells you the coil will fire when the primary circuit is turned off as it should. That would tell me the ECU is just not getting a signal to turn the coil primary circuit off so the magnetic field will collapse and fire in the coil secondary circuit. This is why I asked the specifics about just what is going on ?

Now if you crank the eng by jumping the starter with the key in the on posistion and get spark but get no spark when cranking the eng by the key then thats a different problem in the wiring or the ign switch ign 1 and or ign 2 circuits. Ron

Classic joke....It is lost on young guys and foreigners.

That comment is he wrote is dumb.theres other responding on tryin to tell me whats wrong.he wants to write something stupid like that.

What's wrong with a little humor in a post?

Here is how the ignition switch works on your Dart. When you turn the key to "start" the car, power is sent on the brown wire directly to the coil and bypasses the ballast. When the engine starts and you release the key, power drops off of the brown wire and the blue "run" wire powers up. If you don't have any spark while cranking,(start position)then you have a problem with the brown "start" wire.

Disconnect the yellow wire at the starter relay so the starter doesn't crank while you test. Then, starting at the ignition switch connector at the base of the steering column, test the brown wire for power when the key is held in the "start" position. You should have power on both sides of the connector. If you have power there, then test both sides of the bulkhead connector. Keep testing the brown wire all the way to the coil.

If you don't have power on the brown wire on the ignition switch side of the connector, you have a problem with the ignition switch. On my car, I had some loose connections in the ignition switch connector that I had to fix. I had power on one side of the connector but not the other.

My apologies brother & I would (likely) be the first one to complain (& I have!) if it happened to me. I would suggest trying my prior tests with it good and hot (jumper on coil neg/drag pickup body half male tip). Gotta work fast as electronic devices cool off very fast (enough to change their functioning) when dealing with heat related issues and a person can always (if it will start), let it run again till it acts up then proceed with testing.

my apology back to you with my comment i said.oh ok ill try that

with make/break grounding of the coil neg if it (coil wire) sparks in run and crank that tells you the wiring is good to that point and that the coil is OK (at least cold). then with that hooked back up. dragging the male tip of the body half of the pickup zigzag connector across the intake, if the coil wire sparks in run and crank that tells you the wiring further downstream is OK & the ECU is OK (at least cold). All that is left is the pickup (ohm it, hot and cold) and backing up a bit, the ballast can act up when heated & cause an issue in the "run" tests.

Not trying to be smart here but this makes no sense. You say................
turn the key on I have spark , when I crank the key over to start it I loose all spark , when I let go of key I have a little spark again.

OK you say when I turn key on I have spark ?? Well with the key on and not cranking the eng it wont spark so what are you saying ?? I asked do you mean when the key is turned to run you see one spark or a continuos spark ?? So just what does it do when you turn the key to run ??

You say when I crank the key to start I loose all spark so that tells us no spark while cranking.

So turn the key to run and jump the starter and crank the eng and tell us just what it does then ? If still no spark then unplug the dist pick-up and drag the male wire harness connector to ground with the key in run and see if it sparks ? If it sparks like that but no other time then heck you may just have a bad dist pick-up. Have you tested the dist pick-up. Just be sure its good before you start testing the rest of the ign circuits. If you get no spark cranking the eng then crank the eng by jumping the starter with the key in the run position and let us know if it has spark ? Ron

Ok i can try that to.correct no spark comin out of the coil wire when crankin the engine over to start.

yellow wire pulled off of the starter relay to disable the starter. A helper holding the key to "crank". You under the hood dragging the male tip of the body half of the pickup connector across the intake while holding the secondary coil wire 1/4" from ground. if it sparks the pickup is open or its 2 wire connector is open or the gap is way too far open. then with a jumper wire with alligator clips do the coil test same way (key held to start/starter disabled/coil wire 1/4" away from ground) and tap tap tap the alligator clip to ground. I would clean the ECU bottom side just to confirm a good ground but at this point in time I am leaning toward the ECU but yes I would do the tests.

Ever check the air gap on the pickup coil in the distributor?

It seemed to look ok

i replaced both the coil and electronic ignition box.it didn't fix the problem.i'm thinkin the switch is bad? it shouold be producing spark the whole time while im crankin the engine over to run.

Correct EDIT whats left is the pickup and an intermittent connection somewhere. I would make up some jumpers with alligator clips/proper as needed connectors & sub em in one circuit at a time to pin it down. keep the battery charged & even better would to elim the pickup then use a spare dist (even a /6 one) to do the triggering to save the starter/keep from running the battery down. I'm assuming the ECU has a good ground since you changed it out & on the wiring only the ECU and the coil need to be fed in ign2 and the 2 wire connector between the pickup and ECU needs continuity as does the 2 wires connecting the coil/ECU for it to fire as long as all of those are correct.

I can try that.it has to be something along those lines.again only gettin spark when turning key the over to start then nothing when continuing.It looses all the spark when trying to fire the engine. soon as i let go of key i have spark again.

you mean it kicks out 1 spark when you let off the key (to ign1 run).

