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  Topic Review (Newest First)
09-20-2021 05:31 AM
fishadventure (Power ‘coming out’ is going to be 50K volts when the engine is turning over…)

But you say when you hit the key everything blacks out. New cables: good. But did you remove and clean everything at the dipstick negative(-) connection and replace the firewall ground strap?
Your symptom is usually caused by a bad connection. Or a bad battery. Or a bad starter.

Hit the starter with a hammer; try to start it; report back.
09-19-2021 04:03 PM
Jeepfather I replaced both battery cables and the connections are clean on the battery and at the ground. I went ahead and replaced the coil as it said AMC on it and appeared to be original. I have power coming into the coil but nothing coming ou so I believe it is not getting signal to fire. Please let me know if this thinking is incorrect. Thanks!
09-16-2021 07:17 AM
vadslram
Quote:
no power to anything. I replaced the relay on the firewall. I immediately have light but when I turn the key to start it I get a click and then no power to anything again.
Supply issue. Check all the cables from the battery and their connections. Probably the ground side. If there is corrosion at the connections limiting the physical/electrical connection and you get a big draw like a starter it will melt the final bit of connection just like a fuse.
09-06-2021 06:39 PM
cas6969 The last two "heat up and shut off" problems I had (with non Jeeps, but older rides) were both distributor innards, pickup and ignition module respectively. As you say, coil would be a likely suspect as well.
09-06-2021 03:10 PM
jay-h
Quote:
Originally Posted by laybackman View Post
Ran for 5 minutes, crapped the bed and now no spark.....coil issue possibly. I'll do some research (in English: I'm freakin' 73 tomorrow and can't remember crap!
Step wise, check the power at the coil. That could be your problem. Someone mentioned a ballast resistor, but many have a length of resistance wire which is bypassed during cranking.

Historically the ballast resistor was required in point ignition to prevent a spark when the points closed (spark is only desired when the points open) but it was carried through some pointless ignitions, perhaps for the same reason. In any case you should have 12V to the coil during cranking and about 8 during run position (engine does not have to be actually running to check that)
09-06-2021 08:56 AM
mark1305 My 89 4.2 had a ballast resistor (and a bunch of other stuff that I said "Good riddance" and installed a CRT distributor). IIRC the ballast was a square ceramic looking thing about the size of some of those square aluminum factory splices in the harness on the firewall.
09-06-2021 04:36 AM
fishadventure layback: doesn’t that also have a ballast resistor and ‘module’ box? Or was that gone by the YJ years? It’s just that both of those can do “that” so…
09-05-2021 05:09 PM
laybackman
Quote:
Originally Posted by Jeepfather View Post
Ok. I have not worked on it in over a month until today. Replaced the battery cables and the solenoid on the firewall and boom it starts! It ran for about 5 minutes and died. Now it turns over and I have no spark. When I replaced the positive cable the new one running to the solenoid on the firewall is smaller diameter. Could this make a difference? Thanks,
Ran for 5 minutes, crapped the bed and now no spark.....coil issue possibly. I'll do some research (in English: I'm freakin' 73 tomorrow and can't remember crap!
09-05-2021 04:36 PM
Jeepfather Ok. I have not worked on it in over a month until today. Replaced the battery cables and the solenoid on the firewall and boom it starts! It ran for about 5 minutes and died. Now it turns over and I have no spark. When I replaced the positive cable the new one running to the solenoid on the firewall is smaller diameter. Could this make a difference? Thanks,
07-26-2021 01:24 PM
laybackman Remove both battery cables at the battery. Naturally check the connectors to see if they are clean and in good condition and are on properly. Then grab each one by the connector and twist it back and forth rather vigorously at least a half dozen times. Now grab them and bend them out shape pinching the cable back onto itself. Put the cables back on. IF the battery is fully charged hit the key and see what it does. If it has a fully charged battery and it fires up I would also suspect that the cables are all green underneath the insulation......Replace them!
07-22-2021 11:02 AM
jay-h A corroded connection can do this. When cold it has reasonable continuity, however once you put load through it, it heats up locally and the resistance goes way up.

with key on, check voltage drop between battery + and various points along the way.
07-22-2021 10:45 AM
timatoe I'd start with checking voltages into and out of the ignition switch (the actual switch behind the dash on top of the column) and checking the condition of the battery cables (they're known to corrode inside the cable).
07-22-2021 10:41 AM
Jeepfather
Odd power problem

Ok, I have an electrical issue. Itís a 1989 with the 4.2 and a manual trans. I went out the other day and no power to anything. I replaced the relay on the firewall. I immediately have light but when I turn the key to start it I get a click and then no power to anything again. I unhook the battery then hook it back up and I have lights again. Turn the key to start and it all goes dead again. This is driving me nuts. Any ideas? Thanks and any help is appreciated!

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