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Unread 05-21-2010, 09:01 AM   #16
jeeperscrepers
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1979 CJ7 
 
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After changing my fuel cap haven't had any issue since Saturday. Hoping that was the problem...bad cap.

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Unread 05-21-2010, 11:34 AM   #17
Ken4444
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Quote:
Originally Posted by Mike Romain View Post
The gas tank does need to be vented. The vent is the charcoal canister and it has a $2.00 air filter on it's bottom that when plugged with dirt puts a vacuum on the gas tank which will cause stalls and bogs. Not usually at idle though.
Mike, is there anything about CJs that you don't know?
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Unread 05-21-2010, 01:25 PM   #18
Mike Romain
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Quote:
Originally Posted by AlbertGaines View Post
I also have been having ignition (I think) shutoff issues. Shuts off after running for some time. Starts off with a small hickup then gets worse and will shut off. Can restart after some effort and may run fine for a few minutes. Will not show problems in the driveway after getting it home and trying to find the issue.
After it cools off it will start and not show any signs of the problem until some period of driving time.

Acts like Ignition Module.
I have replaced the Iginition Module 3 times, Coil, ignition switch, manual fuel pump, put in a new distributor last night. I hope it is the pickup getting hot and maybe being saturated and sending a bad signal back to the IGM.
The pickup was $20 the rebuilt distributor was $60, so I replaced entire distributor.
Keeping fingers crossed.
Next time maybe try cracking open the gas cap and see if that fixes it.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
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Unread 05-25-2010, 02:22 PM   #19
AlbertGaines
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Ok so I have now replaced the distributor, still the same. Drove it this morning and after about 45 minutes it starts jumping and wanting to cut off. I removed the gas cap and no effect. After continued driving it will cut off. It can take several attempts to restart. After restarting it may run fine for a mile or maybe only 100 yards and it will act like it has lost fire or gas.
While it was acting this way this morning, I got it home and shut it off and replaced the Ignition Module with a brand new one. Started it back up and it still was running the same way, wanting to cut off after a 1/2mile and then cutting off.
I have replaced the:

Ignition Module (3times)
Iginition switch
Coil
Disributor with pickup
Fuel pump.

Any other ideas?
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Unread 05-25-2010, 07:03 PM   #20
Torxhead
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Albert, you have really covered the usual suspects. It is possible you could have a frayed connection somewhere. You might try jiggling a few wires around while the engine is warmed up and idling. If it was the icm, it would be warm to the touch. If so, that would mean a bad connection could be killing it. Like if any of the wires coming from the distributor had a weak connection, a little moving around of the wires could shut it off. Same with the icm. You could take in the other icms that you have accumulated for testing.
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Unread 05-25-2010, 07:28 PM   #21
guysnydr
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Yeah, this is a tough one! My 79 did the same thing with the 258, I would be driving down the road and all of the sudden she would just die, I could throw it in neutral and it would always start right back up again, even when still rolling. I did notice it more often when hitting a bump also. I am convinced it was electical or ignition, I replaced the coil, the ICM, the rotor, the cap, the plugs the wires, the pickup inside the distributor and the magnetic spur gear and never did figure it out. My next step was to double check the gap between the spur gear and magnetic pickup and if that failed then replace the whole distributor but then I decided to do a small block chevy swap and quit messing with it. My problem COULD have been in the wire harness somewhere but when I rebuilt the Jeep last year from the frame up I went over the entire wire harness very well. I wish I was help to you but I never did come up with a solution, I was also going to replace the distributor with an HEI if I kept the motor in but didn't get that far. The stock ignition system doesn't seem to have a very good overall reputation. Anyway, I hope you figure it out, I never was able to.
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Unread 05-25-2010, 07:42 PM   #22
AlbertGaines
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Does anyone have a source for the harness side connectors used at the distributor and the module? My thought is to make a section of the harness that goes to the distibutor to the module.
This unit has 2 plugs.
Output plug has 4 wires that run from the distibutor to the module; 2 for the distributor pickup, 1 ground and a green wire to the coil.
Then 2 input wires to the module on a seperate plug.

