New 85' CJ; won't idle

[ridegnu]

Ok Breakdown:

1985 CJ7 AMC AMC 258 i6 / 4.2l I6
5 spd
Weber Dbl Brl 32/36 carb

Looks to be fairly stock motor, the carb looks modified; no choke plates, rectangular instead of circular air filter.

The guy I got it from said that his buddy mentioned that it needed a valve job. It was blowing white smoke untill he put some additive in the oil to prevent that, is what he said.

Seemed to drive here fine and was holding a rough idle once the engine reached operating temperature.

I took the carb off & cleaned it, replaced the master brake cylinder, new air filter, inline fuel filter. I forgot to buy new spark plugs, when I pulled them they were and burnt/rusty red but not oil fouled. I cleaned them, gapped them, and put them back for now. Wires appear new, routed correctly, rotor and cap also in good shape. Going to replace spark plugs and test cylinder compression tomorrow.

I drove it around the yard a bit this morning and it seemed to idle roughly, then i let it sit for a bit. came back about 4 hours later and let it warm up again and it wont hold idle now.

Thought it might be low on gas, filled it up & replaced inline fuel filter.
I could only find an inline fuel filter, nothing else. Is there a filter in the tank? I know that the jeep was parked for the last 8 months without fuel, and i know got poured into the tank.

So far I am debating blowing my fuel lines out, draining my tank, looking for an air leak.

Any thoughts?

After reading a couple other posts on here it seems that vacuum leaks around the carb can be problem causing, as well too much fuel pressure (>3psi) to the weber is a problem.

I would let to set the weber back to default settings, but i'm not sure ho much to mess with things, I know this jeep was running good at one point but that could of been years ago. The previous owner never touched, fixed, or maintained anything.

 

[Saddle Tramp]

White smoke means water to me and would indicate a blown head gasket over valves but I’m not an expert on that subject. Blue would indicate oil burning from bad rings, valve stem guides, etc.

Vacuum leaks would be the first thing that I would check. You can spray a little carb cleaner on the suspect areas around the base of the carb with the engine running, if the rpm picks up you found a leak. Check all of the hoses, replace them if brittle and I would make sure there aren’t any air leaks in the fuel line too. Who knows what the PO did when the Weber was swapped in and the hoses may not be hooked up properly.

In my experience when it comes to a Weber carb you either get a good one or a bad one. They are kind of a finicky carbs and proper jet size can make a big difference. Many use them and have good luck but I have a $400 horror story and Weber basically said too bad so sad and left me hanging; there is a reason it says on the outside of the box they come in “No Warranty What So Ever”.

Another thing to do is a compression test and a leak down test, that will tell you a lot about what is going on with the rings and the valves but if it was mine to do I would eventually swap in a MC 2100 and loose the Weber.

 

[thescot]

White smoke means water to me and would indicate a blown head gasket over valves but I’m not an expert on that subject. Blue would indicate oil burning from bad rings, valve stem guides, etc.

Vacuum leaks would be the first thing that I would check. You can spray a little carb cleaner on the suspect areas around the base of the carb with the engine running, if the rpm picks up you found a leak. Check all of the hoses, replace them if brittle and I would make sure there aren’t any air leaks in the fuel line too. Who knows what the PO did when the Weber was swapped in and the hoses may not be hooked up properly.

In my experience when it comes to a Weber carb you either get a good one or a bad one. They are kind of a finicky carbs and proper jet size can make a big difference. Many use them and have good luck but I have a $400 horror story and Weber basically said too bad so sad and left me hanging; there is a reason it says on the outside of the box they come in “No Warranty What So Ever”.

Another thing to do is a compression test and a leak down test, that will tell you a lot about what is going on with the rings and the valves but if it was mine to do I would eventually swap in a MC 2100 and loose the Weber.

What he said X2

 

[ridegnu]

En route to bringing the jeep to my place I followed the owner while he drove. I never saw any white or blue smoke around the vehicle at all. However whilst going through the engine bay once the vehicle was back I noticed white smoke coming out of the hole in the back of valve/rocker arm cover? I believe I'm using the right term, it has two holes on the metal cover, one at the front for oil fill, and the one at the back for who knows what.

Considering the condition the spark plugs were in when I pulled them (they looked considerable rusty on the armature set when gaping). Which perplexed me quite so, but water in the fuel or a blown head gasket would make sense.

So I will buy some carb cleaner, fuel and vacuum lines, pipe clamps, new head gasket, carb->intake manifold gasket, and spark plugs.

