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Old 05-05-2013, 02:55 PM
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Default Can't turn off engine after HEI upgrade

Looking for some guidence here.

89 Whanger 4.2. Motorcraft 2100 with an HEI upgrade.

After snooping around some post, decided I needed a relay in line with the power to the distributor....not enough amprage in the exting wire.

Well, after two different relays, I cannot turn off the engine with the key.

I picked up a 40A relay 4 prong. With the engine off, 1 wire has 12 v (fused link from battery. The other three have no voltage.

Start the engine, fires right up. Three wires have 12v power. Turn the key off and the motor stays running. Three wires still have 12v. I have to unplug the dist wire to get it to turn off then the three go back to no voltage.

I am running my switched power from the starter solenoid. WTH is going on.

Any advise would be great. Thanks
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Old 05-05-2013, 06:02 PM
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So you're drawing power from the un-switched side of the solenoid through a fuse. That's fine. Another wire runs to the distributor supplying it with power. What are the other two connected to?

In concept it's a very simple circuit - from the ON side of the ignition switch to one side of the relay coil, and the other side of the coil to ground. Then your power source, somewhere close to the battery, to a normally open contact on the relay, and from the other side of the NO contact to the ignition system.

There's a wire from the ON side of the ignition switch to the alternator that supplies a little power to the alternator which it needs to bootstrap itself into operation. Once the alternator is producing power that wire is hot, and it stays hot as long as the alternator is spinning. That can feed back to the ignition switch and from there to your relay, keeping it engaged.

If that's what's happening the easy cure is to put a diode in the excite line to the alternator so that current can flow to the alternator, but not back to the ignition switch. And the way to test the theory is to start the engine, turn off the ignition, and then unplug the small connector from the alternator. If that kills the engine you've found your problem.
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Old 05-06-2013, 11:44 PM
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Is this a new HEI swap or did it work fine and then just start happening?

I'm thinking it should be on a 20 amp fused key on circuit or possibly a inline fusible link. Factory it appears there's no fuse in the ignition circuit but a fusible link. I don't believe most factory HEI setups had relays. GM didn't really start using relays till they went to fuel injection.

Are you attempting to get rid of the computer controlled carb/ ignition disaster and upgrade? If so read on, if it was working fine and just "happened" then Jim Lou's advice is probably it. Here's a wiring diagram, there is a resistor inline from the alternator to the ignition module, it "should" be yellow with a brown wire going to the alternator with an inline resistor (the alternator/ battery light might be the resistor). | Repair Guides | Wiring Diagrams | Wiring Diagrams | AutoZone.com

Do you have an HEI distributor with the coil on the cap? It should only have 2 wires going to the cap, a 12 volt key on hot and a tach signal. You will have 3 wires going from the coil to the distributor. You want to focus on the wires from the engine wiring harness to the coil, not the coil to the distributor. If you have an HEI system that doesn't have a coil on the cap, what's the donor application so I can find the right wiring diagram. Did you check and see if the bat wire is hot all the time even with the key off? I'm wondering if you maybe wired it to an always hot terminal on the starter relay or solenoid.

These are "generaic" HEI swap distributor instructions but they should help http://www.4wd.com/Instructions/PD/DUI_Install.pdf

I looked at a wiring diagram and it made my head hurt but here's where I would start looking. There's a green and a yellow wire coming out of the ignition switch, originally the yellow went to the ignition module, coil, and t-ed into a brown wire that goes to the alternator. Unplug the distributor/ ignition coil (to eliminate a distributor problem), at the distributor check to see that when the key is off it's cold, turn the key to the crank position and also the key on positions, it should be hot. If that's the case hook that wire up to the bat terminal and see if your problem is solved.

If you still have the computer/ most of the wiring for the emissions disaster you can really simplify it with HEI and a MC 2100 and loose a ton of wire. You should only need a bat wire to the distributor that's hot in the start and run positions, Tach signal wire from the tach terminal on the distributor/ coil to the tach, oil and temp sender signal wires from the sensors to the gauges, electric choke wire that I believe should be hot in the run position, a wire to the starter relay and then to the solenoid that's hot in the start position, and a wire to the alternator that's t-ed into the distributor bat wire with a resistor (on a GM the resistor is an indicator light, the wires going in/ out of the light are hot in the run position but the light grounds through the alternator and only grounds when the alternator isn't working, I don't know if that's how the jeeps are set up of if there's an actual inline resistor) . Hopefully the auto zone wiring diagram will help that make sense.

I'm by no means an expert but that should start you in the right direction. The pre 4.0 carbed YJ's have a mess of wiring under the hood that can be scary till you realize how much of it you really don't need.
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Old 05-20-2013, 06:03 PM
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I think you need a diode in the switched circuit to the alternator. It can be installed near the alternator so you don't have to dig through any wiring harnesses.

That was the problem I had with my 88 not turning off when I installed an MSD ignition.
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Old 05-28-2013, 10:10 PM
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Quote:
Originally Posted by yamamoto View Post
Looking for some guidence here.

89 Whanger 4.2. Motorcraft 2100 with an HEI upgrade.

After snooping around some post, decided I needed a relay in line with the power to the distributor....not enough amprage in the exting wire.

Well, after two different relays, I cannot turn off the engine with the key.

I picked up a 40A relay 4 prong. With the engine off, 1 wire has 12 v (fused link from battery. The other three have no voltage.

Start the engine, fires right up. Three wires have 12v power. Turn the key off and the motor stays running. Three wires still have 12v. I have to unplug the dist wire to get it to turn off then the three go back to no voltage.

I am running my switched power from the starter solenoid. WTH is going on.

Any advise would be great. Thanks
Thing is you don't need a relay. The simple answer is that you need a connection to the main switched voltage source.... HEI will run very happy off the 12V provided by the ignition switch....

I can't tell you exactly where because 1989 is just a bit too new!!!

Funny how the same topics repeat... Rinse, Later, Repeat...

Don't even tell me that you have 00 gauge wire running it.


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Old 05-28-2013, 11:01 PM
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Holly Smokes old thread.....

It was September of 2008 that I went with an HEI ignition in the Red Jeep... While it may need a bit of work now... It's the first time that it has needed any work.

Click on this and read... http://forums.off-road.com/jeep-shor...stributor.html (4WD HEI Billet Distributor)

Strange that all of those "Experts" removed their posts, deleted their comments and moved on.

That is the type of BS that made me move on.... Why argue with someone that isn't armed for the discussion.

BTW: My old Scrambler... Still runs a "Stealth HEI" and while it is not driven more than a couple of times per month... It fires up an runs well:

I think that I can still search here and find things... That is good since my memory sucks. There are other fun threads (likely missing many posts (deleted by butt monkeys on a rant)) related to this very topic.

Yes that includes how to run your ignition on a relay.


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