Engine fails to shutoff

Forgive me, but I'm re-posting this here.

So I had an issue where every so often my 74 CJ5 would fail to shut off. Ran into some issues and ended up replacing the ignition switch, coil, and going to a solid state distributor. Then the issue seemed to take over and I was no longer able to shut it off at the ignition switch. After wiping a main bearing, I replaced the engine and went ahead and rewired it with a painless wiring harness. Had the issue again where the jeep would not shut off. I looked at the painless manual and after reading some I installed a wire from the "I" post of the starter to the Positive post on the coil. (using the Prestolite BID config section 8.2.4 since it most resembled my set up.) Seemed to solve the issue. Ended up needing to replace the radiator so the Jeep sat a couple more weeks and I finished some of the other wiring on the dash and replaced the radiator and went to fire it up. Damn thing won't shut off again. Disconnected the wire I installed between the starter and coil and still nothing. I've been trying to figure this out for days now and am about at the end of my knowledge base. Any help would be great.

Link to the Painless Manual for you to gaze at.
http://www.painlessperformance.com/Manuals/90532Manual.pdf

 

What type of alternator do you have? I have seen several instances where there is not enough resistance in the ignition feed circuit to the alternator and it will backfeed the ignition when you turn the switch off. This happens alot on older jeeps when you change from a generator to a Delco alternator if you run a wire from the ignition switch straight to the alt. with no warning light in the circuit.

 

+1 on the alternator wiring. You may need to put a diode inline to stop the feedback up the exciter wire. I had this problem when I rewired my CJ. The Diode fixed the problem.

 

x2 on the diode

 

Appears to be a Motorola Alternator P/N 8AL2029F? Label is so badly worn couldn't really tell, but I made out the Motorola "M". I'll take some pics and dl them so you can see.

 

The way I understand it is that you have a Motorola charging system but you are not connecting up the way Painless instructions say. Painless sez to use 8.1.3. You say 8.2.4? Do you have an extra starting relay mounted on the fender as well as the solenoid on the starter? For test purposes, I would temporarily unplug the Motorola voltage regulator and start the motor. Turn it back off, and if it shuts down start it several more times to make sure its working good. If the engine shuts down which I suspect it will, we have other issues. Let us know. Tnx.

 

No disrepect Walt. 8.1.3 is the charging circuit. 8.2.4 is the ignition circuit. He can have it wired that way and be correct. Its all about where the power comes from to power the ignition. And where it comes from to excite the alternator. You may have a Motorola charging system, but it works just like the Delco. If you take a look at section 8.2.2 it explains the diode the other guys are refering to. I agree, Your charging system excitor circuit is back-feeding the ignition.
I am running the same Painless wire harness, with Motorola Charging system (8.2.1 and a Delco ignition 8.1.4 and it works great.
I agree with Walt, disconnect the alternator excitor wire and start and stop the engine. If it works, you need the diode.

 

Walt its just the solenoid mounted on the fender. No extra one. Gonna try the test after work today.

 

defenitaly a feed back issue, had the same thing happen to a chevy pickup, wouldnt shut off, but only in reverse, come to find out i had a bad ground to the bed harness, cleaned up the ground and it went away, good luck, hope you just need the diode, finding a backfeed can be a real pita sometimes

 

how exactly do you install the diode? do you crimp it in or solder it in?

 

If you solder it in you have to use a heat sink on the lead being soldered. Diodes dont like heat (high heat) and will be ruined. Did the engine shut down OK when you unplugged the Volt Reg to the Alt? Crimping the diode will work well as circuit uses very low current. Then tape over connection and diode.

 

Yes the engine shut down every time the line was unplugged. Plug it in and engine doesn't shutdown so this has to be the engine. Lost my tool to crimp with so on my way to get a new one and install it.

 

Not trying to confuse the issue, I believe the diode install is really a patch (which works), and would install it anyway because it wont hurt anything being there. As stated before, I would repair all ground straps--engine to frame-body to frame-grill/fenders to frame. This proceedure magically fixes inop tail/marker/turn pblms and instruments and dash lights begin to work again and all sorts of neat stuff.

 

Oh all the ground straps were replaced when I replaced the engine like 2 weeks before I got this issue. Then I thought I had fixed it, but apparently I didn't and the diode is in and the Jeep shuts down all the time now. I always look at the most apparent things first and was just out of ideas when I posted this thread.

 

Good show. Happy for you.