Needs a diode maybe?
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Fleet Mechanic
Joined: Jun 2019
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From: Southern California
Needs a diode maybe?
I just finished installing a fresh 390 FE motor in a customer's 65 Galaxie 500. Sorry, no pics, my phone is broken. I put a Summit distributor and coil that needs 12V to the coil. I wired up a relay using the original B+ to coil to trip it, but, it will not turn off with the key. I figure something is back feeding. Should I dut a diode inline before the relay? Or what am I missing? Thanks, TK65
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Do you have the relay contacts connected properly so you don't have hot at all times voltage running to the coil? IOW does the +12 VDC come and go with the relay being switched on?
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Fleet Mechanic
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From: Southern California
The only thing hooked to the + side of coil is my power wire from relay, and the red wire from distributor. Coil - has orange wire from dizzy. It's a three wire unit, the third goes to ground.
At the relay, I have my B+ coming from thebattery cable stud on the start relay, B- to valve cover bolt, switched power from the ignition + that used to go to coil. (resister wire?) and of course the 4th wire goes to the coil.
Thanks for looking
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Unplug the connector to the alternator regulator. Then try it and see if the problem goes away. Of course the alternator will not charge, but this is just a test. If the problem goes away, the alternator system is backfeeding up the ignition side of the circuit. A diode in that circuit may help if that turns out to be the problem.
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Fleet Mechanic
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From: Southern California
Unplug the connector to the alternator regulator. Then try it and see if the problem goes away. Of course the alternator will not charge, but this is just a test. If the problem goes away, the alternator system is backfeeding up the ignition side of the circuit. A diode in that circuit may help if that turns out to be the problem.
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From: Virginia
A diode may fix it. You need to find the green/red wire that goes to the "I" terminal of the regulator. Come back from the plug a little bit and cut that wire. Then plug the regulator back in and test it again, just to make sure we are on the right track. Your problem should still be gone, but it still will not charge, even though the regulator plug is back in place. That green/red goes to the ignition switch and brings the alternator online to charge when the key is turned to run.
Once you get your diode, it should have a band on one end. Put the band toward the regulator. Hook the other end to the wire hanging in the harness, hopefully your problem is still gone and double check that the alternator is charging. You should have something higher than 12v when it's running. A old car like that probably has around 13.5v or so when charging.
Once you get your diode, it should have a band on one end. Put the band toward the regulator. Hook the other end to the wire hanging in the harness, hopefully your problem is still gone and double check that the alternator is charging. You should have something higher than 12v when it's running. A old car like that probably has around 13.5v or so when charging.
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Fleet Mechanic
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From: Southern California
Okay Dave. I called my electrical rebuilder to get a Porsche alternator ordered and asked if he had any diodes, he of course asked why. When I told him he basically repeated what you said in your last post. He sent me a couple diodes with the alt, I soldered it inline and the Galaxie starts and turns off with the key, and charges! Took it for a drive and the new 390 I just put runs great! Thanks for walking me through this, much appreciated.
Dan
Dan
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