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Discussion Starter · #1 ·
Hey Everyone, new to the forum. Read many of your posts regarding similar problems and fixes. Unfortunately they are still coming up short. Here is the issue.
87 with the AMC 258 4.2L. Carter 2 BBL Carb, (don't give me crap just yet). Does not have nutter bypass.
What I did:
Replaced the head gasket and all main gaskets there up - Valve Cover, Temp Gasket, Intake and Exhaust Gaskets. Cleaned up the head while I was in there. Removed valves and took the gunk off of the valves since what I saw was probably there since 1987. Installed new value seals and flushed everything out. New serpentine belt. New plugs.
Cleaned carburetor out of dirt and grime. Only thing I removed was the choke plate and the two screws directly below it to blew it out with cleaner. Ensure everything was in place to include the small ball bearing.
Reinstalled everything to spec. Started up on the 2nd turnover. Sounded fine. Checked timing, had to adjust a few degrees.
Instructions I got for the timing through the forum. Plugged vacuum advance from distributor. Set to 1600 RPM and adjust to 9-11 BTDC. Tighten and reconnect lines. Did not jump around at all. Seemed fine.
Drove the jeep to work for the day, seemed fine. Started up next day, didn't make it to the end of the street before it was stalling out. Thought nothing of it and continued, died again. Thought the idle was set to low. Had to start it 3 more times heading back to the house to get another vehicle to head to work.
I have adjusted timing over and over. Checked the carb. Blew it out again. I can get it to idle fine, but the second you push the throttle wide open it dies out. That is the problem.
Could not find any vacuum leak after spraying vacuum lines and intake. It is pulling around 23 inches. Seems normal.
All cylinders have good compression in normal operating ranges.
I am leaning towards the carb since that is all I hear about being the problem.
Prior to replacing the gaskets it ran fine, just leaked oil. Not from the head gasket as it turned out, but what the heck. It has a new one now. Rear Main seal is next.
Any help would be greatly appreciated.
 

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before it dies, does it stumble or just go right to dead? If you increase the rpm's while stopped does it die or only when moving? I would double check the vac lines, and the carb... my CJ would die... unless I had it real high rpms it would die when coming to a stop.. vac line was not all the way hooked up... and fuel metering tubes(looks like two fangs) on the carter needed cleaned.
 

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Discussion Starter · #3 ·
If you ease into the throttle it will increase to redline. If you are already at 1500 or above and go wide open, it will do that just fine. But from idle when it is wide open it dies.

The main throat in the carb is clean. I blew everything out with carb cleaner. To include the "fangs" to ensure they weren't obstructed.

I've tried to find a vac leak but I'm out of ideas. I can't find one.

I still get solid sprays out of the carb when pressing throttle.

Thanks
 

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well I am sure some one with better idea's than mine will chime in... wish I had something better to offer.
 

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Discussion Starter · #7 ·
I thought about that. If I hold the choke plate down I can open it up from idle with no problem.
I read some where to check the accelerator pump to press quickly on throttle when it is off to test and see if fuel comes out when it is off to feed more fuel. It did what test said to do. Unless that was something completely different.
 

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Also make sure your float is correct and not sticking. Both are symptoms of what you're describing.
 

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So I have that same engine and setup.

The best way to check your fuel pump is to disconnect in front of the fuel filter right by the carb.

Put a plastic soda bottle over the hose and have some one crank it while you hold the bottle it should pump fuel as it cranks.

Also Chang the fuel filter if you have not already and make sure the vent line goes to the evap can under the washer fluid res.

Lastly the fuel filter lines should be over the top of each other not side by side.

Also take some close up pics we can see things better than describe them.

So if you have not Nuttered yet why did you adjust the timing so far?

Chief
 

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Discussion Starter · #11 ·
Lastly the fuel filter lines should be over the top of each other not side by side.

Also take some close up pics we can see things better than describe them.

So if you have not Nuttered yet why did you adjust the timing so far?

Chief
Did not realize that about the fuel filter with lines running on top of each other. I would assume the output that is offset from center goes on top?

Just got back. Will post up some pictures to see if something looks off.

The timing in the manual says to set to that. 9* +/- 2. Is that wrong and where would I find that information. Have not seen anything searching the forum.
 

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So I am not sure what manual you are using I had mine set at 8 BTDC before I switched over to an MC Carb and Nuttered.


It ran fine that way for awhile but I always seemed to have to adjust it.

The issue you are having is common as you probably have read.

If you are set on the carter I would check all hoses for leaks and check all vacum connections.

It honestly sounds like a vac leak.

Pics will help no matter what

Chief
 

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I may be wrong but it looks like you had the fuel line hooked to the Evap can, if so it may be full of gas and causing something bad to happen. IDK
 

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Discussion Starter · #16 ·
If you are set on the carter I would check all hoses for leaks and check all vacum connections.

Chief
I am not set on the Carter, I will switch it fairly soon, but I am trying to ensure that the problem is actually the carb first. I don't want to end up ordering the carb and then still have the same problems.

The Weber I was looking at was the Weber 38 DGES along with the fuel regulator to solve the pressure inconsistencies.

I will problem grab some new vacuum hose and replace lines in the morning to eliminate leak issues. Shouldn't take long.
 

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Discussion Starter · #17 ·
Also make sure your float is correct and not sticking. Both are symptoms of what you're describing.
Pulled carb off this morning. Cleaned, checked float and other components, and reinstalled.

New symptom though, will only start at higher rpm and now dies at idle. I can keep it running with it over 2K.
 

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Pulled carb off this morning. Cleaned, checked float and other components, and reinstalled.

New symptom though, will only start at higher rpm and now dies at idle. I can keep it running with it over 2K.
Sounds like it's time to replace the carb.
 

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Discussion Starter · #19 ·
Ok, slight overlook. Forgot to plug up one of vacuum tube to carb. So forget about the no idle problem.

Main problem still exists. I can get it to idle better now where it is supposed to be around 750. Couldn't do that before.

When timing is at 9 BBC the throttle problem is noticeably bad. When it is up past 16 or so it is there but not as bad.

Probably does help figure out the problem though.

It does spudder at idle though.
 

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Discussion Starter · #20 ·
Update:

Timing is set at 9* +/- 2 as per what the manual says and what is under the hood at 1600 rpm with the vacuum advance plugged.

I am replacing all vacuum lines right now, just took a break for a few.

I took it out for a drive, and it drives fine at all RPMs. The only issue is the quick throttle response from idle makes it die. If you ease into it, it runs fine.

Here are my thoughts: (Not an any particular order)

1. The pump is not working properly.

When wide open from idle, it is either getting too much fuel and flooding itself out or it is not getting enough fuel and getting too much air when the carb opens up and killing itself.

I can look in the carb and see good healthy sprays when I hit the throttle and it runs fine at higher RPMS.

2. The carburetor is the problem. Do not know what exactly is wrong with it though.

I am pretty savvy when it comes to figuring out problems, but I cant get wrapped around this one. If someone needs something tested, let me know and I will do what I can. I need to get this back up and running correctly.
 
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