MSD/Starting/Charging Issue, Novice Needs Help

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SC69DART

SC69DART

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Hey FABO members, you have helped me greatly in the past so here I am again.

The short of it:
A. system not charging, new VR
B. starter cranking like the timing is too far advanced, but it isnt!
C. MSD question regarding 12v to my distributor per diagram supplied by MSD.
It shows switched 12v going to my Mallory Unilite Distributor, the problem is that when you crank it to start the engine the 12v to the distributor is gone, its now in the brown wire (start circuit, old coil wire)....and the car wont start.
When I add the brown wire to the circuit it fires up but the volt meter reads about 10v and the car is running rough.
Something just doesn't seem right.

Can you guys take a look at this diagram of my system and see if you can tell whats wrong. The drawing is showing the brown wire not tied in, as shown, the car will not run. If I take that brown wire (old coil) and tie it to the blue(start) the car will run but its running rough.

Does it look like the VR is wired right?

Any help is greatly appreciated.
Greg


dart1wiring.jpg
 
Wiring looks correct to me. If the system isn't charging and only providing 10 volts it will not crank good and probably won't run right because it doesn't have enough voltage to properly fire the ignition. Have you tested the alternator?
 
I will check the alternator tonight. Do you think connecting the brown (start) wire from the ignition switch to the blue/wt wire (run) from the ignition sounds right though. The image I posted above shows a non-running situation. It just seems weird to have to tie these two together to get it to run.
 
I followed the MSD site diagram specifically for Mallory Unilite Dist. It has a 12v switched source going to it but...it has not mention of the old coil wire. It did say that no other wires except the 2 (orange and black) wires from the MSD box should be on the coil.

Alternator: There is a small green wire from field, a thicker blue wire from the other field and a heavy black wire to battery. I hooked the two field wires to the VR and per diagrams I found online, also tied in the 12v switched ignition to one of the fields.

Just some more information to ponder. That old coil wire troubles me.
 
Unless there is something IN THE CAR mis wired, or something wrong in your ign switch, the brown should be "dead" in run, so you should be able to tie together the brown/ blue to solve the start issue.

HERE IS WHY. Originally, many Mopars "kill" the blue line when you twist the key to start, and the power is replaced by the brown IN START ONLY. This brown went directly to the coil, so you got a nice hot spark, but when you RELEASE the key to run, the brown goes dead, the blue becomes hot, and the blue then feeds power THROUGH the ballast resistor to run the system.

You MAY be having a serious voltage drop issue IN THE CAR WIRING.

Turn the key to run, engine off, and measure the dark blue at some point, such as alternator field. You can measure voltage drop DIRECTLY by putting one probe directly on the battery positive, the other on the blue field connection. You should show LESS than 1/2 volt, and 1/2 volt is generous. MORE indicates a drop in the harness path ---from battery--fuse link--through bulkhead--ammeter circuit--to ignition switch connector--through switch and back out connector--back out bulkhead--to dark blue such as field.

No1 suspect is the bulkhead connector.
 
SC69DART said:
I will check the alternator tonight. Do you think connecting the brown (start) wire from the ignition switch to the blue/wt wire (run) from the ignition sounds right though. The image I posted above shows a non-running situation. It just seems weird to have to tie these two together to get it to run.
Click to expand...

No you do not want the brown wire tied in with the blue/white wire. It does not show that on the diagram you posted above. Where did you get the idea you'd want to do that?
 
SC69DART said:
I followed the MSD site diagram specifically for Mallory Unilite Dist. It has a 12v switched source going to it but...it has not mention of the old coil wire. It did say that no other wires except the 2 (orange and black) wires from the MSD box should be on the coil.

Alternator: There is a small green wire from field, a thicker blue wire from the other field and a heavy black wire to battery. I hooked the two field wires to the VR and per diagrams I found online, also tied in the 12v switched ignition to one of the fields.

Just some more information to ponder. That old coil wire troubles me.
Click to expand...

I run a Unilite with a MSD box and it is wired exactly as above and does not use the brown wire.

67Dart273's description of why not to use the brown wire is spot on.
 
10 volts? That battery is beyond dead.

If you have a battery charger, put it on the battery overnight. Trying to charge a battery that badly drained once you get the charging system working can be very hard on an alternator.

The charging system problem is fairly easy to troubleshoot. One field wire is connected to +12v with the key on. The other field wire goes straight to the regulator.

Disconnect the wire that runs straight to the regulator from the alternator. This should leave you with +12v on the still connected field wire with the key on. Now check the voltage at the other field terminal, it should be close to the voltage at the other field terminal. If it is zero volts, then your alternator has a bad brush or rotor winding.

If you have voltage on the field terminal that you disconnected the regulator from, start the car. Connect your voltmeter to the battery. Connect a jumper wire to the field terminal on the alternator that you disconnected the wire from. Ground this wire while observing the battery voltage. If the alternator is ok, it will charge at it's maximum output. This is "full fielding" the alternator. You may see charge voltages as high as 17v. This test should be done only long enough to verify alternator output.

If the alternator charges when full fielded, then the problem is the regulator, or a wiring defect.

Hope this helps.

B.
 
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