First of all I would like to say hello as I am new to this forum. I am very mechanically inclined but new to the z31 scene. I recently purchased a 1985 z31, turbo, 2 seat. automatic from the original owner. After replacing the gas tank,fuel pump, and sending unit. I finally got running. I did do a timing kit, water pump, cam and crank seal, and finally an alternator swap/upgrade job before trying to crank as it had been sitting for about 10-12 years and no reason to take a chance. It runs good, but still more work to do. Pics will be posted soon.

Now for the reason of my post. There is a blower motor on the left fender well that comes on when I turn the car off and stays on and runs the battery down. Can someone enlighten me as to what its purpose is and how is it controlled by a sending unit or is this a relay issue, the motor works fine I just need to know how to turn it off without just unplugging it. Thanks in advance for any replies.

 

Injector cooling fan. Most people throw them out.

 

It came as standard equipment on the 1985 turbo model.

The fuel injector cooling fan can stay on for 12-15 minutes after you’ve turned the ignition key off. It’s job is to help prevent fuel vapor lock. Coolant temperature determines whether or not the fan should turn on. Now that its summer, it's going to activate more often. The fan can weaken an already weak battery. Some people disconnect or remove the fan. I left mine alone since it's never caused me any problems.