MSD issue

-
72ScampTramp

72ScampTramp

Scamp Tramp
Joined
Jan 13, 2009
Messages
4,406
Reaction score
172
Location
Fort Dodge Iowa
So I took the scamp out to warm up to flush radiator. Seemed to run ok. Pulled into the drive shut it off to cool to drain. No fire when i went to start. I checked for spark using the coil wire. I got spark when flipped to the on position but no spark in run. I have a street fire box and is connected the 2 wires together from the old ballast that connection is good. Where else could my issue be? Guess im not even sure where that power comes from. Fuse or breaker of some kind?
 
if you are using a mopar electronic distributor...

check the pickup coil air gap....or the pick up coil is bad..
 
72ScampTramp said:
I got spark when flipped to the on position but no spark in run. I have a street fire box and is connected the 2 wires together from the old ballast that connection is good. ... Guess im not even sure where that power comes from. Fuse or breaker of some kind?
Click to expand...
The ignition gets power in the "run" key position from the IGN1 wire (usually blue). If the "on position" means "ACC", you shouldn't have ignition power then. Indeed, that wire doesn't even go to the engine bay in my cars (you didn't state your year, 1972?). In the key "start" position, the IGN2 wire gets power (thick brown), and not IGN1, but since you jumpered your ballast connectors together they are the same. Your problem could be in the key switch, wiring, or bulkhead connector. My guess is the key, since the only place ACC and IGN1/2 come together. Without a multimeter, you will probably never resolve it.
 
72ScampTramp said:
So I took the scamp out to warm up to flush radiator. Seemed to run ok. Pulled into the drive shut it off to cool to drain. No fire when i went to start. I checked for spark using the coil wire. I got spark when flipped to the on position but no spark in run. I have a street fire box and is connected the 2 wires together from the old ballast that connection is good. Where else could my issue be? Guess im not even sure where that power comes from. Fuse or breaker of some kind?
Click to expand...


if you have the old ballast resistor wire connected together..then the msd is getting both run and start voltage unless one of those wire is having problems from the ignition switch..or firewall bulkhead...

check the voltage if you can of those two wires before they are jointed...one at start..one at run...

but you might getting one or the other back feeding the other...

another simple thing...use a jumper wire from the battery straight to the msd switch wire....the one coming from the ballast resistor to see if it is not the box or it is wiring...
 
70aarcuda said:
if you have the old ballast resistor wire connected together..then the msd is getting both run and start voltage unless one of those wire is having problems from the ignition switch..or firewall bulkhead...

check the voltage if you can of those two wires before they are jointed...one at start..one at run...

but you might getting one or the other back feeding the other...

another simple thing...use a jumper wire from the battery straight to the msd switch wire....the one coming from the ballast resistor to see if it is not the box or it is wiring...
Click to expand...


Well I went out today and did this. And it fired. So what ever my issue is has to be from that connection or bulk head or IGN switch.
 
Ive chanced nothing electrical any time recent. The car has run since then. My electrical isnt very strong but here is what i found

The 2 wires blue and brown from the original system I get

Blue-0v in start position and 11v in run position

Brown-9.5 in start position and 0v in run positon

I did have the fuel pump running dead head off them which may explain some drop.
 
Both of those are low. You've prob'ly seen some of my preachin' LOL about voltage drop

Top suspects are the bulkhead connector for the battery infeed and charging line, the two feeding out the blue and brown, and then the connector and ignition switch itself.

More rare, but "does happen" are problem connections at the ammeter, and a failed "in harness" splice.
 
67Dart273 said:
Both of those are low. You've prob'ly seen some of my preachin' LOL about voltage drop

Top suspects are the bulkhead connector for the battery infeed and charging line, the two feeding out the blue and brown, and then the connector and ignition switch itself.

More rare, but "does happen" are problem connections at the ammeter, and a failed "in harness" splice.
Click to expand...


Both are low yes.... But the scope of thing is the MSD box already has a 12v batt supply... This would be basically a switch telling the box the ignition is on. Given it worked like this before I suppose its possible its a problem now.


I also noticed an weird occurance. When i was testing wires under the column. I noticed when i had my meter hooked up on it would not even crank over. But once i removed the lead from the it would crank over like normal?
 
