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Guest Message by DevFuse
 

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just put in weber. idle problems.


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7 replies to this topic

#1 bratlife

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Posted 28 February 2010 - 02:09 AM

I just put in new weber in my 85 brat. I followed all the steps about adjusting the mixture first and then the idle next. It fired right up and ran great for a few days. but it just started acting up. It will barely idle and sometimes will actually die and while driving it runs like crap and maybe has slightly less power than it should. then it mysteriously fixed its self. then it started running crappy again. I feel like the carb is adjusted right so i am wondering if something is wrong with the vacuum lines. like a small air leak or maybe I capped something off that I shouldn't have. has anybody experienced anything like this? any ideas? I have read all the threads about the pcv hose routing and I think mine is good, but everybody talks about how confusing it is and that everybody does it wrong, so it kinda worries me. if that was wrong could it act like this? I would post a picture but I can't figure out how to attach a jpg. sorry. thanks for helping me out.

#2 ihscout54

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Posted 28 February 2010 - 11:23 AM

Sounds like a choke problem to me, thats easy to check. Im going to assume you removed the old vacuum valves and plugged the unused manifold ports (theres only a couple). You should check the carb base for leaks, the gaskets that come w/some of the weber kits are junk, and the base of the carb often has a poor finish. It is also possible that the fuel is contaminated and the jets are getting plugged up. My only other thought is to check your plug wires and ingnition system. Make sure your vacuum advance is hooked up to the right port, and is working right. Next time its "running like crap", just unplug it and cap the line to see if it makes any difference.

#3 bratlife

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Posted 28 February 2010 - 02:02 PM

Thanks a bunch for the response. I think most of that is good, I just had my distributor rebuilt and had a new vacuum advance put on it. I sprayed around the base of the carb and everywhere and seemed fine. All the plug wires are pretty new. It started not idling for the first time while it was completely warmed up- could that still be the choke? I took all the vacuum lines out and everything i didn't need (looks so much better under the hood without the "spaghetti bowl"of vacuum lines and valves). I capped everything. I read that you have to leave the fuel tank vent line open to the air and NOT to cap it. but what is the fuel tank vent line under the hood? I was a bit worried that I had maybe capped something I shouldn't have. The most frustrating thing is it is one of those self fixing issues so its hard to check things, also makes me think it might be a vacuum leak.

#4 ihscout54

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Posted 28 February 2010 - 03:08 PM

If the choke is sticking it will cause symptoms you are describing. What kind of choke do you have? You can pull the air cleaner when its acting up and make sure the choke is fully open, and that its not flooding. Does it smoke when it does this?
A simple check for the tank vent is, when it starts doing it, open the gas cap, if that eliminates it youve found your problem. Have you checked your fuel pressure + fuel filters (including the one under the cab)?

#5 bratlife

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Posted 28 February 2010 - 09:25 PM

yeah I changed both fuel filters right before I put the carb in but I don't have a fuel pressure gauge. no smoke though. as far as the fuel tank vent, I read somewhere that when weberizing an old subaru, and you're taking out all the vacuum lines and valves to make sure that you do not cap the fuel tank vent line. I'm not sure what that means. I know what you're talking about with the vent line back by the tank, but in the post it sounds like they are talking about something under the hood. the problem is that today I drove it and it worked fine all day. I know this sounds good, its just that I'm worried i didn't do something right in the carb swap. if the choke is sticking would it do it more frequently than less than 50% of the time i'm driving it? thanks a lot for your help- I just don't know what to do while its working good. also it feels like there is maybe a little LESS power with the weber than with the old hitachi carb. maybe i should make a different thread for that though. I'm not too sure how it all works on this forum yet.

#6 bheinen74

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Posted 28 February 2010 - 10:29 PM

make sure the choke is closing when the engine is fully cold, and have the air cleaner off looking at it as the engine is warming, the choke flapper should open slowly as it warms up and stay open fully. there is adjustment on it too.

My newly rebuilt weber arrived with the choke coil in BACKWARDs, so as the engine warmed up, it actually was pulling choke on (closed).

otherwise, hard to tell, sure sounds like a choke issue.

#7 bratlife

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Posted 01 March 2010 - 08:02 PM

well its running crappy again today. I drove it yesterday for about 100 miles and ran great. drove it today for a little bit and and it felt good at first then kinda felt like it was skipping and when i came to a stop it almost died and would barely idle. I sprayed around with carb cleaner, even on the mixture screw, and nothing really. the engine was fully warmed up and the choke plates were completely open.
everything else I can think of wouldn't make sense with the fact that it comes and goes without me changing anything. any more ideas would be greatly appreciated.

#8 Dirk

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Posted 01 March 2010 - 10:01 PM

Have a look at your spark plugs. They are the window into your engine. Compare what you see to this:

http://www.theultral.../sparkplugs.htm

Should give you a good idea of whats going on.

The last time I had an intermitent problem like that it was dirt/grit in the jets. Runs fine for a bit, then clogs then unclogs again. No amount of carb cleaner can fix that. If it is this then you have to remove and clean the jets. Not a bad idea to clean out the float bowel while your'e at it.

Check main and idle jets.

Good luck.




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