Engine Spark issue ...

[edons]

I got my CJ7 for free about a year ago. fixed it up so i could drive to school and work. now that its summer, i changed out the engine from the AMC I4 to an AMC I6 in good condition. I'm now trying to start it to make sure it works, but I cannot get a spark. I've tried everything I can think of. The engine turns over but I can get no spark.
What I've tried so far:
1. replace starter solenoid
2. replace ignition coil
3. trace every wire back to the solenoid, steering column, or engine control unit.
The only thing I can find thats not right is that, when the key is turned to start, the voltage into the ignition coil does not jump from 6v to 12v like its supposed to. The voltage just either remains at 6v or drops to 0. I need help, please!

 

[elwood blues]

What year is the L6 that you're using? Does it have an ICM (ignition control module)? Looks like this.

That could be bad and shorting your coil voltage to ground. It could possibly be your distributor, but I doubt it. Unless it's in your ignition switch at the bottom of your steering column.

 

[IOPort51]

Are you referring to the wire on the coil coming from the ignition??
If so you are on the right track, check the ignition switch again to see why you do not have full voltage to the coil with the switch on.

I am hoping you have learned that it is possible to diagnose most problems and know for a fact what part must be replaced. Replacing parts until it works can become very expensive.
This is an important lesson and a major step on the road to enlightenment.
you are doing well.

 

[edons]

What year is the L6 that you're using? Does it have an ICM (ignition control module)? Looks like this.

That could be bad and shorting your coil voltage to ground. It could possibly be your distributor, but I doubt it. Unless it's in your ignition switch at the bottom of your steering column.

the guy i bought the L6 from didnt know what year it was but it does have an ICM. I just took it to be tested at autozone, it passed fine. what do you mean by the ignition switch at the BOTTOM of the steering column?

 

[IOPort51]

the key moves a rod that operates a switch under the dashbut the switch is actually on the top side of the column I think.

when working behind the dash there are two things I have learned. First always disconnect the battery, and 2nd it is not that difficult to remove the bolts holding the dash and pull it away a couple of inches. Hang the passenger side from a wire to the top of the windshield frame and it makes access to the wiring 100% easier.

 

[edons]

I'm gonna try that. i'll get back to you.

 

[edons]

the key moves a rod that operates a switch under the dashbut the switch is actually on the top side of the column I think.

when working behind the dash there are two things I have learned. First always disconnect the battery, and 2nd it is not that difficult to remove the bolts holding the dash and pull it away a couple of inches. Hang the passenger side from a wire to the top of the windshield frame and it makes access to the wiring 100% easier.

I didnt find anything wrong under the dash, although it was that difficult to remove the bolts holding the dash on. I got the bolts off with a grinder in the end. I was also wondering if my Engine control module might be affecting the startup sequence. Because its originally programmed for an L4 and it now has an L6. I just cant seem to find anything on the internet about it and nobody seems to know what i'm talking about when I say ECM.

 

[albatros 3]

If I remember right, isn't there a safety switch at the clutch? Is the coil getting power?

 

[edons]

Yes the coil gets 6v. but it's supposed to jump to 12v when i turn the key to start.

 

[IOPort51]

actually, it is supposed to get 12 V when the switch is "on" the 12 V to start goes to the solenoid. As far as I know the wire to the coil does not have anything to do with the ECM. You have the wrong wire or the switch is not delivering 12V to the coil. You could always try "hot wiring" the coil by running a wire fron positive on battery to the hot side of the coil. this should give you spark when the engine is turned over.
Is there a difference between the 4 cylinder ECM and the 6?? check the part numbers .

Yes the coil gets 6v. but it's supposed to jump to 12v when i turn the key to start.

 

[edons]

Well, I found the original factory jeep manual online so i checked the coil and it is supposed to get 6v, 12v when it starts. I do agree that ECM has nothing to do with the coil, but I've been fighting the computer from the beginning so I removed the computer and performed a nutter bypass. I now have a new problem, my solenoid makes a loud buzzing noise when I try to start it. I haven't done anything to it but remove the computer, and when I tried to put the computer back afterwards, the solenoid still made the buzzing noise. I'm getting very desperate because I need this thing to drive by saturday or its my ***.

 

[edons]

Are you referring to the wire on the coil coming from the ignition??
If so you are on the right track, check the ignition switch again to see why you do not have full voltage to the coil with the switch on.

I am hoping you have learned that it is possible to diagnose most problems and know for a fact what part must be replaced. Replacing parts until it works can become very expensive.
This is an important lesson and a major step on the road to enlightenment.
you are doing well.

IO is a genius! I hope. I retested the ignition switch and found a huge voltage drop when the key is at start. 12v in, but only 3.5v comes out. so now I need to know: How do i fix the issue if its inside the ignition switch? how do i remove the switch?

 

[edons]

In case anyone cares: my jeep is running again. I drive it to and from work now.