i got a new/used BAC valve for my 90 gxl, the resistance between terminals is good, but when removed the and adding 12v to it, it clicks but when looking in the back how far back is the plunger go? mine only goes ~1/8"

 

what are you talking about? plunger? BAC?
Any pics?

 

2nd picture shows the "plunger"in side the bck of the BAC solenoid valve.

 

There is no reason to touch that.
If it ohms out and it clicks, install it. There are no other specs for a BAC valve.

I always thought it looked more like a worm gear, but since there's no reason to do anything to it except spray it w/ cleaner every once in a while, I never got around to finding out

 

it won't move back much. I have cut a BAC valve open and observed its operation when energized.

 

thanks

so is it safe to spray some carb cleaner on the "wormgear/plunger" and down the air hose fitting on the other side?

 

I'd use MAF sensor cleaner just to be safe, but its prolly fine.