I'd imagine that you have all those sneaky hoses for vacuum this and vacuum that and it really could be one of them misbehaving. Just for the heck of it, check your fuel filter. You should have two of them on that rig, one before the pump and one after the pump that splits and sends fuel to the carb and the other back to the tank.... Make sure that both are clear. Easy test is to blow into the inlet side and make sure that air will pass through them with little effort. On the one with two outlets, check for both sides. If you are running too rich, could be because your return line is clogged and too much fuel is getting forced into the carb. As for the starting up okay, idle okay, then when you try to run it and it starts running rough, this is a prime reason for that to happen. There is enough fuel getting by to idle okay, then when you need more gas, it doesn't get it. I was reading an article yesterday about another problem, the idle ports inside this carb get clogged sometimes, and dribble fuel at the wrong time into the throat of the carb. I can look that up if you want to persue that. I'm still leaning to the vacuum issue, that can be a result of so many hoses or the components that they go to.... Never really know without being there though.

Along with a wrong mix, you may also be experiencing a timing problem. Check or get checked your timing, Your chain, how old is it? Have you ever had the distrib. out? If your timing is off, you may need minor adjustments or may need a new timing chain....

The brown color is OK for that engine..
Good to see more information. Plugs changed out just ain't gonna cut it for a tune up.
From this easy chair here, first guess is a coil! 2ed guess is the sparkbox.. Gasoline does not enter into my calculations. I suspect the fuel system is Ok at worst. Popping and cracking usually occurs from spark coming and going. So I would go for a new coil and sparkbox...today!
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

Then I would take that electric pump off of there.

You can check Videttes guess easily by pouring an ounce of gasoline directly into the carb top! If that don't get it to running it is NOT a gasoline failure.
Go get a coil and a sparkbox.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

Thanks once again for all the good feedback. Bought the jeep used 4 years ago. Never really done much work on it, until lately. Talked to my dad tonight...Great minds think alike. He also mentioned looking into the distributor. I have not checked the timing yet. Been busy trying to find the leak. May have found one. The PCV breather and PCV valve are oily. This may have caused the Decel Valve to stick open. Read about this on the web. This would create a big manifold vacuum leak. Anyway, going to the dealer to get one. Also, going down to my friendly NAPA store to get a dist and coil.
Is there an easy way to find out if the timing belt is bad? How difficult is it to change? Engine removal? Tomorrow I will check the timing.
Oh...by the way...I have 3 fuel filters. A clear one before the rear electric fuel pump, another clear filter after the mechanical pump and before the stock filter. All look very clean. Just changed them after my last trip.
Something has been bugging me for sometime now about the mechanical fuel pump. Last summer, I had vapor lock (??). Before that trip I had remembered that the fuel would fill the clear filter completely. After that summer trip I started to notice that the clear filter would not fill up with fuel. Instead you could see the fuel being "pumped" in the clear filter. Just recently, it seemed to only fill half up with fuel. Today I replaced the 8 month old mech fuel pump. Guess what...The clear fuel filter is once agian full with fuel.. One problem solved..

Until tomorrow.....Good-night

One more comment. I was reading on the web about the stepper motor / metering pin function. I did a test as stated on the web. Anyway...while the engine is running the metering pins do not move. The article says that they should move back and forth. My metering pins are fully forward and not moving (rich position) while idling. The next test I did was to rev up the engine and close the choke plate until the engine gagged. This forced a rich condition and sure enough the metering pins moved backward. The article states that I should be looking at 1) non functioing O2 sensor, or an air leak or vacuum leak.

We're getting somewhere, this is good. Mechanical fuel pumps have a diaphram in them that goes bad over time. Not having a good filter before this pump has caused countless pumps to fail. WalMart has a good enough filter for this application. I was just looking at it yesterday, costs next to nothing and comes with hose clamps and some extra hose for someone that is installing it on a stretch of metal fuel line.

How strange, they also have the PVC valves and a couple of the breather things. They are made by Fram, and are okay. So no need to go to the dealer unless you want to look at the new Jeeps.

Read up on the distributor swap before doing it. If you aren't careful, you really could make a mess out of this! Be careful! It isn't that hard to do, but you have to do some marking and inspections.... The coil, that's an easy one... Just make sure you hook your wires back up the same way. I believe that yours has a harness style mount, makes it easier.

Timing chain replacement.... It isn't TOO hard, but is a bit of a knucklebuster if you don't have the right tools. You will take off your fan belt, fan, alternator, AC unit if equipped.... and just lay them off to the side. Then you can get to the timing cover. You'll free up some extra work space if you pull the radiator, but isn't necessary, but be careful not to bang into it or the hoses. That top hose's mount has given several of my friends a headache because of leaks that were due to leaning on that hose while working on something... then the green puddles started appearing....
Anyway. You really should get a chilton repair manual. I've got one that I will be listing on eBay some time today. It's just an extra copy I just bought because I couldn't find my old one. Like the old one better and just found it the day before yesterday. They aren't as expencive as they used to be and have all the instructions you could ever imagine in them.

Remember, most NAPA stores give a discount to AAA members. I find that the littler ones or the ones out of the bigger cities... they say "we're not set up for that yet".....

Naturally!

Dude you are not LISTENING! If an engine will not start the first thing to do is to pour an ounce of gasoline directly into the top of the carb! If it does not start with that then you KNOW FOR SURE your problem is electric!!
If you have not changed out the coil and the sparkbox yet DO IT FIRST!! Leave the dist to last, it is not a cakewalk to change out for most folks. The problem with those clear filters is they allow you to SEE the air bubble in them, this has caused worries in lots of unknowning folks over the years. Do not give it a thought! That bubble is inside of ALL of that type of filter! It is caused by gravity, a liquid seeks it's own level and inside of the filter level does not always fill the thing with gasoline..no problem with it however.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

Dude you are not LISTENING! I just stated in my comment yesterday that the engine WILL start. "...while the engine is running the metering pins do not move...." The engine STARTS just fine!! What I have been saying is that the engine misses, backfire. Sometimes it idles smooth then will begin to idle rough to a point of dying. I can step on the gas a little and the engine will smooth out.
Talked to a local shop today. I described the symptoms. He mentioned could be a worn timing chain. Worn timing chain will cause missing, backfiring. The timing is OK. It would also create an internal vacuum leak. Anyway, the jeep has over 154,000 miles on it. I bought it used so I do not know how old the timimg chain is. He also suggested putting a vacuum gage on manifold vacuum. Did this today. The vacuum at IDLE (engine running) is about 19-20 Hg. The gage does not move. From what I have read, this is normal vacuum range (16-22Hg).
I have decided to change the timing chain. My buddy has done several on his CJ-5 and Commando.
By the way...I am NOT worried about air bubbles in the clear fuel filter!!!! I was just stating an observation and found the fix. I like the clear ones so I can see how much dirt is getting thru. I buy all my filters from Walmart. I already have a Chilton and Haynes manual. Thanks anyway. Mine is very greasy...I used it but also like to get other people comments/feedback. This is the way I learn by using others experiences.
More tomorrow...