My only question is you said to spray the carb cleaner around the base of the carb, is this where it meets with the intake manifold? Or are you referring to somewhere else?

 

[Jimbos76cj]

Spray it all around.. If theres a leak it will get drawn into the intake and cause the idle to increase. I would keep an eye on the water and oil levels. If you have a head gasket leak you will get water into the oil. IF your oil looks brown and gloppy then you have a leak. If your water level is going down with out a visible leak then same thing. The smoke you see coming out of the back of the valve cover is from the PVC valve not being installed. I would start with a compression check and leak down test. IF those come up good I wouldnt pull the head yet.

All motor will have a small bit of compression leak past the piston rings which will cause a positive pressure in the crank case or bottom half of the motor. The more worn your rings are the more pressure you build up. If you dont have a PCV system set up correctly that pressure will build up and cause lots of weird small oil leaks or one big one. If the hole at the back of the valve cover is open your system is not correct. There should be a PCV valve on the hole with a hose going to either the air cleaner, carb, or intake. Or at a absolute minimun you should have a breather filter in the hole. Since the PO installed a weber you dont have the stock air cleaner that has the adapter for the pcv line. I dont think the weber has a port for one.

When they are installed correctly the vacuum from the motor will draw those vapors and gasses back into the intake and reburn em keeping the pressure down in the crack case

PCV VALVE OPERATION - YouTube

I wish I could give you some help with the weber but Ive had no luck with em so any jeep I own I pull the weber off and replace with a 2100.

 

[ridegnu]

Jimbos76CJ, thank you for your reply, very imformational, and clear.

I have to admit that I have not done enough research yet into this AMC 258 i6 / 4.2l . I am just running on my previous motor experiences.

So today I replaced the spark plugs, wire routing is correct, new air filter.
Noticed the the line from the brake power booster to the carb had slipped off.
Charged battery, cleaned terminals.

Won't start!

Blew out fuel lines, primed fuel pump, tested (disconnected line, cranked motor, steady even fuel surges), primed filter, fuel coming through the jets in carb. Sufficiently cranked starter multiple times, tried a little quick start here and there. Completely lost.

It drove here fine, started fine the next day (morning). Cleaned carb & replaced, started & drove around (forgot to attach brake booster to carb line), that is when I noticed funny idle, shut down.

The only thing I noticed is off the ignition coil comes three wires, and one is bare and floating. I assume this should be connected, but not sure.

 

[ridegnu]

Progress update;

Found no spark, pulled rotor cap, found copper tab broken off rotor glued back together for now. Cranked it and it fired once for about 5s then died, cranked again and nothing. Thinking battery is too low at 11v slapped it on the charger.

Going out for new rotor.

 

[ridegnu]

So confused. New rotor and cap, still nothing.

I got the wiring diagrams and started in. Their are cut wires everywhere, broken shields, exposed wires and connections.

Looking at the ignition coil I noticed a floating wire, end exposed (red wht). I found the other side of it, was poorly tied into 3 black wires which two seemed to run to a door shut sensor, and the other a plug in the fire wall. Wired the + side of the ignition coil directly to the + side of ignition solenoid bypassing the door lock sensor wires, which seemed to be aftermarket?

With KOEO I took two diffferent readings from the positive side of the ignition coil and got 6v on the first reading and 7v on the second. So the coil has power. Layed a spark plug on the block and cranked didn't see any sparks.

Grabbed a scope to try a SPOUT test and a ignition distributor test, no results.

I tested the resistance on the ignition coil and I am pretty sure it's out of acceptable limits. I am just wondering before i hook up a new one could I of blown it by sending excess voltage to it from imporoper wiring? manual says voltage should read 6v at the top of coil, what happens if it read 12v?

Old Coil Readings; Outisde + & - terminals = 1.4 Ohms
Outside - & center + terminals = 8400 Ohms

New Coil Readings; Outisde + & - terminals = 1.4 Ohms
Outside - & center + terminals = 9300 Ohms

So I am starting to think it's not the coil since even the bra new one is out of acceptable limits @ 1.4 (1.13-1.23) & (7700-9300)

 

[Neuner]

Hate to hear that the PO put in an additive for the smoke. From what I know, that is a temporary fix that makes the seals swell to stop the leak but it also softens them up and they then wear out more even quicker. The condition will only get worse.

Too many times I've seen a bad ICU causing your problem including for myself. The OEM units go easily right next to the engine heat.