Fuel Pump Monitor (Without Fuel Pump Driver Module)
The Fuel Pump Monitor (FPM) circuit is spliced into Fuel Pump Power (FP PWR) circuit and is used by PCM
for diagnostic purposes. PCM sources a low current voltage down FPM circuit. With fuel pump off, voltage is
pulled low by path to ground through fuel pump. With fuel pump off and FPM circuit low, PCM can verify
FPM and FP PWR circuits are complete from FPM splice through fuel pump to ground. This also confirms that
FP PWR or FPM circuits are not shorted to power.
With fuel pump on, voltage is supplied from fuel pump relay to FP PWR and FPM circuits. With fuel pump on
and FPM circuit high, PCM can verify FP PWR circuit from fuel pump relay to FPM splice is complete. It can
also verify that fuel pump relay contacts are closed and battery voltage is supplied to fuel pump relay.
Fuel Tank Pressure Sensor
See ENHANCED EVAPORATIVE EMISSION SYSTEM under FUEL EVAPORATIVE SYSTEM under
EVAPORATIVE EMISSION SYSTEMS.
Fuel Rail Pressure Sensor
On Crown Victoria 4.6L NGV, Fuel Rail Pressure (FRP) sensor is a diaphragm strain gauge device in which
resistance changes with pressure. See Fig. 20 . Electrical resistance of a strain gauge increases as pressure
increases, and decreases as pressure decreases. Varying resistance affects voltage drop across sensor terminals
and provides electrical signals to PCM corresponding to pressure. Strain gauge type sensors are considered
passive sensors. A passive sensor is connected to a voltage divider network so that varying resistance of passive
sensor causes a variation in total current flow. Voltage that is dropped across a fixed resistor in series with
sensor resistor determines voltage signal at PCM. This voltage signal is equal to reference voltage minus
voltage drop across fixed resistor.
FPDM
(1)
If a duty cycle meter and breakout box is used, be aware that these values may be reversed
depending on trigger setting of specific meter (for example, 25 percent from FPDM may read as 75
percent on duty cycle meter depending on trigger setting).
(2)
Some scan tools may not have capability to access FP_M PID. Percentage will fluctuate randomly. It
is okay for value to briefly go outside this range, then return.
(3)
Refer to FUEL PUMP under OUTPUT SIGNALS.
2003 Ford Pickup F150
2003 ENGINE PERFORMANCE Theory & Operation - CNG, Flex-Fuel & Gasoline