The black plastic piece that has a spark plug wire from the distributor to it is the coil. I'll try to share starting wiring diagram for your year on tonight.

 

I sent you a diagram of the starting system. I, also, sent a diagram of the wiring for the e.c.u. Did you need a diagram of the vacuum hoses, too?
In the starting diagram you'll see that the relay for the starter is energized by the ignition in the start position. I'd start your testing at the ignition cylinder.
If you are worried about grounds, then use the resistance setting on an multimeter to measure the Ohms across the wires. Do this from the starter to positive post on the battery as well. Post those resistances here.
Do you have spark when you get it to crank? Also, what are you doing to get it to crank exactly? In the video I couldn't see you touching the relay to initiate cranking.

 

On my '91 I have one large wire at the coil ground bolt. At the ground point on the block between and below spark plugs 5 & 6 I have one large wire and 3 smaller wires.

 

Yours is a different critter than mine. Others might be more help. I did notice your dash volt meter seemed really low, also the cranking speed couldn't be called "brisk". That might matter. If I diagnose "no spark" By checking the gap it will jump, I finish that by holding the coil wire while cranking. Why not if there is "no spark"? Sometimes you might find it's there but weak. If it has spark a shot of starting fluid or a "prime" of some sort would be next. Having a fire extinguisher or a wet towel might be handy here as a backfire can light things.

If it has a crisp blue spark that can easily jump 1/4 inch, and it still won't try to fire with starting fluid or some prime", it could be flooded. Pull a plug plug or two and check. Do know it will cut off fuel completely if you floorboard it, (hold the petal all the way down). Normally to start you don't touch the petal. Floored it will cut off fuel and give max air to remedy a flooded condition.

 

Could not see clearly on the video but make sure that the wire from the coil goes to the center of the distributor. On the video it almost looks as if it does not. Verify alll spark plug wires are in the right place. #1 plug is the front of the engine.

 

The books and diagrams are WRONG! #1 is at 5:00 as viewed from the side, 153624 clockwise. (inline 6 cyl.)

 

You can see where I marked cylinder #1 on the distributor. I put a label on each wire when I changed them to help keep them straight and get the right length wire in the right spot. Going clockwise from #1 the sequence is: 1, 5, 3, 6, 2, 4

It is a quick check to verify you have a good rotor inside the distributor if you have not done that. Wipe out the inside of the distributor with a clean cloth and some carb cleaner to remove any carbon or dirt.

 

Nice video and good work BTW. Do note the NSS on the tranny grounds the start relay you found, only when it's in park or neutral. They often f up, getting gummy or bad contacts. Holding the key over while jiggling the shiftier around park or neutral, if that makes it hit, you found that problem.

On mine, the start relay wont crank it with out that NSS ground.

I looked at your video a third time....there is no harm in pulling the dizy cap, rotor and all of the plug wires and washing them well in the kitchen sink with detergent, (Dawn or equivalent). Dry well. The cap and rotor can take some temp in a low oven if needed. Likely that's not your main issue but that spark is gonna try to find the easiest way to ground. If there is something easier than the air in the plug gap, that's where it will go. (gunk on the rotor or cap might do that) Sometimes watching it in the dark can be enlightening.

 

As an FYI, don’t try to measure the coil secondary (big wire) or spark plug voltage with your multimeter while cranking. The coil secondary voltage can be as high as 40,000 volts on later 4.0’s and certainly higher than the capability of your meter.

Not sure what Don meant regarding “holding the coil wire while cranking”. Although it likely will not seriously injur anyone unless they have a medical condition or device such as a pacemaker or defibrillator you are more likely to injury yourself trying to get away from that wire in a hurry. Why take a chance, Safety first.

 

If you aren't cranking, then the starter motor isn't working right. There isn't a reason to mess with the distributor yet. You need to figure why the starting system isn't working first. Although, I am pro-replacing maintenance parts like the rotor and cap for the distributor. They just aren't the no start problem ... Yet...

 

"If I diagnose "no spark" By checking the gap it will jump, I finish that by holding the coil wire while cranking. Why not if there is "no spark"?

