I assume you mean that when a timing light is pointed at the crankshaft pulley, there is no advance past initial base timing. Your 1985 is equipped with the Ford EEC IV electronic control system and utilizes a feedback carburetor and the TFI IV ignition system. I'm sure you have already noted that there is no vacuum advance on the distributor as all timing is controlled by the computer (located behind RF kick panel) based on its observations of the other sensors. Timing that will not advance is generally caused by the computer going into LOS mode. This is the Limited Operating Strategy "fail safe" mode where the computer has encountered an error so great that it can't overcome it, so it operates the whole engine management system on fixed numbers. Generally the computer will go into LOS mode when it loses input from multiple sensors. The computer is able to compensate for the loss of 1 or 2 sensors most of the time. It could also indicate a bad wiring harness, bad TFI module (mounted to distributor), or failing computer.
