The fan behind the head light only turns on when the key is all the way off.
 

The fan behind the head light only turns on when the key is all the way off. If you put the key in any other position it turns off...I have to unplug it to make it turn off, and i won't turn on at all when the car is on. could it be a reversed wire or something simple hope fully?

Are you talking about the injector cooling fan?

i believe so, the blower fan that is behind the driver side head light, and has the port leading to right above the fan shroud.

Yup thats the injector cooling fan. It's not big deal. I hear a lot of z owners remove them.

Is your motor getting hot (temp gauge going over half way)? I'm sure the Z31 injector fan is programmed in a similar way to the 280zx... if the coolant gets above something like ~220* at any time when the motor is running, once the car is turned off, the injector fan will come on for 17 minutes.

huh that makes sense i need a new radiator the temp stays a little more than half...thanx