If I crack open the top of my Weber carb, my idle issue disappears??? - JeepForum.com

 
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post #1 of 6 Old 07-17-2011, 08:13 PM Thread Starter
unlucky
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1989 YJ Wrangler 
 
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If I crack open the top of my Weber carb, my idle issue disappears???

I've been struggling with this carb for a while now.

So far, I've fixed a big air leak on the adapter plates. Also found where the PO put a homemade gasket in the choke diaphragm, which was causing a leak there as well. I also had some float issues and was starving for gas. I'm really surprised this thing even ran.

But I still have an intermittent idle issue. Sometimes, when I start the engine, it idles great. I can turn it off and turn it back on and sometimes it will idle great, sometimes it won't. It's definitely a lean issue because if I cover the intake with my hand or with the choke plates, it idles smooth.

Well, this afternoon I was checking the bowl level, again, and happened to lift the top cover off the carb as it was running to make sure I was getting good fuel. It instantly started running better.

If I put it back on, it still wouldn't idle great, but at least it wasn't dying. I put it on and off a few times and sometimes it would idle better when I put it back on, but it always runs better when it's off.

So I checked the power valve and it will not hold vacuum when I push it and close off the port. I just ordered a new one. Is there anything else that would be affected when I crack open the top of the carb??

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post #2 of 6 Old 07-17-2011, 10:57 PM
monkeyhouse
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1997 ZJ 
 
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Location: Cumberland, Maryland
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Quote:
Originally Posted by unlucky View Post
I've been struggling with this carb for a while now.

So far, I've fixed a big air leak on the adapter plates. Also found where the PO put a homemade gasket in the choke diaphragm, which was causing a leak there as well. I also had some float issues and was starving for gas. I'm really surprised this thing even ran.

But I still have an intermittent idle issue. Sometimes, when I start the engine, it idles great. I can turn it off and turn it back on and sometimes it will idle great, sometimes it won't. It's definitely a lean issue because if I cover the intake with my hand or with the choke plates, it idles smooth.

Well, this afternoon I was checking the bowl level, again, and happened to lift the top cover off the carb as it was running to make sure I was getting good fuel. It instantly started running better.

If I put it back on, it still wouldn't idle great, but at least it wasn't dying. I put it on and off a few times and sometimes it would idle better when I put it back on, but it always runs better when it's off.

So I checked the power valve and it will not hold vacuum when I push it and close off the port. I just ordered a new one. Is there anything else that would be affected when I crack open the top of the carb??
what carb do you have?

First Jeep was an 1989 YJ, 6 cylinder 4.2L , 258. Nuttered and TeamRushed, Weber 38 DGES, Now, I'm venturing into the world of Grand Cherokees
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post #3 of 6 Old 07-18-2011, 05:26 AM Thread Starter
unlucky
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Weber 32/36 DGEV
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post #4 of 6 Old 07-23-2011, 05:43 PM Thread Starter
unlucky
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Anyone? I just got done rebuilding/cleaning my carb with a major kit (including viton needle valve and new power valve). It didn't change a thing.

But still, if I crack open the top half of the carb it runs great and will continue to run great after I close it back up for a few seconds. Then it starts getting rough again until I crack it open for a second. It makes a pretty loud hissing noise when I do this.
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post #5 of 6 Old 07-23-2011, 06:16 PM
oldtime_ironman
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1991 YJ Wrangler 
 
Join Date: Dec 2010
Location: 14304 Niagara Falls
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Quote:
Originally Posted by unlucky View Post
Anyone? I just got done rebuilding/cleaning my carb with a major kit (including viton needle valve and new power valve). It didn't change a thing.

But still, if I crack open the top half of the carb it runs great and will continue to run great after I close it back up for a few seconds. Then it starts getting rough again until I crack it open for a second. It makes a pretty loud hissing noise when I do this.
I'm not familiar with weber carbs but it sounds like something still isn't quite right. The hiss noise is a clue that its looking for air somewhere. Also the way it ran better with the lid off. So maybe its too rich in the idle circuit with the lid on. You might want to pull it down again with another kit. I used to use old guitar strings to clean out the crud from all the tiny holes and passages on chevy carbs. Maybe that would work for you too.
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post #6 of 6 Old 07-23-2011, 06:29 PM Thread Starter
unlucky
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1989 YJ Wrangler 
 
Join Date: Mar 2011
Posts: 103
Question:

If I cover the primary choke plate opening, it runs better. If I cover the secondary only, it doesn't change anything.

Is the secondary idle circuit supposed to dump fuel in during idle or is it only the primary? Because I don't think my secondary is dumping any fuel in at idle.
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