Possibly OT, ??s about a GM feedback Q-jet

[ae2598 at wayne.edu]

It sounds like this one is a bit of an oddball, there is nothing more than
one 2-wire connector on the carb.  It does sound consistent with what
others are saying about it being a coldstart accelerator pump booster, as
the wiring is in series with a coolant temp. switch!

 On Fri, 9 Mar 2001, Diane Stowe wrote:

> there might be more than one model of 'computerized' quadrajet. The one I am
> speaking of had a 4 pin connector on the top of it.
> 
> The Rochester book goes into excellent detail. I think I just shipped it
> off.
> but you can read it at Barnes and Noble or something. I think if it were all
> intact it would run ok.
> 
> Diane
> ----- Original Message -----
> From: <ae2598 at wayne.edu>
> To: <gmecm at diy-efi.org>
> Sent: Friday, March 09, 2001 7:09 AM
> Subject: Re: Possibly OT, ??s about a GM feedback Q-jet
> 
> 
> > Makes sense, as currently it IS running uncortrollably rich. Apparently
> > the wiring was hacked enough to prevent the ECM from doing its job in the
> > present state.  I have another carb I'll try throwing on there
> > (non-feedback) to see if it performs any better.
> >
> >  On Thu, 8 Mar 2001, Diane Stowe wrote:
> >
> > > as far as the carb goes, it will idle uncontrollably rich without it's
> ecm
> > > controlling the primary metering rods, I think they just pull up if
> there is
> > > no ecm connected.
> > > I had to use one like that without an ecm for a few days.
> > >
> > > when it was all working it wasn't that bad. I just gave away my manuals
> but
> > > I did see good explanations of what was supposed to work etc.
> > >
> > > Diane
> > >
> > > ----- Original Message -----
> > > From: <ae2598 at wayne.edu>
> > > To: <gmecm at diy-efi.org>
> > > Sent: Thursday, March 08, 2001 7:24 PM
> > > Subject: Possibly OT, ??s about a GM feedback Q-jet
> > >
> > >
> > > > I'm kinda at a loss to figure out exactly what I have here, so I'm
> turning
> > > > to you guys for advice.  The vehicle is an '85 K5-Blazer, with a
> > > > computer-controlled (somewhat) Q-jet.  I got it for cheap because the
> gas
> > > > stations that worked on this thing in the past apparently couldn't
> figure
> > > > out what to do with it (other than replace everything underhood!) and
> it
> > > > still runs lousy.
> > > >
> > > > The first thing that I find odd is the HEI distributor.  It has
> advance
> > > > weights and a vacuum can.. In fact, the only way in which it differs
> from
> > > > the "standard" HEI is the use of a 5-pin module, and an extra harness
> > > > hanging out the back.  The pickup coil apparently feeds a signal to
> the
> > > > ECM as well as the module.. probably a timing reference signal.  This
> > > > harness has been butchered by previous repair attempts, and probably
> isn't
> > > > giving much data to the ECM anyway.
> > > >
> > > > The next thing that's not exactly right (IMHO) is the carb itself.  It
> has
> > > > a M/C solenoid, but no TPS or IAC.  Every description I read about the
> C3
> > > > Q-jets shows at least the M/C and TPS, and usually an idle air
> control,
> > > > too.
> > > >
> > > > The ECM seems a bit un-sophisticated.. It is in a very small package,
> and
> > > > has a single connector with only 7 wires connected!  No ALDL that I
> could
> > > > find, and no provisions for a PROM.  The service number is 16042121.
> > > >
> > > > Anyway, what I would like to do is make this a non-computerized motor.
> > > > The distributor seems easy enough, I'll just plug in a 4-terminal
> module
> > > > and all it a day.  As far as the carb, what will be the result of not
> > > > connecting the M/C solenoid?  Are these carbs capable of metering fuel
> > > > without the help of the ECM, or should I just find another Q-jet?
> > > >
> > > > Anyone with ideas to share on this would be appreciated..  the carb
> seems
> > > > to be dumping way too much fuel into the motor at this point, and I'd
> like
> > > > to solve this as cheaply as possible!
> > > >
> > > >
> > >
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