A rhetorical question/guessing game.

[IOPort51]

Drove the CJ today, temp about 45 deg., drove it last on Saturday, new high test gas on Saturday too.

Started OK, running a bit cold natured, nothing new there but kept getting worse. Idled OK just no acceleration under a load. about half way to work could barely keep it lit. Pulled over and shut it down to look for loose vacuum hose, stuck choke, bad ground, whatever, found nothing.

start is up and it runs like a top, as is normal, the rest of the way in.

I have no clue what the problem was, any guesses?

 

[Munypit]

Thats pretty much how my problem started. i guess it has the flu, about to pull my hair out trying to find the problem.

 

[Munypit]

IO, I have been trying to research this problem on this board and a few others trying to find a common denominator. i have found 3 threads with almost the exact same symptoms, Engine will crank and idle fine put put it under load and lose power (like it is starving for fuel) All 3 threads have different carbs Mine is a carter bbd, yours 2100 and another with a webber. So that should throw the carb out of the picture. My problem has gotten progressivly worse to the point of letting her idle in my shop, feeling confident enough to take off on the highway only to go dead in almost the exact same section of road. I've replaced fuel pump, and filter. chased wires to the moon and back and replaced the ICM. I'm going to pull the tank this evening and see if something is going on there.

 

[Torxhead]

IO, possible stuck needle valve? Try it again later. Determine if it is a lean mixture or rich. Also if the choke is a factor and if it is sticking. I would hate to hear it is ignition related, especially with that MSD box.
Munypit, have you considered having bad fuel lines from the tank to the fuel pump? A fuel pressure check could reveal something.

 

[IOPort51]

It was fine this afternoon coming home. I was thinking maybe the choke got hung up, the accelerator pump had an air bubble or the vacuum advance was stuck. just now thought of it but it backfired a couple times like it had a vacuum leak, just can't find one.

Moneypit, check the timing and see if it is advancing when you rev the engine.

 

[Saddle Tramp]

I would check the fuel pump. If a stock style pump when they start to go out the pump can run good then not run good or even let the motor die but if you sit on the side of the road for a few minutes all will be good for a while anyway.

 

[Barry2]

When mine did that it was the primary fuel filter clogged up with sediment. Just another thought for you.

 

[Hedgehog]

Lets start simple. How cold has it been where you are? Has the weather cycled warm/ cold/warm /cold? Do you keep your tank full or do you let it run down before refilling? Could be water condensation in the tank. Dump some dry gas in the tank .... do they still make such a product? Dry gas was a common thing in my northern New York youth. Car sputters, in goes the dry gas and things are right with the world again. There must be some sort of dewatering stuff still available. In Arizona this water is not generally a problem.

 

[Torxhead]

Lets start simple. How cold has it been where you are? Has the weather cycled warm/ cold/warm /cold? Do you keep your tank full or do you let it run down before refilling? Could be water condensation in the tank. Dump some dry gas in the tank .... do they still make such a product? Dry gas was a common thing in my northern New York youth. Car sputters, in goes the dry gas and things are right with the world again. There must be some sort of dewatering stuff still available. In Arizona this water is not generally a problem.

I remember that stuff, I got some once at a gas station. I had previously filled up at a location out in the boonies where apparently water had got into the gas station's tanks. I saw some water thru one of those see thru gas filters. Jeep ran like before and this stuff made my ride home a lot easier.

 

[PaRenegade]

Maybe you simply got her up too early and she was still wantin' to sleep!

 

[Neuner]

It was fine this afternoon coming home. I was thinking maybe the choke got hung up,

I've had the choke do that to me. After I played around with the choke adjustment to try and resolve the problem, I wound up putting it back at the previous setting. Never had the problem again. Was figuring I maybe tightened it incorrectly the previous time but didn't see the impact of it until the cold weather hit.

 

[51 CJ3]

A lot of good ideas here. My first thought went toward the fuel filter but after thinking on it a bit another possibility came to mind. I have seen trash in the tank plug an outlet then moving/floating away after shutdown. That could make for a very random occurrence.

 

[Munypit]

I found a sticking PCV valve with my problem.