Rich Running 3.0 CIS Engine. Need Advice
 

81 3.0 CIS engine running rich. All spark plugs are fouled. O2 sensor sooty as well. Lots of smoke for first few seconds when car is started after sitting over night. Car cranks fine but when driven bucks for first few minutes before smoothing out. Plunger in fuel distributor is good and smooth not sticking. Fuel pump just replaced with matched unit for this system. Had car hooked up to exhaust analyzer and the CO is between 1-2%. This system also has the lamba control unit (brain) as well. Any ideas where to start? Thanks.

Just to get a base line, you would do well to aquire a fuel pressure guage and test your pressures. cold, warm and hot.

Also, make sure the timing is correct for your MY.

Aside from that, you could just have some ignition issues where the spark aint makin it, which could cause fouling and a rich condition. You might want to "ohm" out the wires. Some people have also seen sparks flying in a dark garage on SC wires...

1-2% doesnt seem rich to me...isnt that in the normal range?

hopefully, there will be some others to chime in...if it were me, I would start with the pressures and the wires.

a couple of things stick out. it bucks when cold then smooths out.
could be bad fuel pressure/s. they need to be looked at first. along with that, make sure there are no air leaks. you dont want to fix fuel pressure problems and make adjustments then find out you have an air leak and have to do it all over again.

smoke at start up.
could be rich, could be oil leaking past rings or valve guides. also could make plugs black.

1-2% is not rich

now on to other stuff.
what heat range are the spark plugs and how old are they.
is the ignition advance working properly?
is the vacuum advance connected and connected to the correct port
is fuse 18 good?
O2 relay under seat good?
have you checked the duty cycle on the frequency valve? is it working?

Bill, the relay under the seat will give simptoms as though there is a fuel pressure problem. Its inexpensive and you can get it locally.
Bruce