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post #1 of (permalink) Old 12-15-2002, 08:56 PM
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weber bucking problem

My CJ has been unfunctional for about the last two weeks. I put a new header and full exhaust (dual) on, and put a used Weber carb on. During the Weber install I also installed a new fuel filter. When I went for my first test drive after adjusting the carb the jeep would buck, hesitate until I let off the gas. The problem only occurs in third gear. First and second I can mash the skinny pedal and have no problems, but shift into third and right around 1500 rpm it starts to buck. I searched the old posts and found that this isn't uncommon. I adjust the float level and also routed the gas lines away from the headers (run along fender now), and I have the adjustable fuel pressure regulator set at 3 psi. I have zero emissions equipment hooked up. I have ported vacuum going to the distributor, PCV, and vent hooked up. I am not using the Charcoal canister or the EGR also, but both are still there just not hooked up. All unused emissions sensors were taken off and all holes were capped. I have been trying to figure out the problem for the last few days. What could cause this and what should I start checking?
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post #2 of (permalink) Old 12-15-2002, 10:54 PM
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Re: weber bucking problem

Do you have a fuel return line going to the tank? I don't on mine and I get vapor lock with the fuel at 3 psi. But I don't have any problems at 5 psi.
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post #3 of (permalink) Old 12-16-2002, 02:57 PM
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Re: weber bucking problem

Yes, I have a return line. I have even tried turning up the regulator to 5psi and it still bucks. First and second gear are fine and shift into third and its a buckin' same with 4th.

Anybody else have any ideas, I mean any.
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post #4 of (permalink) Old 12-16-2002, 05:16 PM
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Re: weber bucking problem

When you raised the float, did you notice any change? I had the same problem. It would run out of gas at about 40 MPH in third. Might need to raise the float up a little more. When it happened to me, I did away with the return line, trying to get more gas in the carb. That was a mistake. I now had vapor lock. I also increased fuel pressure. No change. The only thing that worked for me was to raise the float up a little at a time until the carb did not run out of gas. I really donít know why you have to do this. It seems that when the float drops down, it should let in enough gas to keep the jets covered. But it didnít. Just keep bumping that float up. Worked for me. Hope this helps.
post #5 of (permalink) Old 12-17-2002, 08:54 PM
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Re: weber bucking problem

The float adjustment didn't seem to help. But, while checking out the carb and thinking about it I might have found the problem, I think. My two barrel weber is only functioning on one barrel. I can see the fuel pouring into one barrel and nothing on the other barrel. I partially disassembled the carb and cleaned the small parts in carb cleaner, but it didn't solve the problem. What could be causing this and/or how do I track the problem down?
post #6 of (permalink) Old 12-18-2002, 06:05 AM
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Re: weber bucking problem

If it was a used carb, did you rebuild it before you put it on, or did you just put it on. Perhaps all it needs is a rebuild? Could be that it is gummed up and that is why you are not getting fuel. Take it apart and soak it in carb cleaner for a few hours. That stuff will take anything off. And if there is gunk in there the soaking should break it loose.
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post #7 of (permalink) Old 12-18-2002, 07:36 AM
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Re: weber bucking problem

Dumb question but....
How do you adjust the float level on a Weber 32/36?
I'm having the same problem with mine feeling like it starves for gas around 3rd gear.
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post #8 of (permalink) Old 12-18-2002, 04:24 PM
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Re: weber bucking problem

The secondary does not come open until about 2/3 throttle. It is a mechanical secondary, so if you open the throttle wide open and it does not move, something is wrong with the linkage. The Weber has two holes right at the throttle plate. They are called transition holes. At idle gas dribbles out one of the holes and as you give it more throttle, vacuum will pull gas out the other hole. As the throttle plate continues to open, gas will start to come out the ventures. At about 2/3 throttle, the secondary starts to open and the same thing happens on that side. At wide open throttle, the progression holes are not supposed to have any gas coming out of them. To raise the float, take the top off the carb and lift up a little on the float. There are two tabs on the float. One limits the drop and the other limits the height. Just lift it a little to bend the tab and see if you see a change. It did not take much to solve my problem of running out of gas. If you need more info, just E-mail me and I might be able to scan some pictures out of the book Iíve got. Hope this helps.
post #9 of (permalink) Old 12-18-2002, 08:47 PM
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Re: weber bucking problem

The idle jets in both the primary and secondary control transition circuits . Try running a larger size idle jet in the primary side . If you can't find any , I sell them and keep quite a few in stock since I'm a dealer . If you have any questions, just ask....
<img src=http://tellico.off-road.com/wwwthreads_uploads/778134-carbintake4.jpg>
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post #10 of (permalink) Old 12-20-2002, 10:33 AM
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Re: weber bucking problem

The secondary does open when the throttle is at wide open. What I see happening is gas is only squirting into one barrel. In this diagram part 82 is what the fuel is coming out of on the one barrel. I have taken the carb partially apart to clean it and that part only has one side drilled. Is that were the fuel comes out on the other barrel also.
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