[Zootvsmog]

hello. hoping you blokes can help me out.

1989 sierra 1.3L with the std carby.

when at idle constant blowing of black smoke, rolls coal when you first hit the acc pedal and clears out at higher rpm. choke seems to be working as it should part open at idle and full open on full throttle.
carby has been pulled down in the past and rebuilt, better than it was but not great. idle air mix screw I have wound most of the way in and didn't seem to change much at all. yet to do it with a external rpm gauge.

dose anyone have a vacuum line diagram? my workshop manual has very dark black and white pictures.

could the idle mix solenoid be causing the issue?

what else could I be looking for?

how high are your sierra's revving? mine struggles to get to 5k. foot to the floor im doing 95k's with 29" tyres.

have already replaced
coil
dizzy 10 btdc
spark plugs (black already)
leads
compression is ok

still need to adjust lifters.

thanks in advance.

[fordem]

My thoughts, in no particular order ...

The choke should open completely once the engine reaches operating temperature, so no part open at idle & full open on full throttle.

What idle mix solenoid? I don't think a Sierra carb has an idle mix solenoid, or any idle mix electronics - if I remember correctly the only electrical might be an idle cut solenoid, and possibly the choke. Idle air mix screw? I'm almost certain the idle mix screw adjusts fuel - I don't think I've ever seen a carb that had a mixture screw that controlled air.

Black smoke is a rich mixture, fix the choke, check the float level.