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the pressure regulator controls the power requirement to the fuel pump
when pressure is reached , it allows power/circuit to the ECM to be broken which in turn stops the pump relay from working
when the pressure drops , that circuit is energized and the ECM switches on the circuit , to the relay allowing power to the pump to supply fuel to get the pressure back up
for the circuit operation you will need a schematics of the electrics for the vehicle ( workshop manual) as some may not use the ECM but go straight from the pressure regulator to the relay through a fuse
You don't say if you have checked that the Fuel Pump is working.
1. You need to check that the fuel pump is operating and getting power.. Have someone turn on the ignition (but not start the engine) If you listen near the FP location you should hear the fuel pump run for 3 seconds and stop. If in doubt do this a couple of times until you can hear the pump run and stop.
2. If you cannot hear the pump running check the fuel system related fuses.
3. If the fuses are good check that the relay for the fuel pump you replaced is functioning. Have someone turn the ignition on and off a few times and listen for the click from the relay or put your finger on it.
4. As a final check have a simple fuel pressure test done on the fuel system if not done already. . If everything is running normally and you are getting good fuel pressure then the starting problem will be somewhere else.
sounds like either the fuel pump relay or the fuel pump itself has gone out. check fuse panel first then check fuel pump relay. if those are good then check power leads to pump at tank and if you have power there then the pump has probably failed. hope this helps. Chris
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.
The truck has a 30Amp fuse link supplying power to the fuel pump relay and the main relay, a 15 Amp fuse then protects the fuel pump circuit. Relay is in the engine compartment fuse box it is Good luck to you. Hope this fixex your problem
Power for the fuel pump is supplied by fuse #16 in the Power Distribution Center (PDC), goes through the Fuel Pump Relay and then to the Fuel Pump and the ground completes the circuit. Power for the Fuel Pump Relay coil is supplied by fuse #18 in the PDC and the Powertrain Control Module (PCM) supplies ground. It is a fairly simple circuit to check.
The first thing to do is check all the fuses, especially #16 and #18. If you have they are good then you will need to pull the fuel pump relay and check for power, with the key ON at the dark green/black wire and orange wire. The DG/BK wire is the power for the fuel pump and the OR wire is the power for the relay coil. If you have power there connect a jumper between the DG/BK wire and the dark green/white wire. You should hear the fuel pump running. If not there is a problem in the DG/WT wire from the relay to the pump.
Okay, lets assume that checks out fine, the next thing to do is replace the fuel pump relay and ground the dark blue wire. You should hear the fuel pump running. Okay? Good, now go to the PCM located on the firewall in the engine room. It has three large connectors, black, white and grey. There is a DB wire in cavity 19of the grey connector. Ground this wire and you should hear the fuel pump running. If it does then the wiring for the fuel pump circuit is all good and the PCM will need to be replaced. If it doesn't run, then you have a problem in the DB wire between the relay and the PCM.
The ECU is usually the last thing a mechanic would suspect for a problem, after eliminating other possibilities. And you should concentrate on what happened to the fuel pressure-why did the fuel pump stop working. So you need to check and test the fuel pump circuit.
Look for the fuel pump fuse first of all and check that it is good. Here is how most fuel pump circuits work: The fuse supplies power to the fuel pump relay (under the hood), and when the relay is activated (or energized) by the ecu signal that goes to the coil side of the relay, then the fused power passes on through the relay and to the fuel pump in the gas tank.
If you have no fuel pressure, the pump has quit working. So to test the circuit, you would use a test light or volt meter at the fuel tank electrical connector. Find the wire for the fuel pump and see if it has power on it when the engine is cranking over. If it does have power, then you need to pull the pump off and replace it. If there is no power to the pump when cranking the engine, the pump circuit must be the problem. Better find a wiring diagram, you will need it to diagnose further.