It's a way to be dead nuts sure there is no spark. Playing around with a plug on a wire or holding something near a ground while cranking "should" show you if you have spark or not. If I find their is no spark, as added insurance and occasionally for other information I will hold it and crank, or pull the start cord or whatever. Like you mention actually does no harm, (maybe a little micro pit, and cavity, in a joint it went through), or don't flinch and wack your elbow. Besides, 1/2 the time we end up getting zapped testing it anyway if it's alive.

 

Soooo, first off thanks for all your help so far guys. I wouldn't have gotten this far...

The problem I had before was a simple one. I didn't have the Neutral Safety Switch wire plugged in. I felt like a dummy when I plugged it in and it fired up for the first time. 😂 The NSS fixed my no crank with key problem.

My next problem was back to the no spark issue. I didn't have the CPS bolted down all the way. Once I did that it would start and hold an idle briefly. It felt great to hear an engine with no knocks or taps fire up especially when I got in on a prayer from the junkyard.

But I'm kind of at the end of my financial rope at this point and I'm still not rolling. I think a bad sensor is causing my current issue.

Check out this short video and let me know what you think.

 

HEY! Good to hear back from you. The MAP can get intake manifold vacuum from anywhere. Since it's not plugged into the little rubber dealie on the valve cover side of your throttle body, you might have a vacuum leak there. (down at the base). Plug that o0r fit a tube in there for the MAP.

Suspecting a fuel issue. On mine the pump runs for a few seconds when you turn on the ign to pressurize the rail. (yours does too). Then while it's cranking my start relay powers the pump. (not positive about yours). Then third, after the CPS tells the puter she is running, the puter will ground the fuel pump relay to keep it going. Sounds like you have the first two, but not the third.

In your shoes I'd check the fuses very thourally, including the mini fuses. Might be one of the mini fuses powers your ASD relay. (mine thankfully does not have an Auto Shutdown Relay). That could do that.

Not sure what years.....see if you have a ceramic resistor on the fender near the air cleaner. It can be bypassed, it was only added because people complained about the fuel pump being too loud. Checking and cleaning (Orange?) wires there as well as the resistor itself is a thought.On mine the rear wire goes straight to the pump best as I can figure. Actually if it were the ASD relay it might die sooner, or not start at all. I might pull that rear wire and jump power to it just to see if giving the pump power helps...

For the moment don't worry about the frayed cable. I would pick up another at the JY someday though. It's not really a "kickdown" but has something to do with pump pressure in the tranny or something.

To be clear, power to the fuel pump goes through that resistor, (if you have one). They do fail and also the connections can go fubar. You can jump bat + power right there for the fuel pump, but better to disconnect the front wire to the pump and just power that to test/run it, so as not to "back feed" the circuit. Second, just as you figured out the SPDT relay for your starter, the fuel pump has one also. The puter should ground probably 86 once its running. I suspect it actually is, and the problem has to do with that resistor or it's wires/connections.

Like said the fuel pressure tester is free to borrow, but you need to buy it first, then they let you return it after you use it. (hoping you won't) If you or a friend has a credit card you are all set, just don't loose or break it! (I'd have jumped power to the pump yesterday myself)

If you have access to a real computer there are pictures in the link in my signature.

 

You can "rent" a free fuel pressure gauge from O'Reilly's et cetera. I'd like to know what the pressure is prior to anything, after the key is in the on position for 2-3 seconds, while cranking, while putting/idling, and when it dies.
Ensure that there isn't a crack in the air intake boot and the throttle body is sealed. It would sound similar if it has an issue with low fuel or excess air.
P.S. It seems that you are almost home. How are you feeling about your decisions at this point in your venture?

 

We're getting close to fixing the issue here guys.

Some things to consider....

1) The intake manifold and throttle body are from my old engine. I had a similar (if not the same) problem when it died before...

2) When it wasn't starting before I thought gas was the culprit and I drained the tank by jumping the fuel pump relay. So I think the fuel pump is good.

3) I put my hand over the butterfly valve to limit air flow and it held an idle for much longer especially when I found the sweet spot.

4) My O2 sensor is also from my old engine bit I don't know if it could cause a problem this bad.

5) I also have no catalytic converter, muffler or tailpipe for the Jeep right now but I think it should be able to run without those right?

So I'm thinking about going back to the junkyard to pick up a better/alternate TB.


Jeeps run better on A&W

Here is another clip with the can in place.