- Fuel pump driver module failure: The fuel pump driver module is responsible for supplying power to the fuel pump. If the driver module fails, it can prevent the fuel pump from receiving the voltage it needs to operate, even if the relay is good.
- Wiring issues: There may be a break or short in the wiring between the relay and the fuel pump, or in between relay and PCM (relay is powered PCM output). This could prevent the voltage from reaching the fuel pump.
- PCM failure: PCM is responsible for activating/deactivating the relay. If the PCM fails or doesn't receive proper input from the fuel pump sensor or other engine sensors, it could cause the relay to not switch on.
- Faulty fuel pump: In rare cases, the fuel pump itself may be faulty, even if it is receiving voltage. If this is the case, replacing the fuel pump will be necessary.
