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carb [ex Re: alternator diagnosis]

To: "Peter S." <alfapete@pacbell.net>
Subject: carb [ex Re: alternator diagnosis]
From: Reed Mideke <rmideke@interbase.com>
Date: Fri, 25 Jun 1999 15:16:37 -0700


"Peter S." wrote:
> 
> > You should be able to tell extreme rich from lean by smell,
> > and sooty smoke from the exhaust. Proper mix should barely smell at all.
> > (don't sniff it for too long ;-)
> >
> 
> It smells alright.  Not super bad but noticeable.  Turning the mixture screw
> clockwise (in) does what?
> 
Don't know off the top of my head. I think in is leaner (on DGVs), but
I'm
dylsexic, so it might be out. Somebody on this list must know for sure.
My point though, was that you can turn the screw in one direction,
counting
the turns so you can get back to where you were, until it runs really
bad.
If thats the rich direction, it will smoke and smell bad. If it's the
lean
direction, it will just run bad. Then you turn other way, until it runs
bad
again. If everything else is working right, there should be a nice
smooth zone
in between. I usually turn it to the rich extreme, and then turn it back
a
turn or so past where it starts to run nice. Of course if it doesn't
run smooth in any position, you have to fix that first. 

Hmmm, I noticed that in your original post you say 'idle mixture
adjust',
wheras when I wrote the above I was thinking about main
mixture (on a DGV or SU). Not knowing anything about the ZS carb,
I don't really  know what this means ;-( I know there are
lots of ZS owners out there, so I'll shut up now.

> > If you EGR vacuum diaphragm doesn't hold vacuum, it could be causing
> > a vacuum leak, which will mess up your idle.  If it's old/original,
> > its probably dead. Even if the diaphragm of the vacuum parts is ok,
> > the actual valve is probably clogged with soot. My datsun motor
> > was so clogged that I ran it for a week with the EGR stuff completly
> > removed (and no plate or anything) until it backfired out the
> > carb and blew out the blocks of soot that had been sealing it
> > up. Then it didn't run at all.
> 
> If I operate the valve manually with my fingers its definately flowing
> exhaust.  It just wont hold vacuum.  The plate idea is very tempting.
> Ps
> 
Right. So it's not clogged. If the control doesn't hold vacuum, you
intake
is probably sucking in air. The plate wont help this, but you
could invisbly plug the vacuum line too. If you go the plate route,
try to find a "pass or don't pay" smog check place (they're common
in CA, don't know where you're located), because they might
notice that it's not functioning.


-- 
Reed Mideke                                        rmideke@interbase.com

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