Mechanics

CJ7

1984 Jeep Cherokee • V8 4WD Manual •

Jeep Cj with 304, have to replace ignition coil often. What is causing this problem?
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Cfengineer
February 12, 2011.




Tell me this: Do you have 12 Volts at the POSITIVE SIDE of the COIL, while it's running. What do you have there?

I can help you with this and any other CJ problem you have, if you'll hang with me!

I have answered MOST of the CJ5 and 7 Questions for the last 2 years.

Keep replying here at this Post (any CJ Question you have.I do not know everything. But I do try hard, and with personal pics) I will continue to reply (forever, I presently have the largest---on-going Car (CJ) Answer going at this site's history. Still going!)

I will link you there, when you reply here, Lot's of good CJ info in it!

Waitin' on you Buddy

The Medic


CJ MEDEVAC
Feb 12, 2011.
Well it won't start unless I go buy another coil, so I'll have to get that tomorrow, but I can tell you with the key on, it is getting 11volts. This is my fourth coil and I have replaced the ignition module once already back in December. Cranked up fine a couple of weeks ago and I let it run for 20 mins or so then shut it off. Came back about an hour later and it started right up again but died shortly there after and won't hit a lick. I put an old coil back in it today and it started up fine but ran for about a minute and then died again. I appreciate any advice you have!


Tiny
Cfengineer
Feb 12, 2011.
Ok this time, insure you get the coil that states: FOR USE WITH EXTERNAL RESISTOR!

We will get into that DEEPER, when I get back from the store!

Is your rig stock, or has it been Scavenged over, and "Rigged" over the years---This is important for me to know, so that we can get you back right.

Any other Non-Stock Modifications?

I'm here for the long haul!

Don't run it if you do not have to, till we get you straight!

Your Turn. Wifey hurrying me along now!

The Medic


CJ MEDEVAC
Feb 12, 2011.
2nd thought, do not get the coil till I find out about possible Mods!

The Medic
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CJ MEDEVAC
Feb 12, 2011.
Yes this is a complete rebuild. Though the engine had been rebuilt prior to my ownership. This is a 84 cj7 and that year did not offer a v8 engine. So nothing is necessarily stock. I am not at home either but almost certain the coil had text on the side indicating use of external wire resistor. But will check again. This is a toy, so I only drive it on the weekends weather permitting.


Tiny
Cfengineer
Feb 13, 2011.
Thanks for the Update---Does change things. Just a little!

Get something straight--- JEEP NOT = TOY. JEEP = The Biggest Mechanical Break-Thru, Man Has Ever Devised!

Gonna Send 2 answers. To keep stuff separated. Don't jump in, till I send second!

1st Sounds as though you are getting full Battery Voltage to the Coil Continuously--WRONG!

Originally you had a RESISTANCE WIRE that Reduced Coil Voltage. For LONGEVITY. NOW YOU DO NOT.

There are 2 things we need to FIX

1) Reduce Voltage to the coil, when Jeep is running---No Problem!

2) Install a device to do this task.

3) Get FULL BATTERY VOLTAGE TO COIL, when Starting only. This may still be intact on yours--if not, we will run another wire to solve that issue too!

I need to know if your Jeep Operates Correctly (Starting and running) With your Key Switch?

OK, 1st pic----My '77 CJ 5 running (This may vary slightly)---Voltage to Coil. Continued.


CJ MEDEVAC
Feb 13, 2011.
OK--The resistance wire looks just like a wire, if it's just been "SNIPPED" and spliced onto. It still has a little resistance---WE DO NOT WANT THAT!

If this is the case--the POSITIVE wire to your coil, needs to be traced back toward the Key---NOT THE "I" Terminal of the SOLENOID (If it still goes to the solenoid--THAT IS GOOD!) <<
As you follow this wire, ORIGINALLY it will splice into Maybe 2 other wiresThat is our starting Point (the other wires are not resistors), to run a. Let's say 16 Gauge wire, back to the coil>>>>>>Except we are gonna install a "BALLAST RESISTOR". Somewhere in that line---IT REDUCES VOLTAGE!

