CJ-7 engine questions

[Harpflo]

Hi guys,

Im new to this forum, but figured I would go ahead and ask some good questions about my jeep because I don't really know where to begin.

Brief history about the jeep: 1980 CJ-7 with lift and 33's. Engine is an AMC 360 V8 out of an old jeep wagoner. I bought this jeep 2 years ago when I lived in Wyoming, from my neighbor at the time. He bought it from a guy who had planned to restore it as a father/son project.

Anyways, since Ive had it I have replaced the clutch and had some transmission work done. I moved down to Pensacola, florida in early September. Right before I moved, it started doing something weird while driving. Anytime I would hit a big bump, the engine would die. It would always start right back up though. So fast forward a few months. I transported it all the way down to florida from Wyoming on a trailer. Ended up getting to florida, and the damn thing would not start at all. I ended up wearing the battery down and took it to AAMCO. The guy said that to him, the engine wasn't running right. But that he would try just replacing the starter cable, battery, ignition cables, and spark plugs first, before pursuing it further. Well, it has been running great. Until today!

I barely made it back home. Here is what its doing. It started up, but died several times. Finally started up and I drove it 4-5 miles. Once I got up to 35-40 mph, it started to die. Or if I hit a big bump, it would die as well. It also did the "uncle buck" backfire numerous times. Needless to say, finally made it home and parked it. Now its not even starting. I will probably try it again in a few days.

I just wanted to see what yall thought. Does it sound like a possible carburetor? Or something with my ignition and timing? With my jeep Cherokee, I always try to do as much maintenance on it myself as I can. With my cj, I just don't really know what Im doing. The inline 6 seems so much easier to work on than this engine haha. I don't have a lot of time to work on it myself because Im so busy with work. So I may take it back into AAMCO and see what they think. Wanted to get some opinions first.

 

[SteelHeadz]

First things first.. Check for fuel and ignition. I have reason to believe that this issue might be likely caused by an electrical issue. Check the main battery feed to the ignition switch, fuse block and the connections behind it. A wiggle test might help while the engine is running.

 

[Harpflo]

Appreciate the advice for sure. I have Wednesday afternoon off, so I will try to take a look at everything then. To me, with the backfiring and loss of power and engine sputtering, doesn't that point to a possible carburetor issue? But I will definitely do the wiggle test.

 

[superj]

No, not a carb problem. Carb problems dont come and go. It happening on bumps leads to believe that its a wire loose, shorting to ground, or arcing to another wire.

Check the distributor cap and make sure the contact inside is good and not broken or stuck when you push it

 

[69jeepcj]

I tend to agree with steelheadz. The engine stalling out sounds like a loose connection, or short somewhere. Just to add to his suggestions, check the wires in the engine compartment that go through the fire wall to the fuse box, wiggle them with engine running. My dad's had a short right there and when he hit a good bump it would kill the engine, but would start right back up. The backfire and bucking sounds like timing or ignition problem though to me.

 

[Harpflo]

Thanks for the suggestions guys. I will keep yall updated.

 

[hoobness]

Ignition, power to it like the others say

 

[Harpflo]

Well heres an update. Was able to get it started this afternoon. Engine quickly died. Started it up again and revved the engine a few times and it eventually started to sputter. The RPMs were going haywire. Its started again and stayed running for about 15 minutes. I jiggled everything in there and could not get a response. Got back in it and the engine died again. Started it one more time and was able to drive it long enough to park it in the street (in case I need to get it towed), then the engine started sputtering again. I revved it up to 3500-4000 RPMS, then it started sputtering, shooting between 0 and 2000 rpms. And now there is definitely something rattling with my exhaust system. Pretty sure it had to do with the other day when it was backfiring on the interstate. I could literally see cars beside me swerving because it was backfiring so loud haha. Any further suggestions would be welcome. Looks like I will be taking it in soon to get it checked up.

 

[hoobness]

..."Started it one more time and was able to drive it long enough to park it in the street (in case I need to get it towed)"

Lol best string of words I've read in a while. Sorry I don't have much to contribute.

Really man id check the ignition harness, the distributor and or just replace it all. Out the door can't be more than 150 for OEM and piece of mind.
With old cars(that's all I ever own) I just replace stuff when it becomes a mystery aka hassle. For example with my 78 cj, I couldve tracked and troubleshooted a brake light issue and not had 110% peace of mind or just pull out all the wires and rewire the circuit and replace all the lights and switch for a negligible $ and mostly just time. I chose the latter. My 77 merc 300d has a vacuum issue. Instead of replacing 20' of line just so the doors are full auto I just closed that circuit under the hood and went on with my life... the older i get the more valuable time becomes.

 

[69jeepcj]

I reread your first post, and you say the guy at AAMCO replaced some things along with the sparkplugs and it ran great for a while, and starting doing it again. Sounds to me like your plugs may be fouling out, I would look into timing or a carb issue. Other than the plugs the guy only replaced wires and it ran great for a while, (until the plugs fouled). Can you check your timing yourself, or adjust a carb? timing chain may have something to do with this too.

 

[Harpflo]

Haha, I hope I don't have to tow it. The sparkplugs were replaced about 2 months ago. But it was having this issue off and on before I had them changed. Aamco basically just replaced the battery, ignition cables, plugs, and the starter cable. I can check the timing myself. The carb I can adjust. Its tough for me to even try to work on it because Im usually working all day. Plus I live in an apartment complex where the landlord is a stickler about doing auto maintenance there. I really just don't have the time, that's why Im going to let somebody else just mess with it. I really just want to get it running again so I can try to sell it. I just don't have the time or money right now to make it worthwhile to me. Plus, somebody else can get and do a great job on it. Thanks for all the suggestions guys.

 

[Harpflo]

"I can check the timing myself"

I meant to say that I CANT check the timing myself. That's why I would rather somebody else check who knows more than I do.

 

[carnuck]

Here's the first thing to do:
Fuel filter. Add a see-thru one in the rubber hose right before the fuel pump too. Crud from the tank can jam the inlet vale open and drop the fuel delivery. Make sure the oil isn't full of gas!
Then, get it running and bang the ignition box with a rubber mallet (or tap with a small block of wood). If it stalls, you found the problem. It's a common Ford box. Oh! And make sure you have a ground wire from the battery negative to the body as well as the motor. The ignition box requires an excellent ground to operate properly. Next step is the ignition coil. If it has the stupid plastic horseshoe connector that is 90% of the time corroded, I would get a coil for a '70s Mopar (Napa part number IC12 or the cheaper version IC12SB) and cut the connector off and wire straight to the terminals.
After that would be the pickup coil in the distributor (or mechanical advance fell apart with tons of metal bits under the cap). Temporarily unplug the field wire on the alternator (if it has a short, it may be making AC power which will mess with the ignition) The backfiring may have blown the powervalve in the carb. You can get the expensive "correct" rebuild kit for the carb, but if it's a Motorcraft 2100 (no hose on the powervalve cover under the bottom of the front of the carb) you can get a kit for a '72 Ford pickup with 390 and 2 bl carb. It has a single stage power valve so it's a little better on fuel than the dual stage (that I've found)
You can do only the powervalve but you have to take the carb off to do it. Making sure the mating surfaces of the carb and intake are clean and the gasket covers everything it should is important. If yours has the insert gasket, you can order that by itself.
If none of this works, then the bad news is you probably have a walking camshaft, but that's been fairly uncommon on stock cams with AMCs.