...having an issue with the stock carb secondary not opening, or should I say not getting fuel.  Does anyone have any info if they're something electronic that controls this, or which component controls this; switch, relay, sensor.  I've replaced the carb 2 with different remanufactered units, all three having the same issue.  I know there's  electrical solenoids and switches.... looking for somewhere to start.  The electronic parts are expensive, so is a carb diaonostic!
Thanks!

Are you sure that its not opening? It needs a reasonable load to get enough vacuum so you aren't likely to see it open while stationary.

...pretty sure its not opening.. you can't feel the power when driving, or hear any difference with the air cleaner off.  I've found a test from Autozone online that tests the idle and WOT "wide open throtle" microswitches.... guess I start there. ....will post results.
Link to test:
http://www.autozone.com/az/cds/en_us/0900823d/80/1e/01/08/0900823d801e0108/repairInfoPages.htm