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Discussion Starter #1
Hello Everyone!

I have been fighting my mustang for awhile it has a 89 5.0 in it, I'm running a carb with a gm hei ignition mod. I have had the car run for about a hour, and I went to shut it off and to my surprise it wouldn,t shut off. The key was in the off postion and it kept running so I pulled the coil, and the positive battery cable. When I put the positive battery cable on the ignition will start up, and anything wired to run in the ignition on spot.

I replaced the ignition switch, it did't solve anything. Now I thought you dirty old solenoid, so I replaced it bingo every things fine. I drive for about an hour again and go to shut it off, and same problem. So is it just a crappy new solenoid? or is there something deeper here that causing them to fail? If i pull the (I) wire on the solenoid nothing runs with the battery cable on.
 

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How is the distributor/coil wired? Do you have them connected to the I position of the starter relay (most likely what you called the solenoid)? There should only be one wire connected to the I position (262 - brown). The coil/distributor should be connected to the ignition switch via wire 16/16B which is red with green stripe. This wire and the wire to the I position of the relay (262-brown) are connected to the pink wire (16 A) with the resistor. This connection point "D" appears to be at the firewall. The pink wire is connected directly to the the C position of the iginition switch.

Could you post a picture of your starter relay?

You mentioned the car functioned properly when you replaced the relay. Did it start and shut off correctly with the iginition switch?

Sounds like you have some type of short at the relay that is causing the the iginition circuit to stay energized after the ignition switch is in the off position. It seems to be back feeding the circuit and running back to the coil.

I don't know if Veronica is keeping an eye out but she is the wiring diagram guru and may be able to offer some advice. I know the '68 wiring diagrams show a pink resistor wire connected to the "I" circuit like my '65, but I'm not sure what happens if this wire goes bad or is connected properly.
 

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Discussion Starter #3
The ignition switch on, runs to the coil from the main harness, then it runs from the + side of the coil to a 4 point gm HEI, then from there to the duraspark distributor. The only wire on my (I) terminal of the solenoid is the brown wire, the (S) terminal is a red and green wire. The positive side of the solenoid closest to the battery has some wires that run to relays that power the electric fans, relayed lights,and what ever was there stock, the farthest solenoid terminal(away from battery) has the cable that runs to the starter.

I just wonder how I can have two solenoids that leak voltage when the ignitions off, to the (I) terminal?
 

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Sounds like it is connected correctly. Try this: Turn the ignition switch to on position. Then measure your voltage to ground at the I position of the relay and then from the coil + to ground. Hopefully (most likely) you'll have 12 volts at both. Then turn the switch to off and measure voltage at the locations hopefully 0 volts. Then disconnect the starter lead from the relay (just so the car won't start). Then measure the voltage of the starter lead (big terminal) to ground with someone holding the ignition switch in the start position. Measure the voltage at the I terminal and the coil to see if you have 12 volts at each. You'll probably have a little more than 12 volts at the starter lead. If all this checks out it would seem it is connected correctly. Then turn the switch back to just Ignition on and check it all again, then back to off. This is where you may see the 12 volts staying on with the key off.

If it all works out, follow the "I" wire and coil wire back to the firewall and up to the ignition switch. Look for any cracks in the wires on the firewall side that would allow for a short from the battery lead to the ignition switch over to the I or coil wires. Sounds like something is heating up over time and then touching to create the short.

BTW the starter relays are made in China and for all intents and purposes they are junk. It would not surprise me to have two fauty ones.

Good luck and post your results.
 

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I forgot to ask: what type of HEI are you running and how is it connected. I looked at a Mallory type and it shows a battery feed to the starter relay positive side as well as connections to the iginition wire from the switch and coil. You may have a problem within the HEI module since it has both iginition and constant hot battery feed.
 

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Discussion Starter #6
Thanks for your reply,
I'm running the poor mans HEI which is just a gm 4 pin inside a durspark box, and my coil is a msd TFI. I will have a look at my wiring tomorrow. Now I'm wondering can the 4 post solenoid have accesories ran off the front terminal or is this too hard on it and I need to run a seperate wire from the ignition switch?
 
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