Damn Challenger 340 need help asap!
 

Checked for spark at end of coil wire and it only sparks once! does not spark while cranking over.. what the hell is wrong here? seems like something is goofy in the ignition switch cause after cranking it and then u let off the key it sparks once again!.. please help I'm kinda a green horn when it comes to this stuff plus been away from these cars for years

Does it still have the resistor crap and regulator on the firewall? How's the voltage wire to the distributor and coil? Not the coil wire to the center of the dist. I never had the specific problem, but you know what those cars are like for electrical issues.

Grandville, i assume you check the air gap in the dist. With the key on unplug the two wire connector at the dist. Jump the two wires that go back to the harness. Every time you jump them you should get one spark. if you do then your dist pick up is bad or out of adj. If you don't get a spark let me know Tom

Tom Yes I set it at .007.. I didn't try that with the connector, but what i did do was pull the dist out of the block and with key on i spun the rotor by hand and I had the most brightest blue spark at end of coil wire!put it back in the block and it only sparks once when key is turned on then once when u turn it off.. We tried two different ballast resistors etc. it has a different ign box, the dist is new, also only getting about 9 volts to the coil. And yes Doug still has the voltage reg on firewall too.. Something is very weird with this damn car!

Maybe something is being shorted to ground when the distributor is mounted in the block?
I don't don't mean necessarily something like a pinched wire...Maybe you have a shorted ignition module or something and it's grounded through the distributor but only when bolted to the block.

Well by spinning the dist by hand you know the ECU- wiring-coil are good. even if you where off with the dist or cam gear it should still spark while cranking WTF. Get on Moparts ask if anyone lives nearby that can help,these guys are just like PY they love to help a fellow MOPAR guy. I can't see any reason why this thing won't spark.

Sounds like you don't have power to the distributor when the key is in the start position.

That's a good thought. Usually separate power paths for 'run' position and 'start' position on the switch.
If you were to turn the switch to the 'on' position and externally jump the starter or push-start (if manual tranny)...it might start.

So your sayin If I had the key to on positon, but then crossed it at the relay by battery it would bypass all that wiring from keyswitch?... Tom I Told Him to join up on there so we can ask! He has just been working so damn much and then everytime we work on this car we take one step forward two back!, keep finding all this guys lies! grr

Yea that's possible Try Key to the on position, jump the starter relay next to the battery. Start position of key has a higher voltage then run position. Does the car have a dual ballast resistor? White ceramic / 4 terminals?

Yes It does Tom. I also remember my brother telling me the guy said sometimes the car only starts when u let off the key? u think the ignition switch is screwed up?

If the resister has two posts on each side the start side of the resister might be bad. If you run a jumper between the posts (distributor side) of the resister and it starts replace the resister. You can also use a test light to see if you get power to one post with the key ON and the other post with the key at START.

I checked voltage at the ballast on the hot side and in the on pos it has juice, then when u crank it the other side has that same juice , plus we tried two diffferent ballasts too.. what i don't understand is the spark issue when the dist is out.. has blue as the sky but put it back in the block and its gone!... How do i check the car for a good ground or bad ground? Seems to me like its a ground problem? maybe a bad ignition switch?

Most of the time it's the resistor (most mopar guys have a spare in the glove box) Get one and try it. There cheap. I really don't think the dist needs to be grounded. All the ECU looks for is a pulse from the pick-up you get that from the reluctor passing the pick-up plate. try a new resistor. You could also run 12volt to the pos side of the coil and see if it fires up.

Tom We tried two ballasts.. the original and a new one, samething for both . U know as well As I do it was running before just not well with all the other crap we found!. now this..

Try running the wire from the battery to the pos side of the coil. this would eliminate the ignition switch. Also make sure you have good battery(-) to block ground, while cranking to starter may be drawing all the gournd it can.

I thought I read somewhere not to do that to a stock mopar coil as they were designed for 6 volts? How would I check to see if i have a good ground there? Tom If the tach wire isn't hooked up from the coil would it cause this? as the tach has not worked since he got it

You can run it to see if it will start it has close to 12v while cranking anyway then cut back in the run position. Tach should be hooked to the neg side of coil. and won't keep it from starting.

IT's either a pickup coil or a module.IMO.

Mike he said if he takes it out and spins the dist by hand it sparks good??? Only thing I can think of is no or improper voltage at pos side of coil while cranking. I hope he can fix this, it's been a nightmare for him.I have a'72 'Cuda 340 so I know once he gets this fixed he'll be happy with the performance from a good running 340.