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Discussion Starter · #1 ·
I went four-wheeling to a spot in town, I drove through a mud hole which covered my 33inch tires, my distributor isn't wet, changed my fuel filter, checked vacum hoses to carb. Now my Jeep will start and drive fine, when I push in the clutch or idle the engine will idle sporatically for 5 seconds then quit. And ideas on what to check or replace?


Thanks
Never Summer
86 cj-7 3inch Lift 4.2l 33x12.50
Nev

 
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Discussion Starter · #2 ·
The first thing to do is tighten up all of the intake/exhaust manifold bolts, they have a tendancy to work loose. If some are missing, replace them. You may find that there are some broken ones at the front or rear of the exhaust manifolds, or that the exhaust manifold has warped and covered up parts of the holes in the head where you need to replace a missing bolt. This may require replacing the manifold or, if it's not too bad, grinding or filing away some of the manifold for clearance. If you find that the intake gasket has blown out, don't use the aftermarket combination intake/exhaust gasket. The exhaust manifold should be bolted straight to the cylinder head. The typical Fel-pro McCord or Victor exhaust gasket will leak vacuum between it and the intake gasket (that is stapled to it) after a short while. The factory uses only the intake gasket part of the aftermarket set.
The second thing to check is the carb itself. There are small tubes inside called emulsion tubes that get plugged quite easily with dirt/rust/carbon blown in through the pulse air system. If the inside of your air cleaner has any particles of dirt, they may have got into the carb and plugged up the tubes. This causes a lean misfire condition at idle. Sometimes you can clear the blockage with carb spray. Using a nearly full can with a long nozzle/tube, put the nozzle right into the holes in the venturi screws visible inside the throat of the carb. Give each of them a good blast of carb spray while keeping the engine running at a fast idle. Use caution as a backfire may result in flames!
If the engine now runs better, the jets were plugged. The dirt is still in there though, so you should, at least, take off the top of the carb and clean out the dirt. The root cause is usually the pulse air system deteriorating and sending rust/carbon particles into the aircleaner housing. A plugged or partially plugged catalytic converter also will cause the valves in the system to fail. The pulse air system parts would cost around $250-$300 at the dealer to replace the 2 switching valves, the 2 check valves, and the 2 metal tubes.
Hope this helps, good luck!

 
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Discussion Starter · #3 ·
whenever i go through water and then have engine trouble my first guess is always either the TPS or MAP sensor connected to the throttle body. they REALLY dont like water. you might want to check on those.

'95 YJ with mods
 
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Discussion Starter · #4 ·
No MAP or TPS on a carbed CJ, but good advice for others with the same type problem and EFI!

 
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Discussion Starter · #5 ·
My emulsion tubes are probably clogged with dirt, I just bought a new air filter today, the other one was really dirty, I also purchased a bottle of carb. cleaner, I will use this to try to clear any dirt that might clog these tubes. Thanks for the advice

Neversummer
86 CJ-7 4.2L 33x12.50

 
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Discussion Starter · #6 ·
I cleaned out my venturi screws, they have small holes in the center, I really didn't notice a difference, then I turned my idle screw 1.5 times to the right, I wasn't sure what effect it had on my idle. My engine ran now at about 400-500 RPM, it was a little shakey but didn't stop. I then drove around my block and retured home, everything was fine, just when I pressed the cluth in or had trans in neutral it would go up and down about 200 rpm then settle down at 500. I got home and adjusted the idle screw back to the position it had been before I messed with it. Could the idle maybe have been a temporary fix?

Neversummer
86 CJ-7 4.2L

 
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Discussion Starter · #7 ·
Yes, probably temporary. There may have been dirt inside the idle circuit that cleared itself out after you moved the idle screw. Sometimes the carb spray procedure takes a few tries to work, also. The top of the carb is pretty easy to remove, as far as modern carbs go, and can be done with the carb on the Jeep.
If you don't tear the gaskets, you won't need a carb kit. Start by removing the small clips from the choke linkage, the accelerator arm and the fast idle cam. Then remove the 3 small screws from the top bowl cover, (DON"T TOUCH THER ADJUSTING CAM SCREWS INSIDE !!!). Next remove the 6 top cover bolts, and carefully lift off the cover. Remove the gasket carefully,if it stuck to the main bowl. Take out the 2 screws you blew the carb spray through, and remove the venturi assembly. The emulsion tubes are brass and have a very small hole on the bottom end, this is where they plug up. Blow them out with carb spray or shop air, being careful not to bend or damage them.
watch out for 2 small ball bearings, one under the accelerator pump, the other under the venturies, these are for the accelerator pump circuit, remove them out of the carb with a magnet and set aside, (noting where the large one went). remove the return spring for the metering rod vacuum piston also at this time. Watching your eyes, in good ventilation, blow out the carb bowl and jets with carb spray and shop air, if available, until all of the dirt is gone. Reinstall the spring and check balls in their proper locations. Reinstall the top, being carefull to get the metering rods to line up with the main jets, along with the vacuum piston and accelerator pump.
If you suspect dirt entry through the pulse air tubes, you could unplug the hoses from the air cleaner housing. Cap off the housing tubes with corks or plastic caps, the same with the pulse air hoses(or rig up separate small air filters). This would keep dirt and rust from entering the housing and carb again after you clean it out. (The above is for "testing purposes only", as it would not be "smog legal"!!!)
Hope this helps, good luck!

 
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