Help, I'm stumped - JeepForum.com
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post #1 of 33 Old 06-08-2017, 03:49 PM Thread Starter
wsmutch
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1986 CJ7 
 
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Help, I'm stumped

I have a 1986 CJ7. It has a 1972 258 IL6 with a fairly new MC2100 carb. It has been neutered, and I have done the ford distributor conversion. I keep the Jeep at my hunting camp way up north so I have to do most of the maintenance myself. Here is whats happening. It will start, warm up, and run great for about an eighth of a mile then it starts to balk. I have to rev it to keep it going and it is all I can do to get it back to camp. If I put in the clutch without reving it it stalls. I replaced the coil, plugs, distributor cap, rotor, both fuel filters (It is getting gas even after stalling) I adjusted the timing, adjusted the carb. I check for vacuum leaks. I'm stumped. I hate to have to borrow a trailer and haul it to town. Any suggestions would be great.

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post #2 of 33 Old 06-08-2017, 06:31 PM
skizriz
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Quote:
Originally Posted by wsmutch View Post
I have a 1986 CJ7. It has a 1972 258 IL6 with a fairly new MC2100 carb. It has been neutered, and I have done the ford distributor conversion. I keep the Jeep at my hunting camp way up north so I have to do most of the maintenance myself. Here is whats happening. It will start, warm up, and run great for about an eighth of a mile then it starts to balk. I have to rev it to keep it going and it is all I can do to get it back to camp. If I put in the clutch without reving it it stalls. I replaced the coil, plugs, distributor cap, rotor, both fuel filters (It is getting gas even after stalling) I adjusted the timing, adjusted the carb. I check for vacuum leaks. I'm stumped. I hate to have to borrow a trailer and haul it to town. Any suggestions would be great.
Does it belch black smoke when it starts acting up? Sounds like the choke isn't opening up.
Remove the air filter and look down into the carb, the choke flap should be closed when the engine is cold.
Now start the engine and allow it to sit and run. As the engine temp rises, the choke flap should slowly open over the course of 3-4 minutes.
May have to blip the throttle a time or two while it's opening.
The choke flap should go from fully closed, to fully open. If it doesn't open, a warm engine will run very rich, crappy, and blow black smoke.

Do that and see what happens.
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post #3 of 33 Old 06-08-2017, 06:47 PM Thread Starter
wsmutch
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Thanks for responding, I have a manual choke and it is wide open.
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post #4 of 33 Old 06-08-2017, 09:55 PM
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Ignition module???

Ed
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post #5 of 33 Old 06-08-2017, 10:07 PM
258
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^^^ second on the IM. Classic symptoms! Usually when it get too hot.
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post #6 of 33 Old 06-09-2017, 08:36 AM
pedal2themetai
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carb flooding?
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post #7 of 33 Old 06-10-2017, 06:47 AM Thread Starter
wsmutch
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I'm going to look into the ignition modual. What is the best IM? Here is one other thing I forgot to mention. I started it with the hood open to check the choke. It started but wouldn't stay running unless I kept reving it and stalled. I turned off the key and it still gave one last turn of the starter. The key was in the ignition but was in the off position. It happened at least one other time while I was working on it but not every time I shut off the ignition.
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post #8 of 33 Old 06-10-2017, 07:03 AM
tripmaker
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Trash or water in the gas tank. Or fuel line closing up. Good luck
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post #9 of 33 Old 06-10-2017, 07:58 AM
azzkicker
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It sounds like you're saying blipping the throttle keeps it running, which makes me think the accelerator pump is the only thing putting fuel into the engine when you're having this problem. If that's true then every time you go off the throttle and back on, you get a shot of gas, but otherwise it's starving for fuel. If that's what's happening, then you have fuel in the float bowl but it isn't getting to the engine without the help of your accelerator pump. If true, that means you have a clogged low speed circuit (I don't know your carb, but most have a low speed jet).

Many carbs have a cold or choke circuit that adds fuel to the (maybe clogged) low speed circuit, so that might be what's making it run right until it warms up.

If hitting the throttle makes it run, it can't be an ignition problem (your ignition system has no idea where your throttle foot is). If more throttle runs better than less throttle, it can't be a fuel tank, filter, pump, or fuel line collapsing problem, since all of those are worse the more throttle you use.

If you leave this vehicle sitting on a regular basis, you will gum up your carb much more often than a daily driver. You might consider using fuel stabilizer, or go really nuts and put in a fuel line cutoff so you can run it out of gas every time you're about to leave camp (an electric solenoid with a hidden switch makes a great anti-theft device because they will think it just won't start). That won't help the gas in the tank, but it should reduce the carb cleanings. An old straight six is pretty good at burning crappy fuel, in fact my tight wad dad used to take any old gas that he thought was bad (like from a motorcycle that won't start) and pour it in his 76 CJ with a 258. I thought it was dumb, but it never bit him.