Thanks for all the ideas.
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Unread 05-27-2010, 05:13 AM   #23
Mike Romain
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The stock coil connector can cause that. The clips get weak or stretched and the wrong bump can up and kill it.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
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Unread 05-27-2010, 07:35 AM   #24
Jeepit85
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I too am going thru a motor that is hesitating. It never dies just runs rough at times. I am checking all my grounds this weekend.
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Unread 05-27-2010, 09:08 AM   #25
Ken4444
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Does anyone have a list of the factory ground wires/straps? It would also be helpful to have a list of user-added ground wires that are good to have. It would be helpful to have a sticky / definitive CJ grounding thread. I know all that information is already contained in dozens of existing posts. It would be nice to have it in one place.
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Unread 05-27-2010, 09:26 AM   #26
Mike Romain
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Quote:
Originally Posted by Ken4444 View Post
Does anyone have a list of the factory ground wires/straps? It would also be helpful to have a list of user-added ground wires that are good to have. It would be helpful to have a sticky / definitive CJ grounding thread. I know all that information is already contained in dozens of existing posts. It would be nice to have it in one place.
Stock my 86 CJ7 had a battery cable to the engine head and from a head bolt, a mesh strap to the firewall. One engine mount also had a mesh strap from the block side to the frame side.

Then there was the computer grounding, mine was on top of the tranny cover plate on a bolt.

Jeephammer has a post up on grounding the starter bolt and then the head (if your battery cable goes to the block) and a ground on the alternator case ('real' good idea, have seen many brackets with bad grounds) and a ground on the black wire coming out of the distributor to ground the ignition module (it uses the hold down foot otherwise) and a ground to the tub. I think that is it.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
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Unread 05-27-2010, 10:58 AM   #27
Jeepit85
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Thanks Mike. That's a big help for me for the weekend!!
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Unread 07-12-2010, 05:04 PM   #28
AlbertGaines
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Quote:
Originally Posted by AlbertGaines View Post
Ok so I have now replaced the distributor, still the same. Drove it this morning and after about 45 minutes it starts jumping and wanting to cut off. I removed the gas cap and no effect. After continued driving it will cut off. It can take several attempts to restart. After restarting it may run fine for a mile or maybe only 100 yards and it will act like it has lost fire or gas.
While it was acting this way this morning, I got it home and shut it off and replaced the Ignition Module with a brand new one. Started it back up and it still was running the same way, wanting to cut off after a 1/2mile and then cutting off.
I have replaced the:

Ignition Module (3times)
Iginition switch
Coil
Disributor with pickup
Fuel pump.

Any other ideas?
So I think I have solved the mystery.
I got to thinking, (sometimes dangerous) maybe this is not a issue from driving relating to heat. Maybe it is just time that it has run. What else could it be.
You did not think this would be a short answer. heck, I chased it for months.
So I put a clear inline fuel filter at the input of the fuel pump. After running a while it shut off. The fuel was coming into the filter but the filter was dry excepting for the input gas.
The CJ7 has a bypass on the fuel filter that sends extra gas back to the tank. Keeps it from vapor locking.
So I clamped this feed back line closed at the filter, and she kept running.
So I had a lead in the case. I ran a long fuel line into a 5 gal gas can and connected to my fuel pump, with feed back line unclamped and she ran OK.

Solution, replaced tank and sending unit with new filter. Strainer on pickup in tank was stopped up with very fine stuff, and had some trash in the tank.
After a period of time of running this extra stuff would stop gas from getting thru the glogged filter.
Oh, I forgot to add, had to do the tank swap 2 times. Went to a new plactic type tank and it leaked. The new sending unit float had a hole and sank.
2nd tank and sending seemed to have fixed it.

Thanks to all.
Jeeps, you got to love them!!!!!
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Unread 07-12-2010, 07:03 PM   #29
Daladim
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Quote:
Originally Posted by Mike Romain View Post
The stock coil connector can cause that. The clips get weak or stretched and the wrong bump can up and kill it.
This is what I was thinking as reading the posts in this thread. I had the same exact problem as everyone else has described. Intermittent shut off...

The last time it happened to me, I was on a very long road trip, was 5 miles out of a town late at night and in the wind and rain. The Jeep died and wouldn't start again.

I did a diagnosis, starting with finding out if there was fuel getting to the engine. There was, so I went to the electrical side. Wiggled the coil wires a bit to see if there was any power getting to the distributer, and I saw a spark come out of the coil cap.

One of the wires was completely broke off, and the PO had just stuffed it up in there to get it working again. Small bumps and other vibration was causing it to temporarily lose it's connection. I stuffed it back up in there real good and was able to make it back home.

As soon as I was able, I went to the junk yard and grabbed another one off an old Ford. It works fine now.

I'd definitely check the wires going to your coil cap. This very well could be the culprit. It was in my case anyway.
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