258 dies under load

[somdfisher]

I have been searching google and jeep sites for 3 days now, and I can not for the life of me find anything that matches my problem. Either they have the same problem with a different carb, or same carb but a slight difference in problems.

I recently had my timing done. Before it was sitting around 41* and is now at 9*. Idles great, choke working good after some wiring debacles. The other night I started the Jeep and since I seemed to have solved my oil pressure problem for now, I wanted to drive it. After letting it idle and warmed up, I hopped in, threw it in reverse started to let the clutch out and it died. Started right back up and I revved it a little higher and let the clutch out and it moved a little, sputtered and died. I was able to move it back into its parking spot by revving it high and half riding the clutch.

Before the timing was set, it idled really high, blew out a black watery liquid (unburnt fuel) and since then that has all stopped. It's set to idle at 800. I was able to drive it before the timing was set but it sounded like it was running at like 7000 rpm to go 35 in 3rd. I have replaced all fuel lines to correct size, new fuel filter, air filter, and sending unit.

The Jeep has the AMC 258 i6 / 4.2l with Carter BBD carb without the electrical stepper motor or sol-vac idle solenoid. Only thing I see is the mixture screws.

Please help.

 

[ken98k]

Plugged catalytic converter?
I had a ford pick-up tahst had the symptom you described, turn out to be a plugged converter.

 

[Tommy]

We need a lot more information to get a good picture of what's going on. You said you recently had the timing done and it was changed from 41 degrees btdc to 9 degrees btdc. Did it run at 41 degrees? That would be a problem in itself. Always look for the simple fixes first and expand from there. When you change something and it stops running right, whatever you changed is usually the problem. You could have a vacuum leak, bound drive train ( E brake on) or any number of things going on. Hopefully the black watery substance coming out of your tailpipe is just condensation mixed with black soot in your tailpipe. If it's unburnt fuel I would be scared. I would check that your wheels are turning freely to start with. Jack them up one at a time and turn them. I would check the vacuum lines and make sure your carb is tight on the manifold. Start the process and let us know what's going on. It's hard to diagnose a problem on the internet but the more information you can give the better the advice will be coming back.

Tommy

 

[somdfisher]

It was running at very high idle when it was timed high. I could smell unburnt fuel while it was timed that high and it seemed to be missing. It was that mixing with soot in the exhaust. I have done a 2 year rebuild of the Jeep, cleaned all axles, replaced brakes, all brake lines including parking brake. I have driven it in the past 2 weeks, but not since we timed it. The choke didn't work so I had to fix that. I did not rebuild the engine just axles, frame, and body work to make it safe to drive.

The carb would back fire from time to time, but I have gotten that to stop by adjusting the mixture screws. I am thinking the mixture is still off a little bit, but I don't know much about the carb, and everything I have read is for a newer feedback one. There were a lot of unhooked hoses in the engine bay when I got it and ran through diagrams upon diagrams to replace and repair all the leaks there could have been and was when I bought it. I can hit the pedal or give it gas at the linkage and it rev up fine but its when I put it in gear and put the motor under load does it want to stall.

 

[ken98k]

I can hit the pedal or give it gas at the linkage and it rev up fine but its when I put it in gear and put the motor under load does it want to stall.

Did you check for plugged exhaust components?
Does it have a cat. converter?
Your symptoms are exactly what I experienced with the Ford I mentioned earlier.

 

[somdfisher]

No, didn't get a chance to yet. I do have a cat and planned on removing it and replacing the while exhaust down the line, but I will have to look into it sooner.

 

[1986cj7]

We need a lot more information to get a good picture of what's going on. You said you recently had the timing done and it was changed from 41 degrees btdc to 9 degrees btdc. Did it run at 41 degrees? That would be a problem in itself. Always look for the simple fixes first and expand from there. When you change something and it stops running right, whatever you changed is usually the problem. You could have a vacuum leak, bound drive train ( E brake on) or any number of things going on. Hopefully the black watery substance coming out of your tailpipe is just condensation mixed with black soot in your tailpipe. If it's unburnt fuel I would be scared. I would check that your wheels are turning freely to start with. Jack them up one at a time and turn them. I would check the vacuum lines and make sure your carb is tight on the manifold. Start the process and let us know what's going on. It's hard to diagnose a problem on the internet but the more information you can give the better the advice will be coming back.

Tommy

With your timing being out so far the timing chain may have jumped a tooth not sure if being at 41 and going to 9 is a big enough gap to think of a tooth jumped on the timing. But it would be some thing to think about. Hopefull someone with more knowelge will chime in. This black liquid comeing out of the exhast pipe did it smell like gas I'm assumeing it did or you wouldn't know it was gas. But if it was pouring that much gas though the carb I would think it would flood out and not even run. And how long did it sit I know some times condencation can build up and be shot out the exhaust as a black liquid. Like said before more info would help.