If you are not already voltage of battery (due to Your Modifications)Test your "NEW"starting point against battery voltage, at the battery----KEY ON--JEEP OFF

Let me know how this works out---We are FLEXIBLE!--Can change!

We must select a good place for it---It get HOT!--MUST BREATH!---OUT OF THE WAY. Its ceramic with a wire coil in it, and FRAGILE!

This too, can go bad. If it does, you can simply connect or jumper across the wires (Giving full voltage once again, to LIMP back in. Basically what you have NOW!)

The Wire Coil in this thing is fragile, since it gets HOT sorta in one spot. Thats why they went to the Long Resistance wire, in order to spread out the "Warmth", throughout the entire wire.

JUST REMEMBER YOU HAVE THIS INSTALLED. KEEP IT IN PLAIN SIGHT. SO YOU CAN BYPASS IT IF NEED BE!

This is my 1946 WILLYS JEEP (this pic), HIS NAME IS "WILLY". Manly names for manly vehicles.'77 is "Mr. Jeep". No "Sissy" Stuff around here!

IN THIS PIC, I converted (Rather wired completely from nothing, As I threw the entire Original body away [shot], and installed a fiberglass one) It was 6 Volts---Now 12 Volts. Still got points in the distributor.

We will discuss "I" Terminal next!

Your Turn

The Medic


CJ MEDEVAC
Feb 13, 2011.
All Righty Then

You ain't come back yet.I got time to hunt and peck awhile. It's 2 in the morning here.

I'm gonna throw in explanations of your solenoid. This is gonna be a pick of Mr. Jeep's with YELLOW writing on it. Also one with Willy's solenoid with Numbers and letters on it.

Both are connected IDENTICAL, 'cept Willy's may have fewer accessory wires on the POSITIVE BATTERY CABLE SIDE of it.

I CAN SEND YOU A SIMPLIFIED WIRE DIAGRAM (THAT I CONSTRUCTED) OF WHAT YOU ARE DEALING WITH. IF YOU DESIRE.

YOU MAY SEE IT BETTER IN YOUR E-MAIL. SO IF YOU WANT TO, CLICK ON MY NAME AND SEND ME A MESSAGE CONTAINING IT (IN MESSAGES, IT WILL NOT BE BROADCAST WORLDWIDE!)

THE BIG REASON I DO NOT WANT YOU TO JUST CHANGE TO A DIFFERENT COIL IS, LATER YOU WILL FORGET (OR SOMEONE ELSE WILL) AND YOU WILL BE BACK IN THE SAME BOAT.'CORSE THAT COULD HAPPEN WITH THE BALLAST RESISTOR TOO! THAT'S WHY I SAID KEEP IT IN PLAIN SIGHT! SOME "COIL HOLDERS" HAVE A TAB WITH A HOLE STICKING OUT FROM THEM, YOU CAN BOLT IT ON, RIGHT BESIDE THE COIL, IF YOURS HAS ONE.

THE PICKS AND EXPLANATIONS WILL EXPLAIN WHAT THE STUFF IS ON THE SOLENOID. AND IF HOOKED UP EXACTLY AS MINE, YOU CAN "REMOTE START" OR "CHEAT THE START CIRCUIT" OR "BUMP THE ENGINE". USING A SCREWDRIVER. ACTUAL STARTING REQUIRES THE KEY TO BE IN THE "ON POSITION".

BUMPING, THE KEY NEEDS TO BE OFF AND THE "COIL TO DISTRIBUTOR CAP HIGH TENSION WIRE" REMOVED, TO PREVENT ACCIDENTAL STARTING. INSURE YOU ARE IN "NEUTRAL" OR "PARK" WITH THE TRANSMISSION.

AT LEAST YOU WILL KNOW WHAT EVERYTHING DOES. And WHEN AND NOT WHEN, IT SHOULD HAVE VOLTAGE.

I went back to another answer to get this. I Copied, Pasted, and put the pics back in.'Cause I hunt and peck slowly, and try to proofread several times before I submit.

