Weber K551 34/34 DGEC idle problems -

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post #1 of 51 Old 07-23-2008, 10:38 AM Thread Starter
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Weber K551 34/34 DGEC idle problems

i have a rebuilt motor (258), and new ignition parts, but the carb will not idle properly. Once I am going, the carb seems to run fine through all the gears, but every time i slow to a stop, the carb just sputters out and dies. I did a search, and found things about different jets, and vacuum leaks. Are one of these my problem? When I first start the jeep, it seems to run ok for a little, then the idle kinda bounces around a little, the engine struggles and then stalls. Every time I start it up after this, it just sputters out. Any help would be greatly appreciated.

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post #2 of 51 Old 07-23-2008, 12:52 PM
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Do you have the idle mixture set appropriately? That's the first thing i'd check. The instructions should have come with your carb. If the mixture is way off, that would be a possibility. It's an easy adjustment. I'd start there first.
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post #3 of 51 Old 07-23-2008, 09:10 PM
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mine does that too, it works about half the time and the other half it sputters out and dies at traffic lights. I look like i cant drive stick. It has been working lately, and all i have done is try to adjust the mixture better.

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post #4 of 51 Old 07-23-2008, 09:16 PM
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I would look close for vacuum leaks.Spray some wd 40 around the base of the carb and see if the motor has a noticeable difference in the way it runs.

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post #5 of 51 Old 07-24-2008, 08:10 AM
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I had the same problem. You must follow the set-up sequence as noted here:
But do check for vacuum leaks as CJhollic suggested.
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post #6 of 51 Old 07-26-2008, 04:33 PM
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not one mention of a fpr..fuel pressure regulator..One needs to be installed and adjusted down to about 3lbs. to get the most out of the carb..

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post #7 of 51 Old 07-26-2008, 04:38 PM
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I've got this same carb and have had nothing but trouble out of it. I finally got it running smoothly, but it just runs WAY too rich and the exhaust fumes kill me. As soon as I can afford it, i think I'm going with fuel injection....but to get mine running even as well as it is a guy had to clip some of the springs out of the idle mixture screw to get more adjustability out of it and we sized the jets down to 45 in the primary and 47.5 in the secondary. I think that it would be better with a 40 in the primary and the 45 in the secondary myself, but that's just a theory....
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post #8 of 51 Old 08-15-2008, 06:56 AM
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Originally Posted by TripEph View Post
When I first start the jeep, it seems to run ok for a little, then the idle kinda bounces around a little, the engine struggles and then stalls. Every time I start it up after this, it just sputters out. Any help would be greatly appreciated.
I just installed this same carb in my '88 YJ a couple of days ago; one thing that got me started was to crank the choke screw all the way in, so you might want to try that.

Now it's running smoothly, but way too rich, so I'm planning on backing off the choke until it sputters, then trying to re-adjust the idle mixture according to the link posted above (thanks!)... the setup instructions (and blurry pictures) included with the carb weren't the best.
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post #9 of 51 Old 08-15-2008, 07:01 AM
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could be the fuel filter as well.

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post #10 of 51 Old 09-03-2008, 06:47 AM
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My 90 yj with the weber did the very same thing yours and after instaling an HEI distributer, it runs like a top and I'm waiting to see if my MPG increase.
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post #11 of 51 Old 09-03-2008, 10:50 AM
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It runs rich because you don't have a FPR installed. Even adjusted all the way lean, without a FPR the Weber will run way too rich.

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post #12 of 51 Old 09-15-2008, 12:44 PM
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1987 YJ Weber

I did the K551 conversion too, and it runs fine after I did the setup by the guide mentioned in some earlier post, and cranked the choke release screw way in. I also had to jet down to 45 pri 47.5 secondary to lean it out. My remaining problem is a tendency to flood while it sits in a parking lot after a 30 mi drive. Takes way too much cranking to clear the manifold, but it does finally start. I don't have a FPR in now, but I do have one of those fuel filters with a tank return at the Weber inlet. Stock fuel pump. I tried a Specter $25 regulator (Chinese junk!), but it just arbitrarily cut the fuel off completely at idle, so I put the tank-return filter back in. Weber says to use a regulator but doesn't recommend a reliable choice. Any suggestions? Is there any Web info on checking/setting the float level for a 34 DGEC?
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post #13 of 51 Old 09-15-2008, 12:48 PM
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post #14 of 51 Old 09-15-2008, 01:48 PM
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Yeah, I actually had my BBD running quite well after a season of rough idling. I took it apart and found a bunch of naptha crystals adrift in the floatbowl. After cleaning them out it idled and ran fine during the summer. I just did the Weber conversion for smoother acceleration and better cold-weather starting. My BBD's choke was cantankerous in winter.

I'm wondering if the Specter-type inline regulators are supposed to tee off the inlet line and go to the tank-return, instead of being in the line to the carb?
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post #15 of 51 Old 09-21-2008, 12:31 PM
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Answer to all pump and regulator problems

There is always one debate when installing a Weber. Check this page out.....

It shows how the Carter 4070 rotary electric pump is the one simple answer to this reoccuring question. It is a high volume low pressure rotory pump (constant flow, not a pulse like other crappy elec. pumps or like the stock mechanical pump.) Regulators only decrease the life of a pump. So why not find a pump that operates at your needs? The 4070 pumps at around 4psi but flow around 60-70 gph. Perfect for what any weber needs! It costs around $80- $100 and comes with everything you'll need except a little extra hose and wires. When I found this I was sold, I bought my Weber, did the Nutter bypass and only a little adjustment. Make sure the remainder of your vacuum lines that you use are routed properly and reset your timing on your distributer 14 degrees BTDC @1600 rpm.

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