I just pulled my coolant temp sensor on my 1990 F150 w/5.8L. Does this sensor monitor air temp or coolant? I ask because I pulled it out and no coolant seems to go through it. Looks like it was always air due to some carbon on it. If it is suppose to be coolant then looks like I have a problem. The wires on the connector are Black/white and all grey. Please help.

 

Where did you remove it from ?

 

I pulled it from the driver side fuel rail. I have since found the correct location and have replaced it. Thanks anyway.

 

Doesn't sound like you pulled the Coolant Temp sensor, the sensor is below the distributor in the intake manifold. The one you pulled sounds like the Air Charge sensor. I think it's called the IAC or something similar. Make sure you have the new coolant sensor wrapped and ready to install, because antifreeze will seep out as soon as you unscrew the old one.