Auto Parts: Harmonic Balancer, crankshaft position sensor, crankshaft sensor

Question
My car use to make a loud noise while I was driving it! I was told to replace my harmonic balancer!  I recently had my harmonic balancer replace for my 1992 Oldsmobile 98 and now my car will not start! I was told in order for my car to start back running i need to purchase a crankshaft sensor! What do i need to do in order to get my car back working?

Answer
    What did you do with the old crankshaft position sensor when the balancer was replaced?  The sensor sits behind the balancer and tells the ECM when to make a spark.  It regulates timing and the spark event itself.  They are a little fragile, a car like yours would normally have already  had its sensor replaced at least once.  However, before you replace the sensor, check to make sure that you don't have spark.  If you do have spark, then the sensor is probably OK.  If it does seem to be OK, then the cam sensor (located on the upper timing gear) is probably bad.  It regulates the firing of the injectors.  Changing the crank sensor is easy, the cam sensor much more involved.