Orange sparks from exhaust manifold????

[Junky CJ]

Alright, so I'm Jeep newbie looking for some help. I just bought this CJ5 with the AMC 258 i6 / 4.2l and it had issues from the very beginning where it would stall out on the road. Symptoms were similar to vapor lock in that it would start to stall at no particular time, losing power and jerking forward, feeling like the fuel was cutting out or was maybe too rich, sometimes it would backfire.

After adjusting the carburetor, putting in a new fuel filter, hunting for vacuum leaks, and removing the manifolds to look closer for any holes or anything of note, we decided we would replace the timing chain the next day. Now at the time when we ran it no sparks appeared. Still would backfire mostly at high RPM.

We replaced the timing chain today, the old one was very loose and after we drove it briefly, it seems to run smoother, but backfiring still occurs and now orange sparks are appearing from somewhere under the manifolds when we rev it.

It is important to note there are small exhaust leaks on the manifold the previous owner seems to have welded over, but not completely sealed. There is also no catalytic converter, but the sparks are appearing in the engine bay beneath the manifolds, not in the exhaust pipe. We've tried adjusting the carburetor but it doesn't seem to help. We already tried putting oil in it and seeing if the oil is flowing under the oil cap, so it appears to be fuel getting into the exhaust manifold. Has anyone ever dealt with this before? Should I be looking at the fuel and air system or did we do the timing chain incorrectly? Could the distributor be messing up the engine timing still and causing this issue?

Basically, now that you've heard the story of my 1,800 dollar basket case CJ, can you tell me what to look for and check on?

 

[Peanut Butter]

Alright, so I'm Jeep newbie looking for some help. I just bought this CJ5 with the AMC 258 i6 / 4.2l and it had issues from the very beginning where it would stall out on the road. Symptoms were similar to vapor lock in that it would start to stall at no particular time, losing power and jerking forward, feeling like the fuel was cutting out or was maybe too rich, sometimes it would backfire.

Vapor lock is usually eliminated by using a return fuel line. You should have a fuel filter on top of the engine that looks like the one in the picture below. It could also seem like vapor lock, but be the timing chain. You didn't say if this went away after replacing the timing chain.

After adjusting the carburetor, putting in a new fuel filter, hunting for vacuum leaks, and removing the manifolds to look closer for any holes or anything of note, we decided we would replace the timing chain the next day. Now at the time when we ran it no sparks appeared. Still would backfire mostly at high RPM.

Did you check the timing with a timing light after replacing the timing chain. Sometimes people feel like they have the engine at top dead center when they replace the distributer, in reality they are 180 degrees off. Timing light will help with this.

It is important to note there are small exhaust leaks on the manifold the previous owner seems to have welded over, but not completely sealed. There is also no catalytic converter, but the sparks are appearing in the engine bay beneath the manifolds, not in the exhaust pipe. We've tried adjusting the carburetor but it doesn't seem to help. We already tried putting oil in it and seeing if the oil is flowing under the oil cap, so it appears to be fuel getting into the exhaust manifold. Has anyone ever dealt with this before? Should I be looking at the fuel and air system or did we do the timing chain incorrectly? Could the distributor be messing up the engine timing still and causing this issue

The exhaust manifold is made of cast iron. Cast iron is difficult to weld. There is a special procedure that requires heating the item before apply the weld and cooling slowly afterwards. Doubt this was done. Start looing for a used manifold to replace the one you have. You don't need the catalytic converter, unless it is required by your state law or for inspection. Some older cars are exempt due to age on these things. At this point, it's not an issue.

You talk about putting oil in it. Not sure what you mean here. All engines require oil, adding too much oil could cause problems.

Do you have a proper PVC valve? Is it functioning properly?

Again timing is everything. Unburned fuel can be caused by timing or by running the carburetor to rich. Check timing first, then adjust the carburetor.

Do you have a true Jeep Full Service Manual? If not get one, it will help you with adjustments.

Did you reuse the gaskets when you removed the manifolds? You need new gaskets when you do this, then torque to speck.

If none of this helps, may be time to get a professional involved.

 

[Dphillip]

Sparks? Where do the Sparks originate from? Is there a loose ground cable attached to the exhaust manifolds? I associate sparks to a electrical issue.

 

[Torxhead]

I would suggest looking at the spark plug burn deposits to check for fuel richness. Along with getting that what sounds like a leaky exhaust manifold fixed. Look at that money you spent as potential for having lots of fun but it does come at a price.

 

[Junky CJ]

We didn't use a timing light. We resealed the timing cover with RTV and brand new gaskets. I mentioned it has oil flowing through the motor because I was told check it, in case I was melting the pistons or something extreme like that. Didn't think so, checked anyways.

PCV valve is the little metal valve that goes in the top of the engine? Replaced it already.my guess is timing or improper carburetor adjustment.

Where can I get a true Jeep service manual? All I have to go off of is a super generalized Haynes manual.

 

[Peanut Butter]

I got my service manual from eBay. Here is a link: 1972 JEEP SERVICE MANUAL | eBay


There are other places to find one, this was the easiest for me. I understand the oil now. I don't think your doing anything to the pistons.

First I would correct the manifold issue. You should be able to find a used one. Try local junk yards. Don't need to look just at Jeeps. Several AMC vehicles came with the AMC 258 i6 / 4.2l I6 engine. Get new manifold gaskets too. These can come form your local parts store. And the proper fuel filter (see picture). Once the manifold is in place, test it again. If the same problems exists, find a timing light and set the correct timing. I think this is the biggest problem aside from the manifold. Timing lights are hard to come by, but somebody you know may have one, or check with a mechanic that repairs older cars.

Here is a general article about some things you should do when you first get a Jeep: https://www.jeep-cj.com/forums/f99/what-do-after-getting-cj-home-10146/

Pictures will also help us diagnose some of your problems, so don't forget to add them to future posts. Try to do those three things first and then let us know what else is going on. We'll see what we can do to help.

 

[Lumpy Grits]

X2 on checking for electrical contact issues as the possible cause of the sparks.

This could also be unburned fuel from your timing being so far off.
Get a timing light, and set the ign timing to specs.............

LG

 

[Junky CJ]

Thank you for your help, everyone. Especially Peanut butter.

The next time I work on the CJ, I'll take some pictures. Until then I'll look for a new exhaust manifold, get a hold of a timing light, and make sure I don't have any bare wires floating around the engine bay.