the car doesn't get driven very much. i have put gas treatment in the gas and thought it helped but has caused trouble one time after adding treatment. when the temps are below 60* the car sometimes will not start. the engine turns over but no start. when this happens i can't hear the fuel pump running. after a couple attempts at starting it finally does. i have replace the IAC twice and no help. i have read about testing the fuel pressure when it's not starting, depress the schrader valve on the fuel rail to see if there is pressure present. will try that if it happens again. the fuel pump relay under the hood does click but haven't checked to hear if it's clicking when it won't start. i have wondered if the fuel pressure regulator is sticking. not sure where it's located and can i change it.