Whats the best way to make connections? See i have those 2 wires the brown and blue.. They supply power to distributor, fans, fuel pump and MSD box. Whats the best way to make multiple connections to those wires? Would there be a multi port terminal i can make or buy? Why im doing this id like to clean up the wiring.
 
72ScampTramp said:
They supply power to distributor, fans, fuel pump and MSD box. .
Click to expand...


My mind skipped for a second that the MSD wire is just a relay driver at this point.

But are you trying to drive pumps, fans DIRECTLY, or is this wire just firing relays?

What are you running for a charging system? this point electrically also normally supplies regulator / alternator field. Having voltage drop problems at this point will cause overcharge (overvoltage)

Now knowing "how" you did this, solder and heat shrink, terminal strips, several ways to approach
 
67Dart273 said:
My mind skipped for a second that the MSD wire is just a relay driver at this point.

But are you trying to drive pumps, fans DIRECTLY, or is this wire just firing relays?

What are you running for a charging system? this point electrically also normally supplies regulator / alternator field. Having voltage drop problems at this point will cause overcharge (overvoltage)

Now knowing "how" you did this, solder and heat shrink, terminal strips, several ways to approach
Click to expand...


Fans are relay controlled, fuel pump is not. There ya go a terminal strip. Before i just had them soldered and heat shrinked.

Here is what i did. Originally there were 4 wires 2 blue and 2 brown. 2 are supplying power to my box, fans, fuel pump and dizzy... the other 2 wires are capped off. as far as the alternator i have it wired in with stock harness going to the bulk head.... Did I do something wrong here?
 
Well here is what I have done. Ive went through and cleaned up the wiring. Made junctions and connections to rule. that. out. I have voltage at the 12v keyed source. Jumper wire from battery to MSD box it fires. Wont with out. thinking of running that keyed hot blue and brown directly from the column bypassing the bulk head to see what i get. Good idea or no?
 
Stuff like this makes me glad the bulk head connector is gone on our car....
 
72ScampTramp said:
Well here is what I have done. Ive went through and cleaned up the wiring. Made junctions and connections to rule. that. out. I have voltage at the 12v keyed source. Jumper wire from battery to MSD box it fires. Wont with out. thinking of running that keyed hot blue and brown directly from the column bypassing the bulk head to see what i get. Good idea or no?
Click to expand...
This is what I did before changing all my wiring to the Ron Francis box and harness.I pulled the main power feed from both sides of the junction box(at firewall).I drilled through both and fed a thicker gauge power wire direct with an inline fuse.Depending on the condition of your wires,this maybe just a temporary fix,as you might run into issues with other old,worn,spliced wires.Good luck Josh,don,t ya just love wiring gremlins.:D
 
This puts in perspective. The old would be the last picture. I removed junctions and connections I felt could be better. The 12v wires run into that box and out to the msd box. All connections are soldered and heat shrink so i know those are good. Also ran new coil wire leads as mine were sort of melted. I believe i have ruled out everything forward of the firewall.
 

Attachments

  • wiring loom3.jpg
    54.3 KB · Views: 211
  • wiring loom4.jpg
    64.5 KB · Views: 207
  • wiring loom.jpg
    95.8 KB · Views: 212
  • wiring loom2.jpg
    77.5 KB · Views: 211
Ok after talking with several people last few months. I changed the ignition switch. No start now. While I was having this problem before with no power in the run. I was always able to run a jumper from the solenoid to my MSD connection and it would start. Now I have no fire at all. I know ive got fuel. I know the box is getting a signal as I see the red light come on when i flip the key to on position.
 
Well I went back out. Pulled the coil wire to the distributor and no spark. I had a new coil put it in same thing. Nothing under the dash would be an issue right now... Ive got a Mallory Unilite distributor, MSD coil and MSD Street fire box. Im almost wondering if the module in the distributor took a crap again.
 
Ok I did some testing and I believe the module in the unilite is bad. This is the 2nd one. Anyone else run this distributor? Says with a CDI box a ballast isnt needed. Would one of those power filters help keep these modules lasting longer?
 
FIXED! She runs... Problem was the module in the unilite was bad. I changed out the ignition switch due to a issue having last year. I almost wonder if the module was going bad and supplying the extra voltage made it last just a bit longer. I also invested in a power filter to help protect the new module
 
You must log in or register to reply here.
-

Back
Top