[Dcraw]

ive been having troubles with the idle on my sierra, when i turn the headlights on the revs will jump up 500-800 revs so that it sits around 2000 at idle and it some time pulsates up and down. Has anyone had this problem?or any ideas where i can start to fix this?

[want33s]

There is a vacuum operated solenoid valve on the side of the carby.
Check its operation and maybe adjust it.

[coily96]

I couldnt fix mine so i backed the screw off, when it pulsates up and down look for a small arm on the front of the carby, back that screw off.

Mine came good after some driving then i adjusted the screw so revs would sit at 1200 with lights on.