Thats when i have spark again

I did not see a response to the type of ballast if its a dual sided ballast go to store pick one up, stop and get beer on way home replace ballast open beer turn key and listen to car run. on dual ballast one side handles start one handles run, start side goes bad = "crank" position on key spark will not be there but run position will be = no start with a possible spark witnessed when key returned to run position. run side goes bad= key in crank position it sparks engine fires then stalls as key is returned to run position due to no spark because of run side ballast issue. not looking to start issue but lots of time and money spent chasing ballast problems over the years by many. If it doesn't fix it I would then check bulk head connections steering column connections then triple check the new wiring but who am I anyway. I hope your drinking a beer listening to her run soon..stay at it

Contact CB Restorations in Las Vegas. He posts on Dodge Charger.com.

what I would do is with some made up jumper wires with alligator clips/specific terminals as needed I would jump from a 12V source like the batt stud on the starter relay to/thru the ballast to the coil/ECU (duplicate ALL of the ign1/ign2 circuits) & pull the ign2 wire when (if) it starts. this takes the wiring completely out of the picture & only leaves the hard components which most you have replaced then if we are good so far we can start to remove one jumper at a time & restart it to pin down which circuit has the open or intermittent connection.

Its a single its been replaced.

i did some testing with a tester,i have more spark goin to negative side of coil then positive side.which i have a very little spark on that side of coil on postive,without hotwire. when i run a hotwire from the battery post on the postive side to positive of coil i have all spark on that side and none on negative. should i have spark just on the positive side and none at negative? should have i the equal aumount on both sides? what could this problem be?

With (3) jumpers jump from the "batt" stud on the starter relay to: (1) blue/yellow terminal on the ECU pentastar connector (stick a thin/sharp pin into it) and (2) to the upstream (blue wire) end of the ballast and (3) and to the coil positive primary terminal. start it with the key & when (if) it starts then remove jumper #3. I'm assuming this is a 4 pin ECU??

Yah it is.

How come i have very weak spark on the positive side of coil? when i run a hotwire from the positive side to battery to positive of coil i have good spark goin to it.what could be bad causin very little spark to not producing continuous spark with out hotwire?

Anyone on here have a similiar problem?

You have a poor connection between the ign2 (crank) terminal on the ign switch and the coil (& maybe the ign1 "run" circuit also which is why when you bypass it with your jumper it starts. start with the bulkhead (a frequent culprit). Might be low voltage AT the ign switch (it has a connector which can be problematic but nothing like the bulkhead). A small metal bristle brush is good for the male ones and a spare male terminal for the female ones (the ones on both halves of the bulkhead). spray clean em when done. NAPA male ones are 725145 if you dont have any spare wiring/terminals laying around-99 cents ea.

Sounds like typical bad grounds.

Check battery ground to engine block and body.
Reason is, a small amount of resistance here (cable and connections) will create a large voltage drop from the block to negative battery terminal when the high current of cranking the engine goes through the cable.
Also, ground the ECU to the engine block.
With the bad grounds, the ECU will not sense the trigger voltage from the distributor.

Your sayin bulk head for the engine harness section?

Ok i do have ecm mounted to block.i have a wire goin from the inne fender where the ecm is goin to the end of engine on head.where else to check for grounds?

yes the bulkhead on the firewall that has the blue ign1 run and ign2 crank circuits.

Ok i replaced that harness it had new terminals on it.i can go back and if there is any corrosion on them etc.i have to agree that there is a poor connection and something isnt sending enough spark like you said in the previous post.

grab or make 3 jumpers & get it running (pull the one when it starts) then we can work to pin down which circuit has a bad connection & then pin down (further) where in that (particular) circuit the bad connection is.

You could pull the dist, and spin it by hand to see if you get a spark in both the start and run key positions, just disconnect the neutral safety wire from the start relay, or put trans in gear other than park or neutral so the starter does not spin when in the start key position.
If you get spark spinning the dist by hand in both positions, the problem is not the ignition or the wiring to it, but a problem with voltage drop when the starter load is applied.

If you don't get a spark spinning the dist by hand, then there is a problem in the wiring, dist pickup, or with the ECU.

^Excellent info^ EDIT & if you have another dist handy (even a /6), plug it in first & spin it for an easier start to this path.

i havent read all the posts but have you replaced the pickup coil?
i have had the spark at only key on and off syndrome and a new pickup coil cured it in a mopar and a ford.

I can try to replace the distributor again,i replaced it ounce.

What should the ohms be on the mangetic pick-up coil on the distributor?i did some testing with a ohms meter.

I found a burnt wire on distributor,took it back to autozone.goin with high performance distributor.probably will also bypass the factory electronic igination system.possibly with a msd box. the petronix igunitor type 2 or 3 good distributors?

Which wire was burnt? You might get it going with a stock dist/ECU/ballast then see if you want to upgrade. The ignitor I II and III are modules that bolt in the dist & elim the pickup/ECU/ballast. I have the I and the III (uninstalled as of yet). The I was 2 bucks at a swap meet for a Toyota & I can redrill the plate if I can get the V8 black ring with the green tape. the III I splurged on for the stock car (& my racing partner is paying for it) so I took a chance cuz it ain't my money in the hat.

Ok well im the whole distributor made by them and non vacuum advance one to.

I would (highly) suggest a vac adv unit

My 440 isnt stock its midly built,.564 high extreme energy comp cam,noisy gear drive 30 over pistons and im a runnin a 850 demon carb that doesnt have a opening for it.beefed up 906 heads with bigger intake and exhaust valves. Why you say i need one?

I'm thinking it would give a better mileage (probably not the highest on your list) and it would keep the plugs cleaner but if the demon doesn't have a ported nipple then its a moot point. EDIT might run a bit cooler (but you want no cooler than 180)