Ignition Circuit Problem, Need Help

[MachOneMan]

I have a 69 Mach 1, 351W Mallory Unilite distributor, MSD Blaster 2 coil. The problem I have is that I'm loosing spark in the cranking mode. I have spark when the key is turned on loose ignition during cranking & then the engine attempts to fire when key is released. I have replaced the ignition switch, coil, regulator but not the solenoid. There is power to the coil with ignition on, power from coil. I seem to remember hearing of this problem before & it was a simple fix that had to do with a wire from the starter, alternator or ? Any help would be greatly appreciated before it goes for a ride on a flatbed!

 

[BarnStang]

Looking at the 69 diagram, the circuit is about the same as earlier years. I haven't looked at the uniite wiring, so some of this may be non-applicable. THe stock wiring has a brown wire coming off the "I" terminal of the starter solinoid. THis provides a full 12v to the coil in start pos. Are you using the red wgrn strip wire on the POS term of the coil? Like I said, not sure you you have the Mallery dist and MSD coild configured...

 

[MachOneMan]

I'm using the Red/Green stripe wire to the positive side of coil along with the Red wire from the distributor. The negative side of the coil has the green wire from distributor. The brown wire from the DISTRIBUTOR is grounded on the block. There is no wire from the solenoid going to the coil unless it is through the harness. Like I said, the vehicle started a few months ago, battery went dead so I charged it & now the problem. Hope this helps explain the Unilite wiring.

 

[mustangman1974]

you somehow bypassed the 12 volt ignition source from the solenoid. when your cranking you should get voltage from the I terminal on the solenoid. Through the wiring harness just at the connector engine firewall side that wire mates with the stock ignition wire. You need to check to see if you get voltage at the coil when cranking. just disconnect the red/green wire and check for voltage while cranking. If you got voltage there you need to check your unilite module. I know with my MBI I have to disconnect it when charging or welding. Its possible you fried it.

 

[BarnStang]

Exactly, so, is there a brown wire coming off the "I" terminal of the solinoid ging into the stock wiring harness? It may be hanging loose. If it's connected, check as mustangman1974 said, if you have no 12v at the coil + when cranking, then that brown wire must be cut or boken somewhere.

 

[MachOneMan]

Barnstang & mustangman74 thanks for all your guidance. The brown wire does come off the I terminal of the solenoid & feed into factory harness. I checked connections & all is good. I have 6 volts at the power to coil wire in the "on " position. It seems that all things are pointing to the Unilite module. I ordered one from Advance Auto parts yesterday & they just called & said it is in. I'm off to drop another $100! BarnStang, what did you mean about configuring the coil?

 

[BarnStang]

Just that I was not sure how you had the coil and dist wired up. There are a lot of different ways to do it-and I'm not familure with the Mallery. Um, wait a sec, you posted that you have the red/grn stripe wire on the pos tem of the coil WITH the red wire from the Mallery dist...ok, pulled the Mallery inst up for Ford conversion, you have it right. Some of the elec ign conv kits will not let you tie the module power wire to the coil with the OEM resistance wire. But Mallery does. You should have a full 12V at the coil n the START pos of the switch. THat's the test we are looking for given your symptoms. WHen you turnthe switch to START, the solinoid closes contacts AND sends 12v out the I terminal. THis feed 12v to the Red/grn stripe wire AFTER the resistance wire ends-giving the coil a solid 12v in START, then when you release the key to run after it starts, the coild get 6-8 volts via the ign switch feeding the pink resistance wire, feeding the red/green stripe wire. So, the question is, are you getting the 12v from th I term to the coil POS term with the key in the Start pos. Check this before yourip the new module out of the pkg...

 

[bnickel]

i had this problem before and it was due to the fact that i had wired in an external resistor not realizing that the factory ignition system already had a resistance wire (the pink wire coming off the ignition switch) so i was basiacally resisting the voltage too much