70 Cuda no spark, I think

[usraptor]

Okay, '70 Cuda 440 with 512 Stroker, Aluminum heads, Holley dominator intake and Quick Fuel 880 CFM SS carb.  During the restoration and engine rebuild I converted the ignition to an electronic ignition using the Summit Racing® Electronic Mopar Distributors SUM-851005 kit.  Since then I've had nothing but problems with an intermittent start issue.  I thought I had it resolved as last summer I didn't have any problems getting the engine to fire.  Timing is set to 36 degrees at full advance.  Put it away for the winter on a battery tender and have tried to start the engine on a few occasions.  The first time the engine just spun.  Acted like a no spark condition.  I thought I had possibly flooded it and let it sit a few weeks and then it started right up.  Went out the next day and it just spun again like it had no spark.  Unplugged and replugged in the ECM connection and it fired right up and started up several times that day with no more issues and engine ran smooth.  Just went out and tried to start it to move it to the lift and it just spins again, doesn't even try to start.  Unplugged the ECM and replugged it and it still just spins.  Turned the key on and put a voltmeter on both sides of the coil and I have 12 volts.  I put my in line spark tester on the no 1 plug and since I'm by myself I used a remote start set up hooked to the battery and starter switch on the driver's fender.  With the key in the run position and turning the engine over with the remote start button  I'm not getting any spark according to the in line spark tester.  FYI, I have good grounds as I've removed paint to bare metal on the radiator support where the small negative wire attaches as well as have a good connection on the large ground wire to the aluminum head.  I also ran a small ground strap from the back of the intake manifold to the ECM bolt where it connects to the firewall, also to bare metal on the firewall as well as the engine.  As I've said several times before I'm not the sharpest knife in the drawer when it comes to electronics;  so I'm not positive that if I'm using the remote spark with the key in the run position am I supposed to get a spark when I don't have the clutch depressed?  I thought the clutch safety switch was just that, a safety switch to make sure you didn't try and start the car in gear and therefore using the remote start switch I should still have spark with the ignition turned on, correct?   If this is correct, any suggestions on why I have 12 volts on both sides of the coil and no spark to the plugs?  I'm just about ready to put the OEM distributor back in with a point ignition.   

[JS29]

I would try your in line spark tester on the coil and coil wire and thy that. I do not believe the clutch switch has anything to do with spark. its per pis is that the starter won't engage. 

[JonH]

As JS said safety switch only affects starter not ignition. Do you have another ecm? If so change it out, to a known good one. If not that it would most likely be the module in the distributor. If you are sure of your grounds, my guess is the ecm. All the new stuff is crap...

[usraptor]

Thanks, after I wrote this,  I went back out, tried everything again and this time got a weak spark showing on the in line spark detector.  Sprayed some starter fluid into the carb and it fired right up.  So I'm at a loss as to what's going on.  Any suggestions on what would cause a weak spark other than a ground issue?  This is so frustrating as I had no problems this past summer getting it to fire right up.  I let it sit for a couple of months and now I have issues and nothing has changed. since I parked it.

[dodj]

The first thing that came to my mind was a poor connection in the wiring. I would remove the bulkhead connectors and make sure the start and run connections there are good and clean and tight (the brown and blue wires). As JonH alluded to, I've heard the new Mopar style replacement ECU's are not of the most consistent build quality - Also a possibility. Have any friends with a 4 pin mopar ecu to try?
Are you sure you are getting fuel when you try to start? How about before you try to start, look down the carb and flick the throttle a bit. Ensure there is fuel getting squirted in.

[Brads70]

    gets rid of the ballast resistor as well! 

[usraptor]

The first thing that came to my mind was a poor connection in the wiring. I would remove the bulkhead connectors and make sure the start and run connections there are good and clean and tight (the brown and blue wires). As JonH alluded to, I've heard the new Mopar style replacement ECU's are not of the most consistent build quality - Also a possibility. Have any friends with a 4 pin mopar ecu to try?
Are you sure you are getting fuel when you try to start? How about before you try to start, look down the carb and flick the throttle a bit. Ensure there is fuel getting squirted in.

Dodj  Yes, fuel sights in the bowls show fuel and I did work the linkage and got a good spray of gas.  I'm getting ready to pull the engine and have my engine builder swap the current stroker guts, etc over to a non numbers matching block so I can rebuild the numbers matching block to stock and leave on an engine stand.  I should have done this to start with but.....  Anyway, while I've got the engine out I'm going to go through and check my wire connections again, both at the bulkhead and where I spliced the ECM wire into the wire harness as a bad connection also came to my mind.   Thanks for all the suggestions, I'll report back when I get the engine out and check the connections.  It will be much easier to do so with the engine out then with it in.

[Racer57]

Assuming you have a tach, try disconnecting it. I had one that was shorting out intermittently. 

[dodj]

   gets rid of the ballast resistor as well! 

While I agree with you opinion there Brad, he already has the single resistor, which means initial startup is without the resistor. So as far as the engine catching and trying to start, it is not the issue........this time.

Assuming you have a tach, try disconnecting it. I had one that was shorting out intermittently. 

YES!! Forgot about that. The stock tach killing the ignition is too common an occurrence to ignore.

[usraptor]

Assuming you have a tach, try disconnecting it. I had one that was shorting out intermittently.

Racer57, I had the issue before last summer and after changing the tach connection from the factory bayonet style to a insulated ring style wire connection the issue was resolved.  Have no idea why this made a difference but it did.  Also, I just changed/upgraded my tach with an RTE circuit board.  So the tach was the first thing that came to mind.  I disconnected it at the coil and it didn't make any difference.  Yesterday when I got the engine to fire with the starter fluid I touched the tach wire to the coil while the engine was running and it did not kill the engine so I don't think the tach, especially with the new circuit board, is the issue but thanks for the suggestion.

[HP_Cuda]

Swap out the ECM, it seems to be giving you the intermittent problem.

Heck even a stock setup should work well.