Looking for suggestion for troubleshooting an electrical/ignition problem

[gumbyz13]

Looking for some suggestions on an issue I am having.

 

Having a starting problem with my 72 510 (L20B) that has me going in circles.

 

Got the car running but it just shuts off.  Sometimes it will run for a few seconds and then shut off and other times a few minutes.   I originally thought it was an issue with the E12-80 module so swapped that out and still same issue.  

 

Traced it down to my coil not firing.  Hooked up my timing light to the coil wire so I could watch what it was doing.  Everything good while running and then it would just shut off like someone turned off the key.  After it happens it will not re-fire right away and I need to let it sit.  The last time it happened I grabbed a multi meter to check power to the coil and it is still getting a full 12 volts after it shuts off.  Even when it will not start it is still getting voltage to the coil.

 

A few things I have done already with same results

Swapped coils (MSD balster 2 coil and stock coil)

New coil wire

Swapped E12-80 modules (new rotor and cap on distributor)

Verified continuity on all fuses

Checked Grounds (did not find any loose of the ones I could find)

Checked wiring harness for loose connections (Wiring harness is pretty much stock with some of the wires replaced due to being old)   

 

What am I missing, Any thoughts?  Would be nice to have this thing running so I can get it up to JCCS tomorrow.

 

Thanks

[banzai510(hainz)]

matchbox use the MSD or a a 79 coil. if stock coil it will heat up and possibel cook the stock coil unless the ballast resisitor is there in the circut.

 

if you say the key is off and you still get 12volt to the coil then disconnect the volt reg and see if 12volt to the coil or blk wht wire. This really goes thru the key swithc but I heard of cars still running when key off and its usually the old volt reg on the strut tower( I will assume its still a external volt reg and alternator)

Or you mean when it quits running and key still in ON you get 12volts. Then ck the trigger wire. C) is good connection or the relutor inside dizzy.

 

why you guys do this a day before the show?

 

 

maybe its running out of gas cause of a float bowl issue. Pour gas in carb when it shuts off and it starts up again then its fuel issue.

[datzenmike]

  The last time it happened I grabbed a multi meter to check power to the coil and it is still getting a full 12 volts after it shuts off.  Even when it will not start it is still getting voltage to the coil.

 

 

If the above is true and you have power to the coil but no spark when cranking then....

 

Loose power wire to the matchbox. No power to module... no work. Check for 12 volts on the B terminal of the module.

Negative wire from coil to matchbox loose or faulty. This is the C terminal on the module.

Dizzy not grounded properly. Run a separate wire to ground yourself. Don't trust the one there.

[gumbyz13]

Thanks for the info guys.  All power going to the proper places and all connections are solid.  Checked everything numerous times trying to eliminate as much stuff as a potential problem.  Dizzy has a separate ground as well.  Also installed coil and module on friend's car to verify and they worked fine.  

 

Not a fuel delivery problem checked that one too.  

 

My next step is to tickle the undercarriage and see where that gets me...

 

why you guys do this a day before the show?
 

 

 Not by choice...This has been a 4 month build and was just finally at the point where I could get her fired-up.  Had hoped on having her done weeks ago just didn't happen.  At least she looks good sitting still (for now).

[KlassicMotion]

When the car dies and won't start, have you checked for spark from the coil with the timing light as you are cranking it over?

[gumbyz13]

When the car dies and won't start, have you checked for spark from the coil with the timing light as you are cranking it over?

 

Yes, I keep the timing light on the coil wire while its running so I know when it cuts out.  Measure voltage before and after to find difference.  Have not found anything yet.  

[KlassicMotion]

Sorry I miss read that... So you have 12v to the coil, but no spark out the coil wire... How old is your coil wire? How many ohms does it read? And is there a loose connection in the coil wire?

 

 

***posted next day****

 

Man, I didnt' read your original post very well at all, sorry.

[datzenmike]

IF NO SPARK WHEN CRANKING AND YOU HAVE....power to the coil + and also the B module terminal, and the dizzy is well grounded (did you run your own ground? or relying on the one that's there? Nothing must be left to chance here) If these were changed...

 

Swapped coils (MSD balster 2 coil and stock coil).......................... CAN'T BE COIL

New coil wire................................................................................... CAN'T BE COIL WIRE

Swapped E12-80 modules (new rotor and cap on distributor)........ CAN'T BE MODULE

 

The only possible thing left is the reluctor and stator set inside the dizzy.

 

GET A VOLT METER. Motor warmed up and verified not firing after each test. Remember this is an intermittent  problem

 

1/ Measure between battery negative and dizzy case with the coil wire pulled from the cap and grounded. While cranking the voltage must not be more than 0.5 volt. More than this you have a ground problem.

 

2/ Measure resistance between the red and green wires to the module. Should be about 400 ohms. If well above or below, check wire connections.

 

3/ Measure output between RED wire and ground while cranking. Meter needle should fluctuate if working. If not check wire connections.

 

[banzai510(hainz)]

try swapping out the ignition fuse or wiggle the key connector on back of key.

Maybe soemthing is heating up.

 

swap another dizzy in would be my next choice if possible.

your getting power and swapped coils there is nothing left besides a ground. or reluctor inside dizzy

[LB2]

Are you still running a ballast resistor? Because if it's getting red hot it won't run the ignition, but when it cools it will. Ive see this happen before years back. Remove the resistor (if still running it) and make sure your coil is correct for the distributor.

[gumbyz13]

Thanks for the assist guys...Couldn't get the car started so decided to just try swapping the distributor with an old one I had laying around.

 

Fired right up, let her run for about 15 minutes...adjusted timing, balanced carbs, shut her down.  Fired right back up.  Running good right now.

 

That distributor I took out was a rebuilt one I picked up not to long ago with maybe 500 miles on it.  Would not have thought it would have crapped out so soon.

 

Still have a few things to sort but should be driving in a few days.  Looking forward to having it move under its own power again...

 

Thanks for the help.

 

On a side note, had a big ass fire out here this weekend and was evacuated.  Came up quick and we got out as the fire was just about in the back yard.  Fire Department kicked ass on the ground and in the air and saved all the houses.  Down side, my 510 took a nice, red fire retardant shower.  Little rough on the paint but considering the alternative it is fixable.

 

[KlassicMotion]

^^ That wouldn't happen if the car sat inside!!    :poke:   :D   

Of course, had it been inside and the house caught fire.... well then... sad story all around.  Glad no harm came your way!

 

I'm glad you got it running!  Did the distributor come from a specific vendor?

[gumbyz13]

Thanks...as close as the fire was when I was heading out I really thought I would be returning to a pile of rubble.  

 

The distributor was a rebuilt unit I ordered through Autozone (Cardone).  Need to check the warranty info on it.