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

[Diane Stowe]

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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