IT WAS SORTA INTENDED FOR SOMEONE WITH A "NO START ISSUE". SOME OF THIS AT THE BEGINNING, IS FOR OTHER VEHICLES (NEWER TYPE). WHAT YOU NEED IS TOWARD THE END.

LOOK AT AND UNDERSTAND "I" TERMINAL---IT IS IMPORTANT AT START-UP!

OK the 1st part was sorta for other applications, but you will see what I intended for a CJ. Ask me questions, CJ fixin' is my Crusade at this site! I will assist you on a more personal, "HOLD YOUR HAND THRU IT ALL!" Level, than some of the other fellers. See other CJ5 & 7 questions in the forums, you will see the extent I go to assist CJs. THERE IS GOOD INFO YOU MIGHT NEED IN THERE, TOO!

CHECK YOUR FUSES!---YOUR OWNERS MANUAL MAY SHOW YOU LOCATIONS THAT YOU KNEW NOTHING ABOUT!

REMOVE AND REPLACE "SUSPECT" FUSES SEVERAL TIMES--THIS MAY SCRAPE OFF CORROSION AND GIVE THEM BETTER CONTACT!

THIS WILL WORK FOR YOU, PROVIDED THAT YOUR BATTERY IS GOOD---OR YOU CAN BE JUMPED OFF!

REMEMBER "NEW STUFF" CAN BE BAD TOO!

YOUR STARTER MAY BE BAD!

YOUR SOLENOID MAY BE BAD!

Try the stuff below (actions), Even if this isn't your system.

Yours may not look like this, but TAKE STUFF LOOSECLEANTIGHTEN WELLDO NOT JUST PASS IT OFF AS, "IT LOOKS GOOD".

Do not leave off where the Battery cables connect to the Battery clamps! (Not the posts, the "squeeze connections" on the wire) Do them too!

While you are at it, Both ends of Pos cable, Both ends of NEG cable.

If you still have the problem. Follow Battery Positive cable to find the Solenoid.

Clean and tighten the starter connection!

My stuff may be OVERKILL, but at least you will know what everything is and does.

Like my newly made "NELSOMATIC" stuff? I am cyber stupid, and did that! Keeps me from hunt and pecking so much!

Follow POS BATT CABLE, It will end up at MR. SOLENOID, yours may look different, but function is the same

Insure you are hooked up correctly and tight.

Make sure "S" WIRE is attached to the Solenoid

"OLD FORD TYPE" SOLENOID SYSTEM, YOUR ACCES, MAY VARY (This was really intended for Jeep CJ People!)

1) POSITIVE CABLE FROM BATTERY

2) OUT TO STARTER MOTOR

3) ON MY JEEP, THIS GOES TO THE ALTERNATOR

4) THIS FEEDS MY FUSEBOX (ALL OF MY ACCESSORIES)

5) "S" WIRE IS FROM KEY, 12V ONLY WHILE YOU ARE "CRANKING"

THIS WIRE ACTIVATES THE SOLENOID'S ELECTROMAGNET, WHICH IN TURN, CONNECTS---A and B INTERNALLY (ONLY THE 2 LARGE GAUGE CABLES CAN HANDLE THE AMPERAGE THE STARTER "PULLS").

WHEN THE SOLENOID IS ACTIVATED, IT THROWS 12V TO STARTER USING THE LARGE GAUGE CABLES (1) POS FROM BATT--THRU SOLENOID INTERNAL CONNECTION--(2) TO THE STARTER, WHILE KEY IS IN "CRANKING" MODE.

THIS IS THE TOTAL REASON FOR A SOLENOID, BECAUSE IT WOULD NOT BE PRACTICAL, TO RUN THE HEAVY CABLES TO AND FROM YOUR KEY SWITCH.

6)"I" WIRE, FEEDS COIL "FULL 12V", ONLY WHILE "CRANKING", AFTER YOU RELEASE THE KEY, THE COIL REVERTS BACK TO REDUCED VOLTAGE (resistor wire), SUPPLIED BY YOUR KEY IN THE "RUN" POSITION."I" DIES, when you release the key.

