free wiring diagrams ! Enter vehicle info. year , make , model an engine size . Under system click on engine ,then under subsystem click on fuel controls . Then click the search button , then click blue link .The 7th diagram down shows two fuel pump relays , This I have not seen before ! One is speed cont. relay an the other is just fuel pump relay ? The speed control one has a resistor in the electrical circuit . That is way your droping voltage .
Fuel Pump Electrical Circuit Diagnosis (VIN K)
Fuel Pump Electrical Circuit Diagnosis (VIN 1)
The PCM alters fuel pump speed by energizing the fuel pump speed control relay. Under normal conditions, the fuel pump speed control relay is energized. The applied voltage to the fuel pump is controlled by a resistor assembly. When higher fuel volume is required due to increased engine load, MAP sensor value over 90 kPa the PCM de-energizes the fuel pump speed control relay circuit. The increased voltage to the in-tank fuel pump allows a higher volume of fuel to be delivered to the fuel rail. The PCM also compensates for low system voltage by energizing the fuel pump speed control relay.
Have it check for codes !
Did DTC P0230 or DTC 1260 set?
Go to DTC P0230 Fuel Pump Relay Control Circuit or DTC P1260 Fuel Pump Speed Relay Control Circuit
Go to Step 3