P0191 Need to test Fuel pump
#1
P0191 Need to test Fuel pump
2005 5.4L She would have a hard time starting before but after I replaced and fixed everything below she was running really good.
Now back to sputtering, taking a long time to start and now not starting at all.
I have replaced; Fuel Pump, Fuel Filter, FPDM, Plugs and COP's, FRP Sensor, followed the power wire from the FDPM and found it corroded bad so I replaced it, also changed the ground location on the FDPM, I have checked all the wires from the FDPM to the drivers seat, checked all fuses.
I have power to FPDM and I have the diagram for the plug but how can I test (hotwire) the Fuel Pump without lowering the fuel tank? What should be the voltage coming from the FPDM plug? not sure about pin 1 & 6.
How can I test the FRP sensor? what are the specs for voltage?
Now back to sputtering, taking a long time to start and now not starting at all.
I have replaced; Fuel Pump, Fuel Filter, FPDM, Plugs and COP's, FRP Sensor, followed the power wire from the FDPM and found it corroded bad so I replaced it, also changed the ground location on the FDPM, I have checked all the wires from the FDPM to the drivers seat, checked all fuses.
I have power to FPDM and I have the diagram for the plug but how can I test (hotwire) the Fuel Pump without lowering the fuel tank? What should be the voltage coming from the FPDM plug? not sure about pin 1 & 6.
How can I test the FRP sensor? what are the specs for voltage?
#2
@Sandman94F150
The Fuel Pump is not operated by a constant voltage supply. It is operated by pulse modulation (duty cycle 0% to 100%) by the FPDM. My truck (an '04 5.4L) runs around 25 - 40% duty cycle most of the time. I would not hotwire it or apply a 100% duty cycle (direct connection). Heaven only knows how much pressure it might build up.
Likewise, the voltage specs for the FRP sensor is a difficult subject. FRP is vacuum adjusted by a vacuum line running from the FRP sensor down behind the intake manifold on the passenger side. You could have a vacuum leak in that line causing trouble. Far the easiest way to test the fuel pump and/or the FRP sensor would be if you have access to a scanner that can read custom OBDII parameters for Fords IDS (Integrated Diagnostic System). PID # hex 168C is FRP, or Engine Injector Pressure (Fuel Rail Pressure) in PSI. Mine runs around 38 t 40 PSI most of the time.
IDS PID # 1672 hex is Fuel Pump Duty Cycle, in (%)
The Fuel Pump is not operated by a constant voltage supply. It is operated by pulse modulation (duty cycle 0% to 100%) by the FPDM. My truck (an '04 5.4L) runs around 25 - 40% duty cycle most of the time. I would not hotwire it or apply a 100% duty cycle (direct connection). Heaven only knows how much pressure it might build up.
Likewise, the voltage specs for the FRP sensor is a difficult subject. FRP is vacuum adjusted by a vacuum line running from the FRP sensor down behind the intake manifold on the passenger side. You could have a vacuum leak in that line causing trouble. Far the easiest way to test the fuel pump and/or the FRP sensor would be if you have access to a scanner that can read custom OBDII parameters for Fords IDS (Integrated Diagnostic System). PID # hex 168C is FRP, or Engine Injector Pressure (Fuel Rail Pressure) in PSI. Mine runs around 38 t 40 PSI most of the time.
IDS PID # 1672 hex is Fuel Pump Duty Cycle, in (%)
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