While in cruse control at 65 mph on a flat part of I80, the truck slows for no apparent reason, it last for approx 5 secs then she takes off back up to speed.....now at this point no lights, all gauges read great. So when I get to a hill the cruise starts to add fuel for pulling the hill....and she will not speed up, the boost jumps to 24 psi, exh temp goes to 1100, but the truck is slowing down like i just dropped an anchor, pulled off checked for codes, found it, now i went to dealer, got new FCA, installed it, nothing has changed, nows it is Sat nite with no dealers open, anybody help me here.
Thanks, Allen

 

P0251-CP3 PUMP REGULATOR CONTROL

WHEN MONITORED
When the ignition is on.

SET CONDITION
The ECM detects a discrepancy between the PWM supplied to the Electronic Fuel Control Actuator and the PWM returned from the Electronic Fuel Control Actuator.

POSSIBLE CAUSES
Fuel pump
(K181) Fuel control actuator driver open
(K31) Return circuit open from FCA to ECM
(K181) Fuel control actuator driver circuit shorted to external voltage
(K31) Fuel control actuator return circuit shorted to external voltage
(K31) FCA return circuit shorted to (K181) FCA driver circuit
(K181) Fuel control actuator driver circuit shorted to ground
(K181) Fuel control actuator driver circuit shorted to another circuit
(K31) Fuel control actuator return circuit shorted to another circuit
Intermittent condition
ECM
P0148-HIGH PRESSURE COMMON RAIL (HPCR) CHECKSUM

WHEN MONITORED
While the engine is running.

SET CONDITION
A deviation between the fuel pressure set point and the actual fuel pressure.

POSSIBLE CAUSES
Others DTC's present
Fuel leaks
Fuel control actuator
Fuel pressure sensor
Cascade overflow valve
Check valve damaged or blocked
Fuel return lines obstruction, damage, or debris.
Lift pump flow
Air in fuel system
Leaking fuel injectors or high pressure connectors
Pressure limiting valve
High pressure fuel pump
Intermittent condition


I would check this first

Ignition on, engine not running.
Disconnect the Fuel Control Actuator (FCA) harness connector.
Connect an incandescent test light across the Fuel Control Actuator driver circuit and the Fuel Control Actuator return circuit at the fuel control actuator harness connector.
Observe the test light.
The ECM will perform a self test of the circuit which should momentarily flash the test light brightly, one time, approximately 20 seconds after being connected.

NOTE:
Check connectors - Clean/repair as necessary.
Compare test light brightness to that of a direct connection to the battery.
Q: Did the light flash brightly?

YES: Replace the Fuel Pump.

I hope this helps. When is the last time you changed the fuel filter? Do you have a FP gauge? Hope the lift pump isn't going out. I come home tomorrow so if you need some help let me know.

 

Trever,
I change the fuel filter every 8000 to 10000. this one that is in it now has 6100 miles on it....I do not have a FG, Now the CP3 was changed out at approx 274,000. it came with a new FCA, The original lift pump went bad at approx 325,000. It now has the new design in the tank Lift pump. I fill mostly at Flying J and i add 2oz of howes. So i thought i had done all the best babying that i think i can do to keep that $2000 pump really happy,
Here is my cell no. Please call me i cant do nothing until monday.
706-669-2777.
Thanks