7) "SOLENOID MOUNT" [BODY GROUND], UNIT MUST HAVE A GOOD GROUND (BATT. TO ENGINE, ENGINE TO FRAME, FRAME TO BODY [ALL MUST CONNECT, SOMEHOW. But BATTERY to ENGINE 1st!] )

(3 and 4, ON MY 1946 WILLYS JEEP) ARE FUSABLE LINKS, ALL ARE NOT MARKED, MY #3 IS, #4 IS NOT. ITS SORT OF A "WIRE" FUSE.

IF THEY ARE GOOD, TUGGING ON THEM WILL BE JUST LIKE A WIRE, WHEN THEY ARE "BURNED UP", THEY WILL STRETCH OUT LKE A RUBBER BAND.

If your SOLENOID is good---Just not getting a "Signal" from the Key--We can test that too! (Then you will know which direction to chase this problem. Toward the key! [Ignition switch])

"S" is the wire that activates the Solenoid----we can sorta cheat it!

Regardless what you do to cheat it, You are suppling 12 VOLTS to the "S"('s) terminal on the solenoid. This is momentary as if you are cranking with the key

STAY CLEAR OF MOVING PARTS!IN PARK--OR EMERGENCY BRAKE ON!

I prefer a "Remote Starter Switch"

A Jumper wire momentarily touched or a Screwdriver touching POS BATTERY or POS BATTERY CABLE to the "S" terminal will by-pass the wire from the key

This will for sure let you know whether its a Solenoid problem or a Key ( ignition switch not delivering 12 Volts)

This will start your rig if your key is in the "ON" Position

IF YOU HAVE A CJ 5 OR CJ 7---YOUR WIRES SHOULD BE HOOKED UP, EXACTLY AS MINE ARE, IN THE PICS!

JEEP CJ GUYS!--If you changed your coil and did not get the one that says, "FOR USE WITH EXTERNAL RESISTOR ONLY". You NEED TO GET THAT ONE! You have just "DOUBLED" your resistance (w/ one with a internal resistor), and DO NOT HAVE ENOUGH VOLTS TO MAKE IT FIRE! (Your resistor is a "RESISTANCE WIRE" going to the coil already!)

Please Reply, Good or Bad

I WILL RE-EXPLAIN ANYTHING, DIFFERENTLY, IF YOU WANT ME TOO!

I'M HERE TO HELP, THIS IS MY HOBBY, I AM A MEMBER HERE, JUST LIKE YOU!

YOUR TURN. Now it's 3 in the morning!

THE MEDIC


CJ MEDEVAC
Feb 13, 2011.
Ok I'm back. I have checked on a few things that you asked about and tracked some of the wires from the coil. First things first, the coil I have does require and external resister. With that said I tracked the positive side, one red and one blue wire. The red leads back to a splice in which those wires run to the ignition module and the other through the fire wall. The blue leads back to a lead on the carburator. Now please be aware I know just enough about all of this to be dangerous! I put all of this back together just as the previous owner had it, so I am not sure if he/they had it right. With that said the negative side of the coil has a green wire and it also leads back to the firewall. On the solenoid, the "I" terminal has nothing on it. Note, all wires seem to be intact and do not appear to have any shorts ir bare places in them.

From your reply, if I understand correctly I need to go purchase an external ballast resister? Is this correct? Also, I am beginning to understand that a full 12volts at the coil is what is causing them to go bad, correct?


Tiny
Cfengineer
Feb 13, 2011.
Ok. I went and got a new coil and ballast resister. I put the new coil on and nothing. In the past a new coil would solve the problem for a lttile bit. Anyway. Disconnected the coil again and checked volts on both coil leads again without them connected to the coil. The red/blue wires that feed the positive side read 12 volts. The green wire hooked to the negative side read 4.5 volts? Is that normal?

Things that I know: The plugs were changed last spring
New coil
New dist. Cap
new ignition module
Getting Gas(fresh gas)
Started fine three weeks ago

What I don't know.
Why this dang thing won't start and what the next step is.

Look forward to more advice.


Tiny
Cfengineer
Feb 13, 2011.

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