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Unread 11-30-2008, 10:31 AM   #1
defmornahan
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1987 YJ Wrangler 
 
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Weber 34 - choke plate won't open??

I put a new Weber carb (34/34 from Quadratec) on my new Jeep a few months ago. A little while back I noticed that my fuel line was kinked because the fuel inlet barb was all the way on the fender side of the carb. I changed the fittings around to the middle and shortened the hose.

Now, I THINK I readjusted the idle settings on the carb shortly thereafter, but maybe I'm mistaken. Anyway, I had electrical problems for quite a while afterward and couldn't get it started; then once I fixed them, it would start, run for maybe 15 sec, and quit. I thought it was a vacuum leak or something, tightened the carb down and fidgeted with some hoses, but no luck.

I thought maybe it was running too rich (I don't judge smells very well...) I took the air cleaner off and noticed the choke plate was tightly shut, so I propped it open with a screwdriver. She started right up and began to roar, so I figured I'd found the problem. But I can't seem to get the choke plate to open up, no matter how much I adjust the choke pull-out or fast idle screws. I did put a fuel pressure regulator on and turned it down to 2 psi, which seemed to help, but I think I'm just masking a problem. (I also just flooded the beast with Sea Foam...I propped the choke open and got it started again, but...) It used to start choked and revving high, then when I tapped on the accelerator it would fall off. Now tapping the accelerator does nothing. Is there something broken on the carb? What do I look for?

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Unread 11-30-2008, 10:39 AM   #2
Old4X
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You have 2 options. 1, fix the automatic choke. or 2, convert to a manual choke.

From your post, it sounds like going to a manual choke is your best bet for a fast, inexpensive fix.
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Unread 11-30-2008, 05:18 PM   #3
defmornahan
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Do you have any details on how to do either one?

I followed the wiring to the choke switch on the engine block and noticed that those wires had broken insulation and corrosion down in the exposed copper. I also noticed that the fitting could be put on either direction. I wondered if I had the wires backward, since I was checking all the wiring recently. Has anyone got a carbureted YJ 6 cylinder with a working choke who can tell me whether the blue wire or the orange wire is on top of that connector? It's on the passenger side of the block, low down, not too far from the oil dipstick.
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Unread 11-30-2008, 05:21 PM   #4
defmornahan
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PS I did, of course, also cut out the corroded wire and put some new connectors on. I've also checked and made sure that the choke plate is not stuck.
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Unread 11-30-2008, 06:55 PM   #5
ctm
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Orange comes into the electric choke switch from ignition 12V. Blue comes out of the switch to the choke (and branches to the manifold heater relay and to a diagnostic port).
By the way this is why there are those diagnostic connectors near the battery (the ones with rubber covers). you can check for 12V for the choke by probing Diagnostic 1-2, that is the small 6 port unit, middle port on the side with the zigzag shape. Do you have a multimeter?


Try testing your choke by temporarily running 12V directly to the choke and see if it opens up in a minute or two. If it does then it's fine, and your problem is with the wiring like you said.
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Unread 11-30-2008, 07:53 PM   #6
Old4X
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Quote:
Originally Posted by defmornahan View Post
Do you have any details on how to do either one?

stick.

Most auto parts places used to sell universal manual choke kits, I haven't needed one in years, but NAPA and Summit Racing still have them.

edit to add: Quadratec should have the manual choke kits for that specific carb as well.

They are very simple, just a cable and a bracket that attaches to the carb.

Last edited by Old4X; 11-30-2008 at 08:24 PM.. Reason: add info
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Unread 12-01-2008, 05:24 PM   #7
defmornahan
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Quote:
Originally Posted by ctm View Post
Orange comes into the electric choke switch from ignition 12V. Blue comes out of the switch to the choke (and branches to the manifold heater relay and to a diagnostic port).
I know what they DO--for once the Chilton's wiring diagram did not lead me astray (!)--but I wanted to know if one wire needs to be on top or if the order doesn't matter. Based on some other reading, I gather that it's a simple naturally open switch and the order shouldn't matter.

I have a multimeter, and I know about the diagnostic port, but somehow I've never put the two thoughts together...

In any case, it really seems like all this electrical stuff is a red herring. I want to know why the choke is not responding to me tapping the accelerator like it used to, and I have to think that's a mechanical issue in the carb itself.
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Unread 12-01-2008, 09:06 PM   #8
ctm
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Still, the fast idle cam won't respond unless the choke opens electrically.
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Unread 12-01-2008, 10:05 PM   #9
defmornahan
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I just checked the leads at the diagnostic connector. 13-some volts between the blue choke wire and ground while the engine is running.

I was examining the fast idle control and cam and noticed that I could open the choke by rotating the cam, and then when I pushed the throttle linkage the choke would pop back closed. I just wonder why it won't open when it's running.

My friend was fiddling with the "choke pull-off" screw and we noticed something disturbing: he pushed in on the screw and THEN turned it, and we found that the choke plate won't move as far when we push on it even after he's backed the screw back out. So I really think something mechanical has gone awry.

With the engine running, I lifted the air cleaner and stole some peeks at the choke plate. It did open a small amount, and would open a tiny bit wider if Aaron touched the accelerator, then go back when he let off.

If I can't get hold of the Weber support line again tomorrow, I may have to take the beast to one of the carb shops around here and have them look at it. I'm getting sick of it and worried that I'm going to fiddle too far with something and break my new carb for good and all...
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