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Re: '87 4kq fuel system problems

At 02:51 PM 7/24/99 -0700, you wrote:
>Symptoms:  black smoke coming out of the tail pipe; excessive fuel
>consumption (below 10 mpg); running extremely rough because spark plugs
>caked with carbon desposits, in some cases clogging the gaps; very black
>Took it to Bellevue Motorsports, they replaced the air hose that runs
>between the ISV and air intake plenum and the O2 sensor, and they reset the
>fuel-air mixture.  I replaced the plugs and the air filter.  The cap and
>rotor are new and the wires < 1 year old.
>Ran better than ever for a couple of days.  I noticed that fuel consumption
>still seems high (hard to guage with no working odometer) and now under
>acceleration the smoke is back.  Also starting to feel a minor hesitation.
>Pulled one of the plugs and it's already black from carbon deposits.
>Any ideas on what is happening to my poor car?
>Aaron Peloquin
>Kirkland, WA

At this point the only thing that will radically effect mixture is the
coolant temp sensor.  This is the white 2 pin sensor mounted on the bottom
of the upper  coolant gooseneck.  the resistance of the sensor is supposed
to be 2.5k ohm at 68 deg F.  Resistance should rise with temp above this in
a very even scale.  I have seen sensor's "drop out" at operating temp so
they will only run poorly when hot,  or the other way around.  Try this and
let us know.

Daniel Jones 84 4ksq x2
Dealer Tech