I have a 92' chev blazer s-10 and the 4x4 isn't engaging. We check the accuator and it's fine. The transfer case is locking in but for whatever reason it's not engaging my front axle. I don't know for sure how the vacuum lines are supposed to go. We have moved them but it's like it's not getting adaquate vacuum pressure. I don't know if it's because it was a fuel injected motor and we changed it to carb and the vacuum lies are just wrong? any ideas?

 

is the front drive shaft spinning?

 

Is the vacuum line to the transfer case switch connected to a full manifold vacuum source (one actually into the intake itself)? Or is it connected to the carb directly? If it is connected to the carb directly, it may not be a proper manifold vacuum source.

Also, the vacuum line must have a check valve and after the check valve a vacuum reservoir to allow for constant vacuum supply to the actuator and HVAC.