 

[JR74CJ5]

I think Ken may be on to something, but I would do Tommy's recommendation first.

I know you rebuilt the stuff not long ago, and I know it should not be a dragging parking brake etc, but i have seen 2 other posts lately where the jeep would run great and die under load. they were both the parking brake stuck.

Jack it up and check wheels moving freely. It's very early, and will eliminate the possibility.

The plugged up exhaust is most likely the culprit though, as you had so much gunk going through it... But i know no way of testing that without the old, buy and pray it works...

Here's a link of the latest one I spoke of... : http://www.jeep-cj.com/forums/f2/cj5-clutch-issue-11432/

~ JR

 

[somdfisher]

The gas smell is gone. Very high idle and timing off was the cause. It was idling at 1700 warm. After correcting timing it was still at 1400.

 

[CJim7]

I cant even imagine it running at 41 degrees advance timing

 

[CJ]

Sure sounds to me like a tooth is off on the gear set or even on the dist.

 

[somdfisher]

I wish I could explain better the timing thing better. My buddy who is a mechanic and runs is own business stopped by the house and timed it. Never took it for a test drive afterwards. His timing light measures the RPM's as well. If I could explain it better I would. I am not used to working on carbed engines so I am in a learning process. Depending on the rain that is going on right now, I may just cut the cat out, planned on loosing it anyways, and put a straight pipe in its place and see were that gets me.

 

[ken98k]

Most of these guys known a lot more about this stuff than I ever will, so I'm just offering some personal experiences.
I had a timing problem with my 304 last summer but it behaved somewhat differently than you're describing. It seemed as if it was "underwater" when I tried to accelerate.

Speaking of underwater, I once had a boat with a Turbojet motor.
Part of the exhaust system was a “u” shaped rubber hose.
The hose became damaged internally and would develop a bubble between layers of the rubber when I tried to accelerate thus blocking the exhaust, but at Idle it worked fine.

 

[Tommy]

I am having a hard time believing it's the catalytic converter. It seems to me that if you can rev the engine and it idles fine in neutral the exhaust system should be alright. A plugged cat would bog it down whether it was under a load or not. Rather than cut it out, try unhooking the exhaust pipe at the donut gasket where it attaches to the head pipe and run it like that. That would be a cheaper and easier way of testing the cat theory. You may just need a tune up. New plugs, distributor cap and rotor along with plug wires if it needs it can make a lot of difference. Double and triple check your vacuum lines and make sure the carb is not loose. Timing issues are timing issues and it shouldn't matter whether you have fuel injection or a carburetor. I know you rebuilt the axles etc., but as mentioned earlier, make sure your wheels are spinning freely. If the problem only happens under load, you need to eliminate that possibility. Overall though, jumping a tooth on the timing chain or an overly slack chain would explain all the problems you are having. A compression check would show you this real quick. Compression would be off on all cylinders because the valves would not be in sync with the pistons. If it's a slack chain you will hear it rattling around in the cover while it's running. There are a lot of tests you can do without spending money.

Tommy

 

[1986cj7]

How do you know the timing was at 41 I've timed mine severel times and I dont even think you would even see the timing line on the crank pulley. On mine I can only see to about 28 dregees on the scale. I'm not questioning your info just woundering how you found out it was at 41 dregees?

 

[somdfisher]

My buddy has a timing gun that has a load of settings in it. When it was on a lower setting he couldn't see the line on the crank until he got up to around 41*. We set his gun to 9* and timed it to that. After we got it timed, we still had to bring the idle down. I plan on removing the cat anyway so it doesn't both me to do that. I understand timing is the same for fuel injected or carburated engine, I don't know the exacts about setting up a carb. I have new plugs, wires, and distributor. I noticed the exhaust was smoking last time I drove it around the cat, and I figure that was from the oil that got on it while I was fighting an oil leak.

I have never timed an engine before so, I am without the exact information. I watched and helped my buddy do it so I have the understanding now. I am going to rent a timing light from autozone or advance auto tomorrow to recheck timing. All I can say is before we timed it, it was running rich. I had a white step stool sitting behind the Jeep that the entire side is black now (and so is the front tag on my commuter car). After timing I turned the stool around to a fresh side, and let it run on the stool for about half hour. It was still white afterwards, and a little melted, so we fixed something.

 

[somdfisher]

I got it working for now. I advanced the timing a little bit and it flattened out. I took it for a spin and it has power now, and spun my 33" tire a little bit on a hill. I am going to get my own basic timing light and see where it is and get the timing perfect.

Thanks for the replys