I have a problem were my oil pressure guage doesn't rise when giving it gas. it just stays solid on the first of the three lines to the right. With ignition on, motor off, it stays at the L mark. What could be the problem? Its a 3 wire sensor.

 

Have you attempted checking that power is going through the connector? Is it leaking oil through it? I just took mine out recently as oil was going right through the sender and connector... dripped all over my Y pipe. Now it constantly burns the same old damn oil on the pipe. I replaced my oil pressure sender with a aftermarket oil psi gauge and a copper tubing kit from Equus.