Im a little confused as to your setup - is this on your stock IRCM ?? You should be getting 12 volts on both sides of the relay .. almost sounds like excessive resistance in the relay contacts. Have you done a voltage drop test ( test probes wired in parallel between source and output voltage - 12 and 9 volts ) - if youre getting a 3 volt drop on the relay itself, the relay is no good and should be replaced. Or un-plug the fuel pump and see if youre getting 12 volts instead of 9.7.
If the fuel pump has less resistance than the relay ( many aftermarket pumps do ) , that could explain the imbalance between the voltages - Ohms law, Volts / amps / resistance in series .. as the fuel pump warms up during operation, it should increase in resistance and pull more voltage than the relay is using.
- Dan