Engine Performance problem
1986 Nissan 200SX 4 cyl Two Wheel Drive Automatic 247000 miles
The guage does not seem to be working properly. The engine seems runs fine, I don't feel any difference, but the guage goes from one extreme to the other showing I have no pressure, to going to the high end, then to the middle. It's not consnstant.
What are the telling signs if I am having problems?