CJ7 ignition problem

jdarrow

Well-Known Member
Joined
Nov 19, 2005
Location
Stafford, Va
I have a 1978 CJ7 with a AMC 360, and a fiberglass tube. I just finished doing the upgrade to run the Ford ignition. I am now burning up the coil and ignition module with 10 mintues with the Jeep sitting at idle. I am running the stock coil out of a 1984 Ford 460, it is a TFI coil that uses the full 12 volts, so I am not running a resistor. I shot all the wires and there are no shorts. Does anyone have any ideas.
 
Pretty tough to diagnose w/o more info, but I'll take a shot.
Unless you are just plain wired into the wrong power supply and getting reduced voltage to the ign system, I would say you have a
Bad or missing ground.

It sounds like your missing a (fairly major) ground somewhere and the system is trying to ground through your ignition.

Especially with a F-glass tub, look at your Jeep as 3 seperate parts, each needs a solid ground.

The Engine/ Trans group.
The Frame
The Body

The glass tub, compounds the problem as all the components in the body need individual grounds as they can't get a ground via a metal body.

If you haven't already done so,
Make sure you have a good, heavy ground from the battery to each of the 3 groups. Even if it means running 3 cables.

One from Batt to Engine/trans.
One from Batt to Frame, and another one from the battery to the junction block(s) on the body you will use to tree off grounds to all the body components.

I am betting once you have good grounds taken care of, your problem will go away.
 
Thanks wbcarver. I think that was the direction he was heading next. You just gave some assurance.

Voltage regulator was a thought as well. Especially since he just got a new high output alt. But I did not think the charging system was tied into the ignition system?
 
Ign is not directly tied to the chg system, but it is effected by it.

Low voltage will burn up electrical parts quicker than enything else.

If he is not getting a good 12v source to the ign system, it will burn stuff up.
When running/charging, you are looking for (aprox) 12.5 - 14.2 volts to the coil pos side and to the module.

Now - it is possible that the new HO alternator is going "full field" and putting out way too much voltage. It is capable of putting out 17 - 24 volts (or more) and that could also toast the ign. But I kind of doubt it.
 
Good food for thought. I can't remmeber if he said he checked the voltage or not last night. They could only get the motor running for about 10-15 mins. till the ignition burnt up. I kinda thought of the alt. too because he did a big upgrade. Jason is the type o guy who upgrades the whole system when one thing goes bad. Thus being said, before all the upgrades..carb, alt. etc.., he was doing good. Then on the trail (Kodak) he started with problems. Ran good up till then. That is why also the thought of grounds came up. Maybe something jarred loose.
 
Thanks for the help Shane I was sleeping. Yeah we shot the wires last night to make sure the alt. was not over chargeing, Also shot all the wires in the ignition system. I beleive it is a ground problem too. I have all the grounds, but I am going back over them today, to ensure a good ground. I am also planning on going back to running a resistor, and running a extra ground off the distributor. I will let it run for a while and see what happens.
 
It's fixed now. I went back to running a ballast resistor, and I added a extra ground to the distributor. Thanks for the help
 
I just got through putting a JY Duraspark ignition setup on my cab truck last weekend. It sounds like that is what you are using. My truck originally had a TFI coil and distributor in it, but without the computer it had no spark advance. I used the standard coil I got at the JY with a Mallory ballast resistor I got from Summit. What is the story on using the TFI coil? No problems using it with the standard ignition module? I found a write up on the net by a guy who used it, but you never know if it worked out in the long run.

DK
 
He ended up doing quit a bit after some research. The original article on the ignition upgrade left some things out. Pretty important stuff to. Ends up after going and redoing the entire ignition, he had a spun cam as well. Atleast his ignition is good now.lol. :beer:
 
drkelly said:
I just got through putting a JY Duraspark ignition setup on my cab truck last weekend. It sounds like that is what you are using. My truck originally had a TFI coil and distributor in it, but without the computer it had no spark advance. I used the standard coil I got at the JY with a Mallory ballast resistor I got from Summit. What is the story on using the TFI coil? No problems using it with the standard ignition module? I found a write up on the net by a guy who used it, but you never know if it worked out in the long run.

DK
Click to expand...

The TFI coil puts out about 2.5 times the usesable spark of the stock coils (jeep), and about 1.5 times of GM HEI. I haven't had any problems using the standard ignition module after I went back to running the ballast reistor.
 
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