I would tear into the carb and clean the hell out of it. It won't hurt.
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post #10 of 33 Old 06-10-2017, 08:34 AM
Nucking1Futs
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The basics, FUEL-AIR-SPARK.
I am leaning towards Ignition module, carb issue would be second guess. More engine configuration would be nice. Pics and videos are awesome too. With that.....
Have you open up the carb and cleaned it? Through a rebuild kit in it anyways, adjust float, clean clean clean! Make sure venturis are not clogged. DO NOT USE A RAG THAT LEAVES LINT (I have experience with that and the Carter electric feedback BBD)! What color is the fuel? (if brown, drop tank, clean it, replace sock on pick up).Have you replaced the fuel filter?

What color are the plugs? Are they fouling? Timing? Vacuum advance working? Dizzy working properly? Have you check the connections between your dizzy and IM? Do you have a ballast resistor or resistance wire to your coil? You have to have one or you will burn up the coil. The 86 should use a resistance wire in place of the ballast resistor (my 84 does). To tell if you have a resistance wire, printed on the wire (red wire) is "DO NOT SPLICE". If you have spliced or changed the length, replace wire with normal wire and buy a $3 ballast resistor (it will get hot, that is normal, so place away from other wires).

If you get her to idle, fell the IM to see if it is getting hot. When those IM start going bad, then tend to get really hot. Also, try tapping on the module when it is running, especially when warm. If it cuts out when you tap on it, it's bad. Another thing you could try is pouring water on the module if it is hot. Cooling it off sometimes relieves symptoms momentarily.
If your IM is bad, I would suggest the MSD 6A. About $200 at Autozone right now, but well worth to money. Your engine should spark to a new life. You don't need the 6AL with rev limiter for that engine, that is a waste of another $50 you can save for beer in deer camp.

Less likely, but possible. What kind of air cleaner do you have? If you still have the stock one, look to see if the air baffles are opening up too. I somehow doubt you have the stock cleaner from the 86 with the 72 motor. Not even sure if it will fit the 2100. Anyways...

Good luck and keep us posted.
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post #11 of 33 Old 06-10-2017, 11:45 AM Thread Starter
wsmutch
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I'm off to camp tomorrow. I'll bring out a new IM and a camera for some pictures. Thank you!
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post #12 of 33 Old 06-10-2017, 01:00 PM
258
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wsmutch,

1. If you are questioning your fuel quality; considering the age, how often this sits and todays ethanol gas added to an already compromised fuel delivery system, you may want to start by cleaning out those areas. With this being said, run a REAL GOOD fuel additive to clean out the fuel delivery system and the lines. This will only aid in fuel quality and to ensure you're at least cleaned out within. If it's a clogged jet or small parts, in most cases it will clean these areas before they really clog.

2. Once you have run those additives, replace the fuel filters, the plugs and give her a general tune-up. Then, since you know all is well from before the carburetor, look into rebuilding it. Today's ethanol is bad for aging old rubber internal parts. Clogged jets and the accelerator pump within the carb are usually first to go since the fuel ends up there before its burned off. That rubber diaphragm at accelerator pump will be deteriorated, weak and get sluggish from build up. If its just starting, the fuel additive will start to clean those areas. So, if you do this first, you won't be feeding bad fuel again throughout the system. I just went through this and learned from my mistakes. Once I cleaned the entire system out and did pretty much everything else, my engine responds much better.

3. If you replace the ICM, still clean the fuel system. The additive I used was ARCHOIL AR6400-G.

Good luck!
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post #13 of 33 Old 06-12-2017, 09:26 PM Thread Starter
wsmutch
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Alright, I went to camp with a brand new Ignition Module. The old one looked a little rough, but no noticeable heat damage. I reconnected the battery and it started on the first try. I let it warm up, and the whole time it purred like kitten. I jumped in and started driving down the camp road. At exactly the same spot as before it started cutting out. A little farther and it died. So, like everything else, the new part was an improvement but not the problem. Its never started and idled better, I just wish I could go for a ride and not have to walk home.
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post #14 of 33 Old 06-12-2017, 09:39 PM
258
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Hmmm? The ONLY other thing I can suggest from my own experience is to check your alternator wires that connect at alt. back. The last time mine died like you describe was due to the main alt. lead wire being dried out, burnt and brittle. This was the wire that connects to the back from the solenoid. It was literally ONLY connected via a few copper strands. Once I replaced it with 10 GA. wire, it has never been an issue. At least check those wires. Even if they look good, remove them and gently wiggle the terminal end to make sure it's not brittle. Also, make sure all your ground wires are solid too. Good luck!
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post #15 of 33 Old 06-12-2017, 11:37 PM
Nucking1Futs
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258 could be onto something there. Broken wires means less strands which is more resistance. More resistance is more heat, which creates more resistance, which creates more heat.....it is a circular path.

If the coil/duraspark is not getting (I believe ~9 volts) she won't work. So, from alternator to coil and Duraspark check conditions of wires and connectors.
It could very well be high resistance creating a voltage drop. She idles fine, system is not being taxed or stressed very much. As you start driving, the demands increase stressing components.

The basics, fuel air spark. No vacuum leaks, manual choke, clean fuel, fuel pump working, (good fuel filter?). So, if you have ruled out fuel and air, then you have an electrical issue. Start at the alternator, battery, work your way in. Take something with you (like ice, water) that you can start cooling of components one at a time (reducing heat, which reduces resistance, which reduces stress). If she runs again, then you have located where in the system that is bad.

It's a PITA situation.
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