Sporadic electrical issue - HELP!

719 Views 5 Replies 4 Participants Last post by Got it at last, Jul 30, 2017

mugrin

Discussion Starter · Jul 28, 2017

This is going to be sort of a long post, but it's only because I want to be thorough and also because I have tried a LOT of things before resorting to asking for help on a forum. I know how to use google, I know how to use search function, I have finally hit a wall.

So, 1989 Sahara 258. I'll list as many things as I can remember that I've done to her since getting it last summer;

- Nutter bypass
- New exhaust - Manifold, pipes, muffler.
- Head gasket / head machine work
- Auto tranny rebuild
- Plugs, wires, cap, rotor
- New coil for a month (Accel), then reverted to original coil (This could be important.)
- New ignition switch. (Not lock cylinder.)
- Confirmed / created good ground anywhere I could find it.
- Battery

So now the issue; Everyone once in a while, the jeep, when I start it, will suddenly shut down from ignition loss. I've confirmed this by using a multimeter on the ends of my spark plug wires.
It is not a fuel issue.

When trying to turn the engine over again when it does this, it seems to turn over really fast, and never gets ignition. And when I turn the key off, it will sometimes make a little sound as if almost firing up.
Then, after 20-40 minutes of sitting, the jeep will start right up and run as if nothing ever happened. But it won't ever run long, the longest I got it to idle since this problem started was about 30 minutes.

The problem is sporadic, sometimes it happens after 20 seconds of being started cold, sometimes 2 minutes.

But I'm out of ideas on what to check / replace / try.

Please help!

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Luckymac

· #2 · Jul 29, 2017

Some parts, particularly the parts made offshore, are faulty right out of the box.
What I would try is a KNOWN GOOD ignition switch. Do you have any Jeeper buddys that might loan you their switch to try?

You mention the coil might be important. Did the same problem occur with the Accel coil?

You may have a bad Ignition Control Module. Before I bought an ICM, I would buy a HEI if you don't have emissions testing where you are, or you if you think can get the HEI past the inspectors.

Check the Factory Service Manual to see if there is a test for the ICM (the module hidden down below your windshield washer bottle).

Other posters may have more input.

Good Luck, L.M.

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Bigg Skillet

· #3 · Jul 29, 2017

All of the things you listed are symptomatic of a crank sensor gone bad.....Here's a link that might help you.

Crankshaft position sensor for the Jeep Wrangler. Test and change how to.

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mugrin

Discussion Starter · #4 · Jul 29, 2017

I had no reason to think my switch was bad, but I replaced it with a brand new one anyway and the problem persisted. I'd like to go other routes before messing with that again. I don't know if you've ever removed/replaced a YJ ignition switch, but it's a project I'd never like to do again.

As far as the coil, I mentioned that it might be important because about 2 months after I put that coil in, the problem started. Part of me wondered if the coil had something to do with it. Although the problem persists with the original coil too.

No emissions where I am, HEI is a route I can take.

I'll look into the crank sensor too. Thanks for the ideas!

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Got it at last

· #5 · Jul 30, 2017

Bigg Skillet said:
All of the things you listed are symptomatic of a crank sensor gone bad.....Here's a link that might help you.

Crankshaft position sensor for the Jeep Wrangler. Test and change how to.

Your 89 should have the 4.2, carbed engine, no CPS.

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Got it at last

· #6 · Jul 30, 2017

mugrin said:
I had no reason to think my switch was bad, but I replaced it with a brand new one anyway and the problem persisted. I'd like to go other routes before messing with that again. I don't know if you've ever removed/replaced a YJ ignition switch, but it's a project I'd never like to do again.

As far as the coil, I mentioned that it might be important because about 2 months after I put that coil in, the problem started. Part of me wondered if the coil had something to do with it. Although the problem persists with the original coil too.

No emissions where I am, HEI is a route I can take.

I'll look into the crank sensor too. Thanks for the ideas!

x2 with L.M. Go the route of the HEI. You can solve a boatload of other problems by bypassing the 30 yr old computer. once you get down that road you will probably lose the stepper carb also if you don't have to deal with emissions.

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