I have 2006 5.4 which has been stalling out and won’t start,I have gotten a code for the fuel rail pressure sensor which I changed and it made no difference it wouldn’t start.The fuel pump won’t stay running I have checked the FP module and tested for a ground and power at the module plug ,and it has both.I have tried jumping the module plug with 2 fuses which will by-pas the module and run the fuel pump at 100% but the pump won’t stay running .I changed the fuel filter and pump and with the new pump.during all of this it would start once in awhile even stayed running for 10 min .I found a rotten wiring harnesses plug under cab removed it and soldered and sealed it. There were 2 wires that had no mates one is a factory dead end and the other is a green and orange !?? Does anyone know were this wire goes.? After fixing the frame wiring the truck ran for a week great ,then the same stalled no start problem.The fuel pressure rail sensor code came up again, and I put in a new one no go. so I went over everything again and the pump won’t stay running .The module plug has power and ground, the fuel pump won’t stay running I have it down to one of the wires that runs from the fp module back to the pump the positive or negative may be broke .Now these two wires run side by side along with a bare ground from module plug to fuel pump all covered in foil .What does this do and can it be rewired? Sorry for the long winded tread and poor English ,any help please

 

the pump does not run continuously... When you turn the key ON, the pump runs for 3 seconds to build up pressure in the fuel rail, then it goes OFF.... When you start the truck the MODULE looks at the PRESSURE and tells the pump to run or shut off.. It cycles on and off to maintain pressure... If you want to run CONTINUOUSLY, you would test with a HOT wire from the battery and a direct ground for the pump..... your pump is 14 years old ? If you have 150K miles or so, it might be time for a new pump anyway.

 

Thanks for the quick reply Stev ,I did replace the fuel pump and was still having these problems.Today we traced the two wires that supply power and ground to the fuel pump from the rear module.
When doing this we dropped the fuel tank and found the electrical plug on the fuel pump loose ,I wiggled it and the truck started(lock clip broken) .When pushing on plug with truck running and watching fuel pressure on scan tool the pressure would drop from 40 to 6 psi ,then stalled and set the code for fuel rail pressure sensor.
Got a used plug end ,soldered it on now it runs great .😀 But now my fuel gauge is not working showing empty, ☹️I took care soldering them.I think I’m getting too old for this.

 

Actually, it's a bit different on this era of systems. The FPDM uses a variable duty cycle control feature to maintain pressure at the desired level at the rail after the engine is running.

Did you verify that the power going TO this bypass remains constant? An issue with the upstream circuitry will also cause the pump to stop running.

Once you verify the INPUT power to the pump is good, then you also need to verify the ground circuit for the pump. That's a grounding stud on the inside of the frame rail back above the rear axle shared with the rear tail lamp assembiles. If you verify that the pump has the correct input power, has a good ground circuit, but still stops running, then it's time for a new pump.