Engine-Codes - Ford - P0191 1999 FORD F150

P0191 1999 FORD F150 Code - Fuel Rail Pressure Sensor Circuit Range/Performance

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3
Table of contents

|P0191 1999 FORD F150 code possible causes

  • Low or no fuel
  • Faulty Fuel Rail Pressure (FRP) Sensor
  • FRP harness is open or shorted
  • FRP circuit poor electrical connection
  • Faulty Fuel Pump

|How is the P0191 1999 FORD F150 code repair?

Start by checking the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.

|P0191 1999 FORD F150 code tech notes

The Comprehensive Component Monitor (CCM) monitors the Fuel Rail Pressure (FRP) pressure for acceptable fuel pressure. The test fails when the fuel pressure falls below or exceeds a minimum/maximum calibrated value for a calibrated period of time.
A FRP PID value during KOER of 138 kpa (20 psi) and 413 kpa (60 psi) for gasoline or 586 kpa (85 psi) and 725 kpa (105 psi) for natural gas vehicles (NG) is acceptable.

|What is the cost to diagnose the P0191 1999 FORD F150 code

Labor: 1.0

The cost to diagnose the P0191 1999 FORD F150 code is 1.0 hour of labor. The auto repair's diagnosis time and labor rates vary by location, vehicle's make and model, and even your engine type. Most auto repair shops charge between $75 and $150 per hour.

|What are P0191 1999 FORD F150 code possible symptoms?

  • Engine Light ON (or Service Engine Soon Warning Light)
  • Engine will not start

|What is P0191 1999 FORD F150 code meaning?

The Fuel Rail Pressure (FRP) Sensor is a diaphragm strain gauge device. The FRP sensor measures the pressure difference between the fuel rail and atmospheric pressure. The FRP sensor nominal output varies between 0.5 and 4.5 volts, with 0.5 volts corresponding to 0 MPa (0 psi) gauge and 4.5 volts corresponding to 26 MPa (3771 psi) gauge. The sensor can read vacuums and may lower the output voltage to slightly below 0.5 volts. This condition is normal and is usually the case after several hours of cold soak before the vehicle dome light is turned on. The FP module is energized at the same time the dome light is commanded on. A disabled or malfunctioning dome light does not affect the FP module control.
The FRP sensor is located on the fuel rail and provides a feedback signal to indicate the fuel rail pressure to the Powertrain Control Module (PCM). The PCM uses the FRP signal to command the correct injector timing and pulse width for correct fuel delivery at all speed and load conditions. The FRP sensor, along with the fuel volume regulator (part of the fuel injection pump), forms a closed loop fuel pressure control system. An electrically faulted FRP sensor results in the deactivation of the fuel injection pump. Fuel pressure to injectors is then provided only by the FP module. When the fuel injection pump is de-energized and the injectors are active, the fuel rail pressure is approximately 70 kPa (10 psi) lower than FP module pressure due to the pressure drop across the fuel injection pump. Thus, if the FP module pressure is 448 kPa (65 psi), then the fuel rail pressure would be approximately 379 kPa (55 psi) if the injectors are active.

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