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Rough Idle on 1990 Jeep Wrangler

I've had my 1990 Jeep Wrangler for about 5 years. For a while now though it has had trouble keeping a steady idle. Labor Day weekend, I had to get a new engine for it, and I thought the mechanic could tune the carb so it finally idles correctly. He told me though that he doesn't understand the electric feedback carburetor systemt and to try someone else. So here is what it does.

It won't idle at all now, and the idle screw is turned almost all the way in, When it did idle it keeps sputtering after i turn it off. It idles fine while choked when it is cold, but when the choke goes off and it warms up, it can't keep running. I was reading on others and they mentioned egr valve, but then again I don't know to much about the egr valve. When the jeep runs the egr pulsates in and out and doesn't just open and stay open or close and stay close, is this how it is supposed to work or is it supposed to open and close as necessary. Hopefully one of you Jeep lovers out there can help me out.

Jacob

Reply to
Jacob_T
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Reply to
Steve Foley

One common failure is the charcoal canister. When it fails totally, the idle will surge which will make the EGR go in and out or just not want to work and a pile of oil gets puked into the air filter imitating a blown engine...

To test this, you follow the PCV line from the front of the valve cover to the back of the carb. At the back you will find a t fitting or a solenoid thing with another line coming off it. This other line goes way down behind the fender to the top of the charcoal canister. At idle pinch this line closed. If the idle changes, the canister purge valve is dead.

You can take this line off the canister and plug it at the carb 'temporarily' to set the carb up right. You will need this canister plugged back in to avoid a lot of gas fumes because the canister is the vent for the gas tank and float bowls.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail >
Reply to
Mike Romain

Checking the idle tubes turned out to be fruitful as they were nearly completely clogged. Thank you for you recomendation.

Steve Foley wrote:

Reply to
Jacob_T

Reply to
Jacob_T

Reply to
L.W.(Bill) Hughes III

left

Reply to
L.W.(Bill) Hughes III

Just a FYI for you. The tube that runs from the gas filter and loops down to the carb has a tendency to get junk in it from gas evaporating when it sits. This junk is after the filter and can easily get back into the idle tubes.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail >
Reply to
Mike Romain

How do you clean that... GumOut?

Reply to
billy ray

I use spray carb cleaner.

Mike

billy ray wrote:

Reply to
Mike Romain

Reply to
Jacob_T

Yours has the feedback carb working right?

That means you seat the idle screws and back them out about 5 turns and get it warmed up then set the idle speed to 650. It might smoke a little.

You then turn the screws in in 1/4 turns at a time each and rev it. Keep doing this until the idle drops and the engine starts to rumble. You then back them out until you get the fastest idle. You then are supposed to bring them back in 'just' until you notice a slight drop in idle or 50 rpm max.

If this takes longer than 3 minutes to do, you are supposed to rev it to

2000 rpm in neutral for 1 minute to reset the computer and O2 I believe.

This should have the pins at the back of the carb cycling around the center of their movement.

Mike

Jacob_T wrote:

Reply to
Mike Romain

Yeah, it has the feedback carb. Thanks a lot for your help, this group is pretty neat, I am new to it, but it has helped me out tremendously. Thanks again.

Jacob

Reply to
Jacob_T

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