How many fuel pump relay fuses is their on a lincoln ls v6

There are no fuel pump "relay" fuses. There is a fuel pump fuse that protects the secondary (contact) side of the fuel pump relay, which supplies power to the Rear Electronic Module (REM), which in turn supplies power via a pulse-width generator to the fuel pump unit. The power for the primary side of the fuel pump relay is supplied by the REM and is protected by the fuse that protects the REM itself. The REM has 3 separate fused inputs and the manufacturer does not provide information to indicate which of these fuses provide the output power from the REM to the fuel pump relay.

If you are trying to diagnose your fuel pump circuits, it is necessary to use a scan tool that has vehicle-specific capabilities and can access fault codes and live data from both the the Powertrain Control Module (PCM) and the REM. Two-way communications and actuator testing is also necessary for certain tests involved in verifying the fuel pump circuits.

The easiest way to verify whether the entire system is working or not would be to check for the proper voltage (over 12.5 volts) at the Fuel Pump Module (FPM) electrical connector. If the correct voltage is present at the FPM connectors, then the fuel pump relay, the REM, and all related fuses are good. However, to do this, once again, it requires a scan tool as described above so that the fuel pump can be commanded ON through the computer system functional tests.